LIBRARY OF CONGRESS. 



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Shelf ,AjL7-8 

UNITED STATES OF AMERICA. 



CHEMISTRY: 

General, Medical, and Pharmaceutical, 



INCLUDING 



THE CHEMISTRY OF THE U. S. PHARMACOPOEIA. 

A MANUAL 

ON THE GENERAL PRINCIPLES OF THE SCIENCE, AND THEIR 
APPLICATIONS IN MEDICINE AND PHARMACY. 



JOHN ATTFIELD, F.R.S., 

M. A. and Ph.D. of the University of Tubingen ; F. T. 0. ; F. C. S. ; 

Professor of Practical Chemistry to the Pharmaceutical Society of Great Britain; 

Formerly Demonstrator of Chemistry at St. Bartholomew's Hospital, London; 

Honorary Member of Pharmaceutical Societies of Great Britain, St. Petersburg, 

Austria, Denmark, East Flanders, Australasia, and New South Wales; 

Honorary Member of the American Pharmaceutical Association ; 

Honorary Member of the Colleges of Pharmacy of Philadelphia, New York, 

Massachusetts, Chicago, and Ontario, and of the Pharmaceutical Associations of New 

Hampshire, Virginia, Liverpool, Manchester, and the Province of Quebec; 

^Honorary Corresponding Member of the Society of Pharmacy of Paris ; 

One of the Three Editors of the British Pharmacopoeia, 1885; 

Reporter on the British Pharmacopoeia to the Medical Council ; 

Author of a Handbook on Water and Water-Supplies. 



? 



TWELFTH EDITION. 




PHILADELPHIA : 

LEA BROTHERS & CO. 

L889. 



At the First International Pharmaceutical Exhibition, held in 
Vienna in August, 1883, for this MANUAL the Author was 
awarded a Gold Medal. 



Entered according to Act of Congress, in the year 1889, by 

LEA BROTHERS & CO., 

in the Office of the Librarian of Congress, at Washington. All rights reserved. 



& 



Westcott & Thomson, 
Stereotypers and Electrotypers, PhUada. 



COI.T.INS PRINTING HOIISE. 



PREFACE. 



The short title on the back of a book, and even the words 
on the title-page, are generally, and even necessarily, imperfect 
descriptions of the contents, and hence not unfrequently induce 
at the outset misconceptions in the minds of readers. The 
author of Ghemistry : General, Medical, and Pharmaceutical, 
would at once state, therefore, that his chief aim is to teach 
the general truths of chemistry to medical and pharmaceutical 
pupils. So far as laws and principles are concerned, the book 
is a work on General Chemistry ; but, inasmuch as those laws 
and principles are elucidated and illustrated by that large por- 
tion of Chemistry which is directly interesting to medical prac- 
titioners and pharmacists, the book may be said to be a work on 
Medical Chemistry and Pharmaceutical Chemistry. Only in 
this conventional sense would the author speak of Medical and 
Pharmaceutical Chemistry, for the truths of chemistry are 
the same for all students — crystalline verities which cannot be 
expanded or compressed to suit any class of workers. The 
leading principles of the science, however, can as easily be 
illustrated by or deduced from those facts which have interest 
as from those which have little or no special interest to the 
followers of medicine and pharmacy. The grand and simple 
leading truths of chemistry, the lesser truths or principles, and 
nearly all the interesting relationships of elements and com- 
pounds — in a word, the science of chemistry — can be taught to 
medical and pharmaceutical students with little other aid than 
that afforded by the materials which lie in rich abundance all 
around these workers. Such a mode of teaching « the general 
principles of the science, and their applications in medicine and 
pharmacy," is adopted in this volume. It is a mode which 



greatly increases the usefulness of the science to the class 
chiefly addressed, while it in no way diminishes the value of 
chemistry as an instrument of mental culture — an instrument 
which sharpens and expands the powers of observation, which 
enlarges and strengthens memory and imagination, which gives 
point to the perceptive faculties, and which develops and elab- 
orates the powers of thought and of reason. 

This manual is intended, then, as a systematic exponent of 
the general truths of chemistry, but is written mainly for the 
pupils, assistants, and principals engaged in medicine and phar- 
macy. It is essentially a manual of applied chemistry, but it 
is first of all a manual of chemistry. The book will be found 
equally useful as a reading-book for gentlemen having no oppor- 
tunities of attending lectures or performing experiments, or, on 
the other hand, as a text-book for college pupils ; while its com- 
prehensive Index, containing nearly nine thousand references, 
will fit the work for after-consultation in the course of business 
or professional practice. 

From other chemical text-books it differs in three particu- 
lars : first, in the exclusion of matter relating to compounds 
which at present are only of interest to the scientific chemist ; 
secondly, in containing more or less of the chemistry of every 
substance recognized officially or in general practice as a reme- 
dial agent ; thirdly, in the paragraphs being so cast that the 
volume may be used as a guide in studying the science 
experimentally. 

The order of subjects is that which, in the author's opinion, 
best meets the requirements of medical and pharmaceutical 
students in Great Britain, Ireland, America, India, and the 
English colonies. Introductory pages are devoted to a few 
leading properties of the elements. A review of the facts thus 
unfolded affords opportunity for stating the views of philos- 
ophers respecting the manner in which these elements influence 
each other as components of terrestrial matter. The considera- 
tion in detail of the relations of the elementary and compound 
radicals follows, synthetical and analytical bearings being pointed 
out, and attention frequently directed to connecting or underly- 



PREFACE. V 

ing truths or general principles. The chemistry of substances 
met with in vegetables and animals, or similar substances 
artificially produced (the so-called Organic Chemistry), is 
next considered. Practical toxicology, and the chemical as 
well as microscopical characters of morbid urine, urinary 
sediments, and calculi, are then given. The concluding sec- 
tions form a laboratory-guide to the chemical and physical 
study of quantitative analysis. In the Appendix is a long 
table of tests for impurities in medicinal preparations ; also 
a short one of the saturating powers of acids and alkalies, 
designed for use in prescribing and dispensing. 

In the course of the treatment outlined in the preceding 
paragraph it will be observed that the whole of the elements 
are first noticed very shortly, to give the pupil a general view 
of his course of study, and afterward at length and thoroughly ; 
that the chemistry of the common metallic radicals precedes 
that of the rarer, and that the sections on the acidulous radicals 
are similarly divided ; while the basylous radicals are arranged 
according to analytical relations, the common acidulous accord- 
ing to exchangeable value or quantivalence, and rarer acidulous 
radicals alphabetically. By this plan the more important facts 
and "principles are repeatedly brought under consideration, the 
points of view, however, differing according as interest is con- 
centrated on physical, synthetical, analytical, or quantitative 
properties. This arrangement of matter was adopted, also, 
partly from the belief that the separate and general truths of 
Chemistry never enter the mind in the order of any scientific 
classification at present possible. Chemical facts are not yet 
united by any single, consistent theory. In the current state 
of chemical knowledge consistency in the methodical arrange- 
ment even of elements can only be carried out in one direction, 
and is necessarily accompanied by inconsistencies in other direc- 
tions — a result most perplexing to learners, and hence totally 
subversive of the chief advantage of classification. For this 
reason the writer has preferred to lead up to, rather than fol- 
low, scientific classification — has allowed analogies and affinities 
to suggest, rather than be suggested by. classification. Among 



VI PREFACE. 

the acidulous radicals, especially, any known system of clas- 
sification would have given undue prominence to one set of 
relations and undeserved obscurity to others. Then, by sep- 
arating more important from less important matter, instruction 
is adapted to the wants of gentlemen whose opportunities of 
studying chemistry vary greatly, and are unavoidably insuf- 
ficient to enable them to gain a knowledge of the detail or the 
science. One great advantage of the mode of treatment is 
that difficulties of nomenclature, notation, chemical constitu- 
tion, and even those arising from conventionality of language, 
are explained as they arise, instead of being massed under the 
head of " Introductory Chapters," " Preliminary Considera- 
tions," or " General Remarks," which are not unfrequently 
too difficult to be understood by a beginner, too voluminous 
to be remembered except by the aid of subsequent lessons, 
and are consequently the cause of much trouble and con- 
fusion. For an illustration of this treatment the reader is 
referred to the various notes on chemical constitution. (See 
" Constitution of Salts " in the Index.) This plan has also 
admitted of greater prominence being given to " The General 
Principles of Chemical Philosophy," the only section to which 
the student is asked frequently to return until he finds himself 
naturally employing those principles in the interpretation of 
the phenomena obtained by experiment. 

An elementary knowledge of the subjects of Gravitation, 
Heat, Light, Sound, Electricity, and Magnetism cannot be too 
strongly recommended to the student of Chemistry. The first 
portion of this manual would have been devoted to an exposi- 
tion of these branches of physics, so far as they bear on chem- 
istry, did not the many special books on physics render such 
a course unnecessary. Quantitative chemical analysis fre- 
quently involving determinations of temperature, specific 
gravity, and atmospheric pressure, a few paragraphs on these 
subjects are made introductory to the sections on quantita- 
tive operations. 

The theories that matter consists of molecules and that mole- 



PREFACE. Vll 

cules consist of atoms are freely adopted in this book, the 
author believing that in the present state of knowledge and 
education philosophic conceptions regarding chemistry can 
only be taught to medical, pharmaceutical, and the great 
majority of general students by such objective aid. 

The chemical notation of the work is in accordance with 
modern theories. Equations illustrative of pharmacopceial 
processes have a name to each formula. 

In the first edition of this Manual, in 1867, chemical nomen- 
clature was modernized to the extent of defining the alkali- 
metal salts and the earthy compounds as those of potassium, 
sodium, ammonium, barium, calcium, magnesium, and alumin- 
ium, instead of potash, soda, ammonia, baryta, lime, magnesia, 
and alumina. The author confidently believes that this change, 
founded on views now adopted by all prominent writers on 
chemistry, will be accepted and become popular with all the 
followers of medicine and pharmacy. It is a step in the direc- 
tion of simplicity and consistency, and involves far less hypothe- 
sis than is contained in the old system. The name " nitrate of 
potash," for example, w r as based on the pure assumption that 
nitre contained oxide of potassium or potash and nitric anhy- 
dride, then erroneously termed nitric acid. By the modern 
name, "nitrate of potassium," all that is intended to be con- 
veyed is that nitre contains the element common to all potas- 
sium compounds and the group of elements common to all 
nitrates. Under the old method students always experienced 
difficulty in distinguishing salts of the metal from salts of its 
oxide — salts of potassium, for instance, from salts of potash ; 
under the new view no such difficulty arises. Names such as 
potassium nitrate or potassic nitrate are also consistent with 
modern views, but for general adoption are too unlike the orig- 
inal. The contractions in Latin for names like ••nitrate of 
potassium" are identical with the contractions for names 
resembling "nitrate of potash" — an accidental circumstance 
that will much facilitate the general introduction of the for- 
mer among the older medical practitioners and pharmacists, and 
a practical advantage that must determine the choice over 



the other chemically equivalent names just mentioned. The 
author ventures to express some gratification that his use and 
advocacy of this system since 1867 has resulted in its adoption, 
in 1873, in the " Pharmacopoeia of the United States," and, in 
1885, in the " British Pharmacopoeia." Pharmacy among Eng- 
lish-speaking nations will thus sooner or later, in the important 
matter of chemical nomenclature, be in accord with the current 
state of chemical science. 

The Metric System of Weights and Measures (that which, 
doubtless, is destined to supersede all others) is alone used 
in the sections on Quantitative Analysis. In other parts of 
the manual avoirdupois weights and imperial measures are 
employed. 

It is hoped that the numerous etymological references scat- 
tered throughout the following pages will be found useful. 
TTords in Greek have been rendered in English characters, 
letter for letter. The word "official" is used throughout for 
things recognized officially by the compilers of Pharmacopoeias ; 
" officinal" in its original application to the officina or shop. 

Students are strongly recommended to test their progress by 
frequent examination. To this end appropriate questions are 
appended to each subject. 

The author's ideal of a manual of chemistry for medical 
and pharmaceutical students is one in which not only the 
science of chemistry is taught, but in which the chemistry of 
every substance having interest for the followers of medicine 
and pharmacy is noticed at more or less length in proportion to 
its importance, and at least its position in relation to the leading 
principles of chemistry set forth with all attainable exactness. 
The extent to which he has realized this ideal he leaves to 
others to decide. Such a work will doubtless in certain parts 
partake of the character of a dictionary ; but this is by no 
means a fault, especially if a good index be appended ; for the 
points of contact between pure and applied chemistry are thus 
multiplied, and abundant outlets supplied by which a lover of 
the science may pass into other chemical domains by aid of 
other guides, or even into the regions of original research. 



PREFACE. IX 

Among the rarer alkaloids, bitter bodies, glucosides, salts of 
organic radicals, solid fats, fixed oils, volatile oils, resins, oleo- 
resins, gum-resins, balsams, and coloring-matters, mentioned 
in this volume, will be found many such points whence the 
ardent student may start for the obscure or untrodden paths 
of scientific chemistry. 

Within twenty-two years a demand has arisen for twelve 
large editions of this Manual. The First, in 1867, was 
intended as a handbook of practical chemistry only ; but 
the notes and remarks made respecting most of the experi- 
ments were found to be so useful by students that this portion 
of the volume was in the Second Edition (1869) sufficiently 
extended to render the book more fairly complete in itself. 
In response to a call from professional friends in the United 
States in 1870, the work was revised by the author for the 
followers of medicine and pharmacy in America, the chemistry 
of the Preparations and Materia Medica of the United States 
Pharmacopoeia being introduced, and such other adaptations 
included as to form a Third Edition. A Fourth was pre- 
sented to English workers in the autumn of 1872, and, 
founded on the Fourth, a Fifth Edition for American stu- 
dents in 1873. A very large Sixth Edition was published 
in England in 1875, a Seventh in America in 1876, an Eighth 
in 1879, a Ninth in England in 1881, a Tenth in America in 
1883, and an Eleventh in England in 1885. 

The present (Twelfth) edition contains such alterations and 
additions as seemed necessary for the demonstration of the 
latest developments of chemical principles and the latest 
applications of chemistry in pharmacy. The work now 
includes the whole of the chemistry of the United States 
Pharmacopoeia and nearly all the chemistry of the British 
and Indian Pharmacopoeias. 

But the chief new feature is the section on Organic Chem- 
istry, an elaboration of that written for the last British edition 
early in 1885. It has grown out of the section which, in 
previous editions, was termed "The Chemistry of Certain 
Substances of Animal and Vegetable Origin." These sub- 



X PREFACE. 

stances are in the eleventh and twelfth editions of this 
Manual classified according to the system now adopted by 
most authorities, for which followers of chemistry have 
largely to thank the enthusiasm and labors and lucid lit- 
erary work of a former colleague of the author at St. Bar- 
tholomew's Hospital — Professor Auguste Kekule. 

17 Bloomsbury Square, London, } 
February 22, 1889. > 



ADVICE TO STUDENTS 

RESPECTING TPIEIR OBJECT IN STUDYING. 



It is unnecessary to advise you to avoid studying chemis- 
try, or indeed any subject, merely by way of "preparation for 
examination." You will not so mistake the means for the end. 
You are studying to fit yourself for your position in the world. 
Work diligently, study thoughtfully and deliberately — above 
all, be thorough ; otherwise your knowledge will be inaccurate 
and transient, and will be unaccompanied by that enlighten- 
ment of the understanding, that mental training, mental dis- 
cipline, and general elevation of the intellect which constitute, 
in a word, education. When you are thus educated, you will 
with ease and pleasure pass any examination in the knowledge 
you have thus acquired. 

All authorities on education, whether statesmen, teachers, or 
examiners, regard " examination," even by the most highly 
skilled " Board," with ample time at its disposal and a wide 
area from which to select questions, as but a partial test of 
knowledge and an extremely imperfect test of education. It 
is the best, however, that has been devised, and is especially 
useful when, following instead of leading education, it is 
restricted to the subjects of a well-defined, earnestly-followed, 
compulsory curriculum of study — a curriculum defined and 
directed by a competent representative body, wisely admin- 
istered by properly qualified teachers, and earnestly followed 
by pupils possessing sound preliminary training. 

Students! in all honor and in the highest self-interest take 
care that any inefficiencies inseparable from " examination " 
are abundantly compensated by the extent and precision of 
your knowledge and by the soundness and thoroughness of 
your whole education. 



Xll APPARATUS. 

List of Apparatus for Experiments in Analysis. 

List of Apparatus suitable for a three months' course of practical 
chemistry in the summer session of medical schools or for any simi- 
lar series of lessons — including the preparation of elementary gases, 
analytical reactions of common metals and acidulous radicals, anal- 
ysis of single salts, chemical toxicology, and the examination of 
urine, urinary sediments, and calculi : — 

One dozen test-tubes. 

Test-tube stand. 

Test-tube cleaning-brush. 

A few pieces of glass tubing, 8 to 

16 in. long, with a few inches of 

India-rubber tubing to fit. 
Small flask. 
Two small beakers. 
Two small funnels. 
Two watch-glasses. 
Two or three glass rods. 
Wash-bottle. 
Test-paper. 
Filter-paper. 



Small pestle and mortar. 

A 2-pin t earthenware basin. 

A 2-inch and a 3-inch evap. basin. 

Two porcelain crucibles. 

Blowpipe. 

Crucible tongs.. 

Round file. 

Triangular file. 

Small retort-stand. 

Sand-tray. 

Wire triangles. 

Platinum wire and foil. 

Towel. 

Two dozen corks. 

{This set, packed in a deal box, can be obtained of any chemical- 
apparatus maker- for about seven dollars.) 



Apparatus for Experiments in Synthesis and Analysis. 

A larger set, suitable for the performance of most of the synthet- 
ical as well as analytical experiments described in this manual : — 



A set of evaporating-basins, of 
the following sizes : — 

One 8J-ineh. One 4-inch. 

One 7J-inch. Two 3-inch. 

One 6J-inch. 
One retort-stand and three rings. 
Two test-glasses. 
One half-pint flask. 
One half quire of filter-paper. 
Two porcelain crucibles. 
One measure-glass, 5 oz. 
Blowpipe, 8-inch, Black's. 
Two glass funnels. 
One doz. test-tubes (German glass). 
One test-tube brush. 



One pair of 8-inch brass crucible- 
tongs. 
Two soup-plates. 
One flat plate. 
Two spatula-knives. 
One pair of scissors. 
One round file. 
One triangular file. 
One half pound of glass rod. 
One half pound of glass tubing. 
One ft. small India-rubber tubing. 
Three dozen corks of various sizes. 
Platinum wire and foil. 
Test-papers. 
A nest of three beakers. 



{This set, packed in a case, can be obtained of any chemical-ap- 
paratus maker for about twelve dollars.) 

A sponge, towels, and note-book may be included. 



FURNITURE. 



List of Furniture of a Chemical Laboratory. 
The following apparatus should be ready to the hands of students 
following an extended course of practical chemistry in a room set 
apart for the purpose : — 



A bench or table and stool. 
Water-supply and waste-pipe. 
A cupboard attached to a chimney 

with an outward draught. 
A furnace fed with coke ; tongs, 

hot-plate, or sand-bath, etc. 
A waste-box. 
Shelves for chemicals and other 

materials in jars or bottles. 
Gas-supply and lamp with flexible 

tube (or a spirit-lamp and spirit). 



Test-tube rack, two dozen holes. 

Iron stand or cylinder for support- 
ing large dishes. 

Iron adapters for fitting dishes to 
cylinder. 

Pestle and mortar, 5 or 6 inches. 

One 6-inch funnel. 

Brown pan, 1- or 2-gallon. 

White jug, 1-gallon. 

Water-bottle, quart. 

Twenty-eight test-bottles, 6-oz. 



Other articles, such as flasks, retorts, receivers, condensers, large 
evaporating-dishes, may be obtained as wanted. In Quantitative 
Analysis the apparatus described in the sections on that subject will 
be required. 

List of Reagents. 

Certain chemical substances are used so frequently in analytical 
processes that it is desirable to have small quantities placed in bottles 
in front of the operator. As these " reagents " or " test-solutions " are 
generally employed in a state of solution, nearly all the solid salts 
may at once be dissolved (in distilled water). The bottles employed 
should be well stoppered, and of five or six ounces capacity. The 
bottles should not be more than three-quarters full ; single drops, 
if required, can then be poured out with ease and precision. The 
following list of test-solutions is recommended ; directions for 
methods of preparing those not readily purchasable will be found 
by referring to the Index : — 

Sulphuric Acid, strong. 
Nitric Acid, strong. 
Hydrochloric Acid, strong. 
Acetic Acid, strong. 



Sol. of Potash, 5 per cent, or B. P. 

" Soda, 5 to 15 per cent. 

" Amnion., 10 per ct. or B. P. 
Lime-water, saturated. 



The next nine may contain about 10 per cent, of solid salt : — 



Carbonate of Ammonium, with a 
little solution of Ammonia 
added. 

Chloride of Ammonium. 

Phosphate or Arseniate of Am- 
monium. 



Sulphydrate of Ammonium. 
Chloride of Barium. 
Chloride of Calcium. 
Phosphate of Sodium. 
Neutral Chromate. 



The succeeding seven may have a strength of about 5 per cent. : — 

Perchloride of Iron. 
Nitrate of Silver. 
Perchloride of Platinum. 



Ferrocyanidc of Potassium. 
Ferridcyanide of Potassium. 
Iodide of Potassium. 
Oxalate of Ammonium. 



CHEMICAL SUBSTA;NXES. 



List of Solid Chemical Substances for Study. 

List of chemical substances necessary for the practical study of 
the non-metallic elements mentioned on pp. 13 to 31. The quan- 
tities are sufficient for several experiments. 

Chlorate of Potassium . . 1 oz. I Phosphorus J oz. 

Black Oxide of Manganese .1 oz. Hydrochloric Acid . . . . 1 oz. 

Zinc 1 oz. Sulphur i oz. 

Oil of Vitriol 2 oz. I Iodine 1 oz. 

List of chemical substances necessary for the analytical study of 
the metallic and acidulous radicals (pp. 60 to 378). The quantities 
will depend on the frequency with which experiments are repeated 
or analyses performed ; those mentioned are sufficient for one or 
two students. The articles are given in the order in which they 
will be required. The eight substances mentioned in the above 
list are included : — 



The set of test-solutions described 

on the previous page. 

Carbonate of Potassium . 1 oz. 

Tartaric Acid 1 oz. 

Litmus |oz. 

Sulphate of Magnesium . 1 oz. 

Sulphate of Zinc . . . . 1 oz. 

Alum 1 oz. 

Sulphide of Iron . . . . 1 lb. 

Oak-galls 1 oz. 

Sulphocyanate of Potassium \ oz. 

White Arsenic h oz. 

Zinc J lb. 

Charcoal J lb. 

Sulphate of Iron . . . . 1 oz. 

Copper foil 1 oz. 

Sulphate of Copper . . . 1 oz. 

Tartar Emetic ^ oz. 

Mercury 1 oz. 

Corrosive Sublimate . . . J oz. 

Calomel J oz. 



Tin 


. 1 oz 


Bicarbonate of Sodium . 


. 1 oz 


Acetate of Lead . . . 


. 1 oz 


Cyanide of Potassium . 


. \ oz 


Hyposulphite of Sodium 


. 1 oz 


A Lithium Salt . . 


10 grs 


Nitrate of Strontium 


. \ oz 



Black Oxide of Manganese \ lb. 



Chloride of Manganese . \ oz. 

Chloride of Cobalt . . 50 grs. 

Nitrate of Nickel . . . \ oz. 

Chloride of Chromium . . \ oz. 

Gold leaves 2 or 3 

Chloride of Cadmium . . \ oz. 

Nitrate of Bismuth . . . \ oz. 

Bromide of Potassium . . \ oz. 

Starch 1 oz. 

Nitrate of Potassium . . 1 oz. 

Copper borings or turnings 1 oz. 

Indigo \ oz. 

Chlorate of Potassium . . 1 oz u 

Iodine \ oz. 

Spirit of Wine . . . . 1 oz. 

Sulphur 1 oz. 

Acid Oxalate of Potassium 1 oz. 

Citric Acid 1 oz. 

Phosphorus 1 oz. 

Borax 1 oz. 

Turmeric 1 oz. 

Benzoic Acid .... 50 grs. 

| Fluor Spar 1 oz. 

i Tannic Acid .... 50 grs. 

j Gallic Acid 50 grs. 

! Pyrogallic Acid . . . 50 grs. 
I 



The quantities of materials required for the study of Chemistry 
synthetically will necessarily vary with the desires and tastes of 
the operator, or according to the number and requirements of stu- 
dents working together. 



CONTENTS. 



PAGE 

Preface iii 

Advice to Students xi 

Lists of Apparatus xii 

Lists of Furniture of a Chemical Laboratory xiii 

Lists of Reagents xiii 

Lists of Chemical Substances xiv 



GENERAL CHEMISTRY. 

Introduction , 13 

General Properties of the Non-Metallic Elements 15 

Symbols and Derivation of Names of Elements 31 

The General Principles of Chemical Philosophy 36 

Common Metallic Elements, their Official Preparations 
and Tests : — 
Salts of Potassium, Sodium, Ammonium, Barium, Calcium, 
Magnesium, Zinc, Aluminium, Iron, Arsenicum, Antimony, 

Copper, Mercury, Lead, Silver 80 

Analytical Charts for Ordinary Metals 220 

Rarer Metallic Elements, their Official Preparations 
and Tests : — 
Salts of Lithium, Strontium, Manganese, Cobalt, Nickel, 

Chromium, Tin, Gold, Platinum, Cadmium, Bismuth 224 

Analytical Charts for all Metals 255 

Common Acidulous Radicals, Official Acids, and Tests : — 
Chlorides, Bromides, Iodides, Cyanides, Nitrates, Chlorates, 
Acetates, Sulphides, Sulphites, Sulphates, Carbonates, Oxa- 
lates, Tartrates, Citrates, Phosphates, Borates 260 

Salts of Rarer Acidulous Radicals : — 
Benzoates, Cyanates, Formates, Hippurates, Ferrooyariides, 
Ferridcyanides, Fluorides, Hypo-phosphites, Hyposulphites, 



XVI CONTENTS. 

PAGE 

Lactates, Malates, Meconates, Metaphosphates, Nitrites, 
Phosphites, Pyrophosphates, Silicates, Sulphocyanates, 

Tannates, Gallates, Urates, Valerianates 335 

Analytical Chart for Acidulous Radicals 368 

Systematic Analysis 370 

ORGANIC CHEMISTRY. 

Introduction 383 

Alkaloids, Amylaceous and Saccharine Substances, Glu- 
cosides, Alcohol and Allied Bodies, Albumenoid and 
Gelatigenous Substances, Pepsin, Fatty Bodies, Res- 

inoid Substances, Coloring-Matters 500 

Toxicology 545 

Examination of Morbid Urine and Calculi 557 

Official Galenical Preparations 574 

Official Chemical Preparations 576 

Quantitative Analysis : — 

Introductory Remarks 576 

Determination of Atmospheric Pressure 578 

Determination of Temperature 579 

Weights and Measures 585 

Specific Gravity 598 

Correction of the Volume of Gases for Pressure and 

Temperature 604 

Volumetric Analysis 611 

Gravimetric Analysis 639 

Dialysis 685 

Appendix : — 

Table of Official Tests for Impurities in Prepara- 
tions of the United States Pharmacopoeia 689 

Saturation Tables .> 710 

Table of the Proportion by "Weight of Absolute Alco- 
hol in Spirits of different Specific Gravities 711 

The Elements, their Symbols and Atomic Weights 712 

Index T15 



CHEMISTRY: 

GENERAL, MEDICAL, AND PHARMACEUTICAL. 



INTRODUCTION* 



The infinite variety of solid, liquid, and gaseous substances 
of which our earth and atmosphere are composed, may be re- 
solved with more or less difficulty into distinct forms of matter 
appropriately termed Elements, for by no known means can 
they be further decomposed. Some seventy or more elements 
have been proved to exist. A few (such as gold) occur nat- 
urally in the uncombined state, but the greater number are 
combined in so subtle a manner as to conceal them from ordi- 
nary methods of observation. Thus none of the common prop- 
erties of water indicate that it is composed of two elements, 
both gases, but differing much from each other : nor can the 
senses of sight, touch, and taste, or other common means of 
examination, detect in their concealment the three elements of 
which sugar is composed. The art by which these and all other 
compound substances are resolved into their elements is termed - 
Chemistry, a name derived possibly from the Arabic word kamai, 
to eonceal.f The art of chemistry also includes the construction 
of compounds from elements, and the conversion of substances 
of one character into those of another. The general principles 

* Students using; this book as a guide in following chemistry prac- 
tically should read the first three pages, and then commence work by 
preparing oxygen. All students should read the prefatory pages, espe- 
cially the page of "Advice to Students." 

f The idea that common metals contained valuable metals con- 
cealed within them was the one seed from which mainly sprung 
chemical knowledge. The men who endeavored to find the secret 
of such concealment were appropriately termed alchemists, and their 
efforts spoken of as alchemy (at kimia, from ka»uti, to conceal). Their 
persistent labors, generation after generation, were unsuccessful so 
far as the transmutation of baser metals into gold was concerned, yet 
were invaluable to posterity. For new substances were discovered 
and truths of nature unveiled; from these discoveries multiplication 
Of discoveries resulted, and thus grew the still-growing branch o( 
knowledge called Chemistry. 

2 13 



14 THE ELEMENTS. 

or leading truths relating to the elements, to the manner in which 
they severally combine, and to their properties when combined — 
that is, to the properties of the compound substances formed by 
their union — constitute the science of chemistry* 

From these few words concerning the nature of the art and 
science of chemistry, it will be seen that in most of the occu- 
pations that engage the attention of man chemistry plays an 
important part — in few more so than in the practice of Thera- 
peutics"}" and Pharmacy. | 

* Persons who practise the art and science of Chemistry are known 
as Chemists. Some two hundred or more years ago, and before chem- 
istry was a science, the " chemists " were the makers or vendors of 
chemical substances, then only used as medicines. They were the suc- 
cessors of the Alchemists. In Great Britain these chemists and the 
herbalists, otherwise drug-grocers, otherwise druggists, gradually asso- 
ciated to form the " Chemists and Druggists." Between the " Chemist 
and Druggist" and the Physician there existed the Apothecary — the 
putter together of medicines or compounder of physicians' prescrip- 
tions. The Apothecary has since become a medical practitioner, pre- 
scriptions now being " made up " by the Chemist and Druggist. The 
latter in Great Britain, since the year 1868, has the title of Chemist 
and Druggist, his higher title being Pharmaceutical Chemist ; these 
respective designations he legally assumes on passing the Minor and 
Major Examinations conducted by the Pharmaceutical Society of 
Great Britain in accordance with the provis : ons of the Pharmacy Acts 
of 1852 and 1868. The whole class is often spoicen of as that of 
Pharmacists or Pharmaceutists, terms also used in the United States. 
Other classes of chemists are the Analytical Chemists, who give spe- 
cial attention to Analysis: Manufacturing Chemists, who restrict their 
labors to the preparation of chemical substances ; while others devote a 
portion of their knowledge and energies to Chemical Education or to 
Chemical Research, or are appealed to as Consulting Chemists by the 
persons, firms, corporations, or governments needing chemical advice 
respecting industrial processes, hygienic matters, etc. The callings of 
the Consulting and Analytical Chemist are generally united, and the 
professional gentlemen who follow these conjoint avocations also not 
unfrequently occupy professorial or other tutorial positions, sometimes 
adding to these labors more or less work at original chemical research. 
In England, Scotland, and Ireland, nearly all the leading professional 
chemists are Fellows of the Institute of Chemistry of Great Britain and 
Ireland. 

f Therapeutics {Bepa-evrinoc, therapeutikos, from 6epa~evu, therapeuo, 
to nurse, serve, or cure) is that branch of medicine which treats of 
the application of remedies for diseases. The therapeutist also takes 
cognizance of hygiene — that department of medicine which respects the 
preservation of health and of dietetics. 

j Pharmacy (from (pap/uanov, pharmakon, a drug) is the generic name 
for the operations of preparing or compounding medicines, whether 
performed by the Medical Practitioner or by the Chemist and Drug- 
gist. It is also sometimes applied, like the corresponding term, "Sur- 
gery," to the apartment in which the operations are conducted. 



THE ELEMENTS. 15 

Air, water, food, drugs, and chemicals — in short, all material 
substances — are composed, as stated, of elements. An intimate 
knowledge of the properties of these elements, both in the free 
and in the combined st£te, and of the various substances they 
form when they have combined with each other, a knowledge 
of the power or force (the chemical force or chemical affinity) 
by which the elements contained in those compounds are held 
together, and an application of such knowledge to Pharmacy 
and Medicine, must be the objects sought to be attained by the 
learner, for whom especially this book has been written. 



The Elements. — Of the seventy or so known elements about 
forty are of medical or pharmaceutical interest ; of these, about 
two-thirds are metals, and one-third non-metals ; the remainder* 
are so seldom met with in nature as to have received no practical 
application either in medicine, art, or manufacture. Before inti- 
mately studying the elements it is desirable to acquire some gen- 
eral notions concerning them : such a procedure will aLo serve 
to introduce the practical student to his apparatus, and make him 
better acquainted with the various methods of manipulation. f 

Metallic Elements. — With regard to the metallic elements, it 
may be safely assumed that the reader has sufficient knowledge 
for present purposes ; but little, therefore, need now be said 
respecting them. He has an idea of the appearance, relative 
weight, hardness, etc., of such metals as gold, silver, copper, 
lead, tin, zinc, and iron. If he has not a similar knowledge of 
mercury, antimony, arsenium, platinum, nickel, aluminium, mag- 
nesium, potassium, and sodium, he should commence his studies 
by seeing and handling specimens of each of these metals. 

Non-Metallic Elements^ — With regard to the non-metallic 

* A list of the elements will be found at the end of the volume. 

f This allusion to apparatus need not discourage the youngest pupil. 
With the aid of a few phials, wine-glasses, or other similar vessels 
always at hand, he may, by studying the following pages, learn the 
chemical reactions which are constantly occurring in the course of 
making up medicines, understand the process by which medicinal 
preparations are manufactured, and detect adulterations, impurities, 
or faults of manufacture. Among the substances used in medicine 
will be found nearly all the chemical materials required. If, in addi- 
tion, a dozen test-tubes and a few feet of glass tubing be procured, many 
of the experiments described may be performed. For a full list o( 
apparatus and chemical substances see the introductory pages. 

J These bodies are sometimes termed metalloids (from fieraX^ov, mctirf- 
lon, a- metal, and eldog, eidos, likeness) ; but the name is not appropriate, 
for the non-metallic elements have no likeness to metals. 



16 NON-METALLIC ELEMENTS. 

elements, it is here supposed that the student has no general 
knowledge. He should commence his studies therefore by a 
series of operations as follows, on eight of their number. 

OXYGEN. 

Preparation. — As oxygen is the most abundant element in nature, 
forming, though in a combined state, about one-half of the whole 
weight of our globe, it may safely be assumed that this element can 
readily be obtained in the free condition in a state of purity. In 
fact, the air itself contains about one-fifth of its bulk of oxygen, 
though from the air it cannot be separated, at least not easily and 
readily, for experimental purposes. It is preferable to apply heat 
— that force which will often be noticed as antagonistic, so to speak, 
to chemical union ; heat generally separating particles of matter 
further from each other, while chemical attraction tends to bind 
them closer together — it is better to heat certain compounds con- 
taining oxygen 5 the latter is then evolved in its normal, natural 
condition of gas. Several substances, when heated, yield oxygen ; 
but for convenience and economy, the crystalline body known as 
chlorate of potassium is best fitted for the experiment. The size 
and form of the vessel in which to heat it will mainly depend on the 
quantity required ; but for the purposes of the student the best is a 
test-tube, an instrument in constant requisition in studying practical 
chemistry. It is simply a thin tube of glass, a few inches in length, 
and half or three-quarters of an inch in diameter, closed by fusion 
at one end. It is made of thin glass, in order that it may be rapidly 
heated or cooled without risk of fracture. (See Fig. 3 and 4.) 

Outline of the Process. — Heat chlorate of potassium (say, as 
much as will lie on a shilling) in a test-tube, by means of a 
spirit- or gas-flame ; gaseous oxygen is quickly envolved. Be- 
fore applying heat, however, provision should be made for col- 
lecting the gas. (See Fig. 3.) 

Collection of Gases. — Procure a piece of glass tubing about 
the thickness of a quill pen, and a foot or eighteen inches long, 
and fit it to the test-tube by means of a cork in the following 
manner : (Longer tubes may be neatly cut to any size by 
smartly drawing the edge of a triangular file across the glass 
at the required point, then clasping the tube, the scratch being 
between the hands, and pulling the portions asunder, force 
being exerted in a slightly curved direction so as to open out 
the crack which the file has commenced.) The tube is fixed 
in the cork through a round hole made by the aid of a red-hot 
wire, or, better, a rat-tail file, or, best of all, by one of a set of 
cork-borers — pieces of brass tubing sharpened at one end and 
having a flat head at the other. Fit the cork and test-tube to 
each other accurately and closely, but not so tightly as to 
break the test-tube. Setting aside the test-tube for a few 



OXYGEN. 17 

minutes, proceed to bend the long piece of tubing to the most 
convenient shape for collecting the gas. 

To Bend Glass Tubes. — Hold the part of the tube required 
to be bent in any gas- or spirit-flame (a fish-tail gas-jet answers 




Softening and bending Glass Tubes. 

very well), constantly rotating it, so that about an inch of the 

glass becomes heated. It will soon be felt to soften, and will 

then, yielding to the gentle pressure 

of the fingers, assume any required pj~ 2. 

angle. In the present case, the tube 

should be heated at about four inches 

from the extremity to which the cork 

is attached, and bent to an angle of 

about 90 degrees. 

Source of Heat. — The source of heat 
for the test-tube may be the flame of 
an ordinary spirit-lamp, or, still better 
where coal-gas is procurable, a mixture 
of the latter with air. Gas-lamps espe- 
cially constructed to burn a mixture of 
coal-gas and air are sold by chemical- 
apparatus manufacturers. (See Figs. 
3 and 7). 

Collection, etc. (continued). — Fit 
the cork and bent tube into the test- 
tube ; the apparatus will then be 

ready for delivering gas at a convenient distance from the 
heated portion of the arrangement. To collect it, have ready 
three or four test-tubes (or small wide-mouthed bottles) tilled 
with water, and inverted in a basin, or other similar vessel, 
also containing water, taking care to keep the mouths of the 
tubes a little below the surface. Now apply heat to the chlo- 
rate contained in the test-tube, and so arrange the open end of 
the bent tube under the water that the gas which presently 
escapes with effervescence from the melted chlorate may pass 
out from the free end of the tube and may bubble into and 
gradually till the inverted test-tubes. The first tubeful niav be 




18 



NOX-METALLIC ELEMENTS. 



rejected, as it probably consists of little more than the air orig- 
inally in the apparatus, and which has been displaced by the 
oxygen. That which comes afterwards will be pure oxygen. 



Fie. 3. 




liliP! 





i ' j_j 



V 



=T* 



Tins engraving represents the preparation, collection, and storage of small quantities 
of oxygen gas. A test-tube and bent glass tube, joined together by a perforated cork, 
are supported by the aim of an iron stand. (The apparatus might be held by the. 
■ fingers.) The tube is heated by a gas-lamp. (The spirit-lamp shown at the back might 
be used instead.) Gas evolved from the heated substance in the test-tube is displacing 
vater from an inverted test-tube. Spare tubes in a test-tube rack are at hand, and tubes 
already filled are set aside till wanted. A nest of cork-borers, a round file, a triangular 
file, and a test-tube cleaning brush are lying on the table or student's bench. Below are 
cupboards for apparatus, above are bottles containing testing liquids, etc. 



OXYGEN. 19 

As each tube or bottle becomes full, its mouth (still under 
the surface of the water) may be closed by a cork and set 
aside ; or a little cup (such as a porcelain crucible or small 
gallipot) may be brought under the mouth, and the cup, with 
the mouth of the tube in it, be lifted out of the water and 
placed close by till wanted, the water remaining in the cup 
effectually preventing the gas from escaping. 

On the large scale, oxygen may be made in the same way, larger 
vessels (glass flasks or iron bottles) being employed. Less heat also 
will be necessary if the chlorate of potassium be previously mixed 
with very fine sand, or, still better, with about an equal weight of 
common black oxide of manganese. 

Note on the Collection and Storage of Gases. — It may be as well 
to state that nearly all gases, whether for experimental or practical 
purposes, are collected and stored in a similar manner. Even coal- 
gas is generated at gas-works in iron retorts very much the shape of 
test-tubes, only they are as many feet long as a test-tube is inches: 
and the well-known gigantic gas-holders may be viewed as inverted 
iron test-tubes of great diameter. 

Properties. — Free oxygen is a colorless gas. Cailletet and Pictet 
succeeded in liquefying it. Wroblewski and Olszewski have obtained 
it in some amount as a definite, colorless, transparent fluid. Obvi- 
ously, it is not very soluble in water or it could not be collected by 
the aid of that liquid. Oxygen is soluble to a certain extent, however 
(about 2 Yolumes in 100 at common temperatures), or fishes could not 
breathe. Other noticeable features are its want of taste and smell. 

To show the relation of oxygen to combustion, remove one of 
the tubes from the water by placing the thumb over its mouth ; 
apply for a second a lighted wood match to the orifice ; the gas 
will be found to be incombustible. Extinguish the flame of the 
match, and then quickly introduce the still incandescent carbo- 
naceous extremity of the wood half-way down the test-tube ; the 
wood will at once burst into flame, owing to the extreme violence 
with which oxygen gas supports combustion. These tests of the 
presence of free oxygen may also be applied at the extremity of 
the delivery-tube whilst the gas is being evolved. (It is desir- 
able to retain two tubes of the gas for use in subsequent experi- 
ments; also one tube in which only one-third of the water has 
been displaced by oxygen.) 

Relation of Oxygen to Animal and Vegetable Life. — Not only the 
carbon at the end of a piece of charred wood, but any Other sub- 
stance that will burn in air (which, as will be seen presently, is 
diluted oxygen) will burn more brilliantly in pure oxygen. The 
warmth of the body of animals is kept up by the continuous burn- 
ing of tin 1 tissues in the oxygen (of the air) drawn into the system 



20 NON-METALLIC ELEMENTS. 

through the lungs. The product of this combustion is a gaseous 
compound of carbon and oxygen termed carbonic acid gas, a gas 
which, in sunlight, is decomposed in the cells of plants, with fix- 
ation of the carbon and liberation of the oxygen ; hence the atmo- 
sphere is kept constant in composition. 

Memorandum. — At present it is not advisable that the reader should 
trouble himself with the consideration of the chemical action which 
occurs either in the elimination of oxygen from its compounds, or in 
the separation of any of the following non-metallic elements from 
their combinations. It is to the properties of the elements them- 
selves, especially in their free or least active condition, that he should 
at present restrict his attention. Working thus from simple to more 
complex facts, he will in due time find that the comprehension of 
such actions as occur in the preparation of these few elements will 
be easier than if he attempted their full study now. 

HYDROGEN. 

Preparation and Collection. — The element hydrogen is also, 
in the free state, a gas,* and is obtainable from its commonest 
compound, water (of which one-nintb by weight is hydrogen), 
by the agency of hot zinc or iron, but more conveniently by the 
action of either of these metals on cold diluted sulphuric acid. 
The apparatus used for making oxygen may be employed for this 
experiment ; but no lamp is required. Place several pieces of 
thin zincf in the generating-tube (Fig. 4), or in any common 
glass bottle (Fig. 5) or flask, and cover them with water. The 
collecting-tubes (these may be wide-mouthed bottles) being 
ready, add strong sulphuric acid (oil of vitriol) to the zinc and 
water, in the proportion of about one volume of acid to five of 
water, and fit on the delivery-tube, or pour the acid down such 
a funnel-tube | as is shown in Fig. 5; the hydrogen at once 

* Graham obtained alloys of hydrogen with palladium and other 
metals — compounds in which several hundred times its bulk of gas is 
retained by the metal in vacuo or even at a red heat. This was phys- 
ical confirmation of the opinion long held by chemists, that hydrogen 
is a gaseous metal. Graham termed it hydrogenium (other chemists 
hydrium), and considered its relative weight in the solid state to be 
nearly three-fourths that of water. Cailletet and Pictet have since 
actually liquefied and solidified this element. 

t The best form is granulated zinc (Zincum, U. S. P.), made by heating 
scraps of common sheet zinc in an iron ladle over a fire, and imme- 
diately the metal is fnsed pouring it, in a slow stream, into a pail of water 
from a height of 8 or 10 feet. Each drop of zinc thus yields a thin 
little bell, which, for its weight, presents a large surface to the action 
oi' the acid water. If the zinc is allowed to become hotter than neces- 
sary, the little bells will not be formed. A trace of iron in the zinc 
greatly increases the rate at which hydrogen is evolved. 

X Funnel-tubes may be purchased of the apparatus maker, or, if the 



HYDROGEN. 21 

escapes with effervescence from the fluid. Having rejected the 
first portions (or having waited until the air originally in the 
bottle may be considered to be all expelled), collect four or five 
tubes of the gas in the manner described under Oxygen. 
Fig. 4. Fig. 5. 




Preparation of Hydrogen. 

In making larger quantities bottles of appropriate size may be 
employed. Other metals, notably potassium and sodium, liberate 
hydrogen the moment they come into contact with water ; but the 
processes are not economical. 

Properties. — Like oxygen, hydrogen gas is invisible, inodor- 
ous, and tasteless. If made with iron it has a strong smell, 
but this is due to impurities derived from the iron. 

Appty a flame to the mouth of the delivery-tube as soon as 
the operator's judgment tells him that the brisk effervescence 
of hydrogen must have resulted in the driving out of all air 
from the tube, for the mixture of hydrogen and air may explode. 
Ignition of the hydrogen gas ensues, showing that, unlike oxy- 
gen gas, it is combustible. 

Plunge a lighted match well into a tube (or wide-mouthed 
bottle) containing free hydrogen ; the gas is ignited, but the 
match becomes extinguished. This shows that hydrogen is not 
a supporter of combustion. 

Hydrogen gas in burning unites with the oxygen of the air 
and forms water, which may be condensed on a cool glass or 
other surface. Prove this by holding a glass vessel a few 
inches above a hydrogen flame. In burning the hydrogen 
contained in one of the tubes or bottles, the flame is best soon 
when the tube is held mouth upwards, and water poured in so 
as to force out the gas gradually. 

pupil has access to a table blowpipe and (ho nd vantage of a tutor to 
direct his operations, they may be made by himself. 



22 NON-METALLIC ELEMENTS. 

If, instead of this gradual combination of the two elements 
oxygen and hydrogen, they be mixed together in bulk in the 
right proportions and then ignited, they will rapidly combine, 
and explosion will result. Prepare a mixture of this kind by 
filling up with hydrogen a test-tube from which one-third of 
the water has been expelled by oxygen. Remove the tube from 
the water, placing a finger over the mouth, and having a lighted 
match ready, apply the flame ; explosion ensues, owing to the 
instantaneous combination of the whole bulk of the two ele- 
ments and the expansive force of the highly heated steam pro- 
duced. If anything larger than a test-tube is employed in this 
experiment, it should be a soda-water bottle, or some such ves- 
sel equally strong. 

These two gases thus unite at a temperature far higher than that 
of boiling water, two volumes of hydrogen and one of oxygen yield- 
ing two volumes of gaseous water (true steam). 

The noise of such explosions is caused by concussion between the 
suddenly expanded gaseous body and the air. 

The force of the explosion, or, in other words, the force of the 
suddenly heated, and therefore suddenly expanded, steam, is below 
that necessary to break the test-tube. Some force, however, is ex- 
erted, and hence the necessity of the precaution previously suggested 
of allowing all the air which may be in a hydrogen-apparatus to 
escape before proceeding with the experiments. If a flame be ap- 
plied to the delivery-tube before all the air is expelled, the probable 
result will be ignition of the mixture of hydrogen and oxygen (of 
the air) and consequent explosion. But even in this case the gen- 
erating-vessel is not often fractured unless it be large and of thin 
glass, the ordinary effect being that the cork is blown out, and the 
delivery-tube broken on falling to the ground. 

Hydrogen is a prominent constituent of all the substances used 
for producing artificial light, such as tallow, oil, and coal-gas. The 
explosive force of large quantities, such as a roomful of coal-gas and 
air, though vastly below that of an equal weight of gunpowder, is 
well known to be sufficient at least to blow out "that side of* the room 
which offers least resistance. 

The composition of water can be proved analytically as well as 
synthetically, a current of electricity decomposing it into its con- 
stituent gases, twice as much hydrogen as oxygen, by volume, being 
produced. 

Combustion (from comburo, to burn). — The experiments with 
hydrogen and oxygen illustrate the true character of combustion. 
"\\ henever chemical combination is sufficiently intense to be accom- 
panied by heat and light, the materials are said to undergo combus- 
tion. Combustion only occurs at the line of contact of the combin- 
ing bodies : a jet of oxygen will burn in an atmosphere of hydrogen 
quit ! as easily as a jet of hydrogen in oxygen. A jet of air (diluted 
oxygen) will burn as readily in a jar of coal-gas as a jet of coal-gas 
burns in air ; each is combustible, each supports the combustion of 



HYDROGEN. 



23 



the other. Hence the terms combustible and supporter of combustion 
are purely conventional, and only applicable so long as the circum- 
stances under which they are applied remain the same. In the case 
of substances burning in air, the conditions are, practically, always the 
same : hence no confusion arises from regarding air as the great sup- 
porter of combustion, and bodies which burn in it as being combustible. 
Structure of Flame. — A candle-flame or oil-flame is a jet of gas 
intensely heated ; the central portion is unburnt gas ; the next enve- 
lope is formed of partially burnt and very dense, gaseous, and solid 
particles sufficiently highly heated to give light, and the outer cone 
of completely burnt gases. In the figure the sharpness of limit of 
these cones is purposely somewhat exaggerated. Air made, by any 
mechanical contrivance of burner, to mix with the interior of a flame 
at once burns up, or perhaps prevents the formation of dense gases 
giving a hotter, but non-luminous, jet. The air-gas lamps (Fig. 7), 
or "Bunsen" gas-burners commonly used in chemical laboratories 
are constructed on this principle 5 their flame has the additional ad- 
vantage of not yielding a deposition of soot. 



Fig. 6. 



Fig. 7. 




Structure of Flame. 



" Bunsen " or Air-gas Burner. 



In the air-gas lamp, coal-gas escaping from a small orifice draws 
rather more than twice its volume of air (supplied through adjacent 
holes) into its column, and the mixture of gas and air passes upwards 
along a pipe. It only burns at the end, and not within the pipe, 
partly because the metal of the burner, by conducting boat away, 
cools the mixture below the temperature at which it can ignite: 
partly because the velocity with which the mixture flows out is 
greater than the rate at which such a mixture ignites; and partly 
because the proportion of air to gas in this mixture is insufficient 
for perfect combustion, the external air contributing materially to 
the complete combustion of the jet of air-gas. The Davy safety-lamp 
acts on the first-named principle; a wire-gauze cage surrounds an 
oil-flame; an inflammable mixture of gas and air (fire-damp) can 
pass through the gauze and catch lire and burn inside; but the 
lamo cannot ordinarily be communicated to the mixture outside, 



24 NON-METALLIC ELEMENTS. 

because the metal of the gauze and of the other parts cools clown the 
gas below the temperature at which combustion can continue. 

Properties (continued). — Gaseous hydrogen is the lightest sub- 
stance known. It was formerly used for filling balloons, but 
was superseded by coal-gas, because coal-gas, though not lighter, 
is cheaper and more easily obtained. The lightness of hydro- 
gen may be rendered evident by the following experiment : Fill 
two test-tubes with the gas, and hold one with its mouth down- 
wards and the other with its mouth upwards. The hydrogen 
will have escaped from the latter in a few seconds, whereas the 
former will still contain the gas after the lapse of some minutes. 
This may be proved by applying a lighted match to the mouths 
of the respective tubes. 

The illative weight or specific gravity of oxygen is sixteen times that 
of hydrogen. A vessel holding one grain of hydrogen will hold sixteen 
grains of oxygen. The relation of the weight of hydrogen to air is as 
1 to 14.44 or as 0.0693 to 1.0. One grain of hydrogen by weight would 
measure about 27 fluidounces. One grain of hydrogen would, therefore, 
about fill a common wine bottle. Such a bottle would at ordinary tem- 
perature hold about 14-£ grains of air or 16 grains of oxygen. 

Mem. — It is desirable to retain two tubes of hydrogen for use in 
subsequent experiments. 

Diffusion of Gases. — Hy drogen gas cannot be kept in such vessels 
as the inverted test-tubes ; for, though much lighter than air, it dif- 
fuses downwards into the air, while the air, though much heavier, 
diffuses upwards into the hydrogen. This power of diffusion is cha- 
racteristic of all gases, and proceeds according to a fixed law — namely, 
k ' in inverse proportion to the square root of the specific gravity of 
the gas ,: (Graham). Thus hydrogen diffuses four times faster than 
oxygen. This great and important property of diffusion strongly 
suggests that the particles of gases, at least, are always moving, 
never at rest ; how otherwise could gases diffuse into each other, as 
they do, notwithstanding the opposing influence of gravitation? 
Diffusion strongly supports this (Clausius's) Kinetic (aweo, kinto~, I 
move or put in motion) theory of the physical condition of { 



PHOSPHORUS. 

Appearance and Source. — Phosphorus {Phosphorus, TJ. S. P.) is 
a solid element, in appearance and consistence resembling white 
wax : but it gradually becomes yellow by exposure to light. It is 
a characteristic constituent of bones, and may be prepared from bones 
by a process which will be described subsequently. 

Caution. — Phosphorus, on account of its great affinity for oxygon, 
takes fire very readily in the air, and should therefore be kept under 
water. When wanted for use it must be cut under water. It is 
employed in tipping lucifers, though red or amorphous phosphorus 
(vide Index) is least objectionable for this purpose. 

Experiment. — Dry a piece about one-fourth the size of a pea 



NITROGEN. 25 

by quickly and carefully pressing it between the folds of porous 
(filter or blotting) paper ; place it on a plate, and ignite by 
touching it with a piece of warm wire or wood. The product 
of combustion is a dense white suffocating smoke, which must 
be confined at once by placing an inverted tumbler, test-glass, 
or other similar vessel over the phosphorus. The fumes rapidly 
aggregate, and fall in white flakes on the plate. When this 
has taken place, and the phosphorus is no longer burning, 
moisten the powder with a drop or two of water, and observe 
that some of the water is converted into steam, an effect due 
to the intense affinity with which the two combine. 

The powder produced by the combustion of phosphorus is termed 
phosphoric anhydride ; the combination of the latter with the ele- 
ments of water produces a variety of phosphoric aid which dissolves 
in the water, forming on standing a dilute solution of ordinary phos- 
phoric acid. The Diluted Phosphoric Acid of the British and United 
States Pharmacopceias is a similar solution, generally made, how- 
ever, in a different way, and of definite strength. 

NITROGEN. 

Source. — The chief source of this gaseous element is the atmo- 
sphere, nearly four-fifths of which consists of nitrogen (the remain- 
ing fifth being almost entirely oxygen). 

Preparation. — Burn a piece of dried phosphorus, the size of 

a pea, in a confined portion of air. The oxygen gas is thus 

removed, and nitrogen gas alone remains. The readiest mode 

of performing this experiment is to fix a piece of earthenware 

Fig. 8. Fig. 9. 





Preparation of Nitrogen. Decantation of Gases. 

(the lid of a small porcelain crucible answers very well) on a 
thin piece of cork, so that it may float in a dish of water, Place 
the phosphorus on the lid, ignite by a warm rod, and then in- 
vert a tumbler, or any glass vessel of about a half-pint capacity, 
over the burning phosphorus, so that the glass may dip into the 



26 NON-METALLIC ELEMENTS. 

water. Let the arrangement rest for a short time for the fumes 
of phosphoric anhydride to subside and dissolve in the water, 
and then decant the gas into test-tubes in the manner indi- 
cated in Fig. 9, using a tub or other vessel of water of suffi- 
cient depth to permit the glass containing the nitrogen gas to 
be turned on one side without air gaining access. 

Larger quantities of nitrogen gas are made in the same way. Other 
combustibles, as sulphur or a candle, might be used to burn out the 
oxygen gas from the air, but none answers so quickly and completely 
as phosphorus ; added to which, the product of their combustion would 
not always be dissolved by water, but would remain with the nitrogen. 

Mem. — The statement concerning the composition of the air is 
roughly confirmed in isolating nitrogen, about one-fifth of the vol- 
ume of the air originally in the glass vessel having disappeared, its 
place being occupied by water. 

Properties. — Like oxygen and hydrogen, nitrogen gas is 
invisible, tasteless, and inodorous. By pressure Cailletet and 
Pictet condensed it to a liquid. Wroblewski and Obszewski 
have obtained it in some amount as a definite, colorless, trans- 
parent fluid. It is only slightly soluble in water. Free nitro- 
gen is distinguished from all other gases by the absence of any 
characteristic or positive properties. Apply a flame to some 
contained in a tube ; it will be found to be incombustible. Im- 
merse a lighted match in the gas ; the flame is extinguished, 
showing that nitrogen is a non-supporter of combustion. 

The chief office of the free nitrogen in the air is to dilute the 
energetic oxygen, a mere mechanical mixture resulting. 

Nitrogen is fourteen times as heavy as hydrogen. 

The air is nearly fourteen and a half (14.44) times as heavy as 
hydrogen. Its average composition, including minor constituent;, 
which will be referred to subsequently, is as follows : — 

Composition of the Atmosphere. 

In 100 volumes. 

Oxygen 20.61 

Nitrogen 77.95 

Carbonic acid gas .04 

Aqueous vapor 1.40 

Nitric acid ] 

Ammonia > traces. 

Carburetted hydrogen J 

Sulphuretted hydrogen 1 traces in 

Sulphurous acid j towns. 

The above proportions are by volume. By weight there will be 
nearly 23 parts of oxygen to nearly 77 of nitrogen, oxygen being 
the heavier in the ratio of 16 to 14. Ozone (videlndex) is also said 
to be a normal constituent of air. 



CHLORINE. 



27 



Free Nitrogen and Combined Nitrogen. 

The comparative inactivity or negative character of nitrogen in its 
free condition, that is, when uncombined with other elements, con- 
trasts strongly with its apparent influence in a state of combination. 
When its compounds with hydrogen come to be studied, it will be 
found to be, apparently, the chief, or leading, or, in a sense, the 
most important element of those compounds — the ammoniacal com- 
pounds. United with carbon it gives the poisonous cyanic sub- 
stances. With oxygen it gives quite a large group of bodies, 
amongst which are the common and important class of salts termed 
nitrates. With carbon as well as hydrogen and some oxygen it 
affords powerful agents termed alkaloids — near relatives of ammo- 
nia — while the same elements otherwise grouped, with sometimes a 
little sulphur or phosphorus, form the various albumenoid and gel- 
atinoid matters characteristic of the tissues of animals and veg- 
etables. In a perfect structure we should perhaps scarcely regard 
any one element or member as more important than another, still 
such a conclusion almost forces itself upon us as we become ac- 
quainted with the chemical history of combined nitrogen. 

CHLORINE. 

Source. — This element is, in the free state, a gas. Its chief source 
is common salt, more than half of which is chlorine. 

Preparation. — About a quarter of an ounce of salt and the 
same amount of black oxide of manganese are mixed, and 
placed in a test-tube with sufficient water to cover them ; on 
adding a^small quantity of sulphuric acid, the evolution of 
chlorine gas commences. For the mode of collection see the 
following paragraphs. 

Fig. 10. Fig. 11. 




Preparation of Chlorine. 



Another Process. — As the action of the sulphuric acid on the salt 
in the above process is mainly to give hydrochloric acid, the latter 



28 NON-METALLIC ELEMENTS. 

acid (about 4 parts) and the black oxide of manganese (about 1 part) 
may be used in making the gas, instead of salt, sulphuric acid, and 
black oxide of manganese. This, the usual process, is that adopted 
in the British and United States Pharmacopoeias. 

Collection and Properties. — Free chlorine is a suffocating gas. 
Care must consequently be observed in experimenting with this 
element. As soon as its penetrating odor indicates that it is 
escaping from the test-tube, the cork and delivery-tube (sim- 
ilar to that used in making oxygen) should be fitted on, and 
the gas passed to the bottom of another test-tube containing 
water (Fig. 10). When thirty or forty small bubbles have 
passed, their evolution being assisted by slightly heating the 
generating-tube, the latter should be removed to the cupboard 
usually provided in laboratories for performing operations with 
noxious gases, or dismounted, and the contents carefully and 
rapidly washed away. The water in the collecting-tube will 
now be found to smell of the gas, chlorine, being, in fact, solu- 
ble in about half its bulk of water. Chlorine-water is official* 
in the United States Pharmacopoeia {Aqua Chlori, U. S. P.). 

Larger quantities may be made from the hydrochloric acid and 
black oxide of manganese (4 to 1) in a Florence flask, fitted with a 
delivery-tube, the flask being supported over a flame by the ring of 
a retort-stand or any similar mechanical contrivance (Fig. 11). A 
piece of cardboard on the neck of the collecting-bottle, as indicated 
in the figure, retards diffusion of the gas from the bottle during col- 
lection of the gas. 

Mem. — Flasks and similar glass vessels are less liable to fracture 
if protected from the direct action of the flame by being placed oe 
a piece of wire gauze 3 to 4 inches square, or on a sand-bath, that 
is, a saucer-shaped tray of sheet iron, on which a thin layer of sand 
is placed. 



* The Pharmacopoeia and all in it are official (office, Ft., from L. 
officium, an office). There are many things -which in pharmacy are 
officinal (Fr., from L. officina, a shop) but not official. To restrict the 
word officinal to the contents of a pharmacist's shop, and to that por- 
tion of the contents which is Pharmacopceial, is radically wrong, and 
should be avoided. " An official formula is one given under authority. 
An officinal formula is one made in obedience to the customary usage 
of the shop (offizina). To state that any preparation under the sanc- 
tion of the Pharmacopoeia is officinal, is a misapprehension of the 
meaning of the word." — J. Brough. 

That is official which emanates from a recognized authority. Thai 
is officinal which is issued from an officina or workshop. — Joseph Ince. 

Official writings and orders are those issued by official persons. 
Officinal articles are such as are found in a shop. — J. F. Stanford, 
M.A., F.R.S. 



CHLORINE. 29 

The Vapor Chlori, B. P., or Inhalation of Chlorine, is simply 
moist chlorinated lime so placed that some of the chlorine given off 
may be inhaled. 

During these manipulations the operator will have noticed that 
chlorine is of a light-green color. That 'tint is readily observed 
when the gas is collected in large vessels. As it is soluble in water 
(2| vols, in 1 vol. at 60° F.), it cannot be economically stored over 
that liquid. Being, however, nearly twice and a half as heavy as 
air, the gas may be collected by simply allowing the delivery-tube 
to pass to the bottom of the test-tube or dry bottle (Fig. 11). 

The distinctive property of free chlorine is its bleaching 
power. Prepare some colored liquid by placing a few chips 
of logwood or other dyeing material in a test-tube half full 
of hot water. Pour off some of this red decoction into 
another tube and add a few drops of the chlorine-water ; 
the red color is rapidly destroyed. 

Free chlorine readily decomposes offensive effluvia ; it is one of 
the most powerful of the deodorizers. It also decomposes putrid 
and infectious matter ; it is one of the best of disinfectants. (Anti- 
septics are substances which prevent putrefaction. See Index.) 

Combination of Hydrogen with Chlorine, forming Hydro- 
chloric Acid. — If an opportunity occurs of generating the gas 
in a closed chamber or in the open air, a test-tube, of the same 
size as one of those in which hydrogen has been retained from 
a previous operation, is filled with the gas. The hydrogen 
tube is then inverted over that containing the chlorine, the 
mouths being kept together by encircling them with a finger. 
After the gases have mixed, the mouths of the tubes are 
quickly in succession brought near a flame, when explosion 
occurs, and fumes of a compound of hydrochloric acid with 
the moisture of the air are formed. The Hydrochloric Acid 
of Pharmacy (Acidum Hydrochloricvm, U. S. P.) is a solution 
of the gas (made in a more economical way) in water. 

The foregoing experiment affords evidence of the powerful affinity 
of chlorine and hydrogen for each other. Chlorine dissolved in 
water will, in sunlight, slowly remove hydrogen from some of the 
water and liberate oxygen. The bleaching power of chlorine is 
generally referred to this oxidizing effect which it produces in pres- 
ence of water; for dry chlorine does not bleach. 

Density. — Chlorine gas is thirty-five and a half times as heavy as 
hydrogen gas. A wine bottle would hold about 351 grains. 
3* 



30 NON-METALLIC ELEMENTS. 

SULPHUR, CARBON, IODINE. 

The physical properties (color, hardness, weight, etc.) possessed by 
these elements when they are in the free state are familiar. Their 
leading chemical characters in the free state will also be understood 
when a few facts concerning each are made the subject of experiment. 

Sulphur. — Burn a small piece of sulphur ; a penetrating odor 
is produced, due to the formation of a colorless gas, the same 
as that formed on igniting a sulphur-tipped lucifer match. 

This product is a perfectly definite chemical compound of the 
oxygen, from the air, with the sulphur. It is termed sulphurous 
anhydride or sulphurous acid gas. 

Carbon, free, is familiar in the forms of soot, coke, char- 
coal, graphite (or plumbago, popularly termed blacklead), and 
diamond. The presence of combined carbon in wood and in 
other vegetable and animal matter is at once rendered evident 
by heat. Place a little tartaric acid on the end of a knife in a 
flame; the blackening that occurs is due to the separation of 
carbon. The black matter at the extremity of a piece of half- 
burned wood is also free carbon. 

Carbon, like hydrogen, phosphorus, and sulphur, has a great 
affinity for oxygen at high temperatures. A striking evidence of 
that affinity is the evolution of sufficient heat to make the materials 
concerned red or even white hot. When ignited in the dilute oxy- 
gen of the air, carbon simply burns with a moderate glow, as seen 
in an ordinary coke or charcoal fire, but when ignited in pure oxy- 
gen, the intensity of its combination is greatly exalted. The prod- 
uct of the combination of the two elements, if the oxygen be in 
excess, is an invisible gaseous body termed carbonic acid gas ; if 
the carbon be in excess, another invisible gas termed carbonic oxide 
results. 

Iodine. — A prominent chemical characteristic of free iodine 
is its great affinity for metals. Place a piece of iodine, about 
the size of a pea, in a test-tube with, a small quantity of water, 
and add a few iron-filings or small nails. On gently warming 
this mechanical mixture, or even shaking if longer time be 
allowed, the color and odor of the iodine disappear : it has 
chemically combined with the iron : a chemical compound has 
been produced. If the solution be filtered, a clear aqueous 
solution of the compound of the two elements is obtained. 

This compound is an iodide of iron. Its solution, made as above, 
and mixed with sugar, forms, when of a strength of 10 per cent., the 
ordinary Syrup of Iodide of Iron of pharmacy (Syrupus Ferri Iodidi, 
U. S. P.). A strong solution mixed with sugar, glycyrrhiza, gum, 



THE ELEMENTS, THEIR SYMBOLS, ETC. 



31 



etc., constitutes the corresponding Pill (Pilulce Ferri Iodidi, U. S. 
P.). The solid iodide (Ferri Iodidum, B. P.) is obtained on remov- 
ing the water of the above solution by evaporation. 

Sulphur and Iron, also, when very strongly heated, chemically 
combine to form a substance which has none of the properties of a 
mixture of sulphur and iron — that is, has none of the characters of 
sulphur and none of iron, but new properties altogether. The prod- 
uct is termed Sulphide of Iron. Its manufacture and uses will be 
alluded to in treating of the compounds of iron ; it is mentioned 
here as a simple but striking illustration of the difference between a 
chemical compound and a mechanical mixture. 



THE ELEMENTS, THEIR SYMBOLS, Etc. 

From the foregoing statements a general idea will have been ob- 
tained of the nature of several of the more frequently occurring free 
elements. Some additional facts concerning them may be gathered 
from the following Table, which gives the name in full, the symbol 
(or short-hand character)* of the name, and its origin. 

For the purposes of study the elements may be divided into three 
classes — viz., those frequently used in pharmacy, those seldom, and 
those never used. 



Name. 


Symbol. 


Derivation of Name. 


Oxygen .... 





From bgvg (oxus), acid, and yeveaic (gen- 
esis), generation, i. e., generator of acids. It 
was supposed to enter into the composition 
of all acids when first discovered. 


Hydrogen . . . 


H 


From vdcjp (hudor), water, and yeveai.q 
(genesis), generation, in allusion to the 
product of its combination in air. 


Nitrogen .... 


N 


From viTpov (nitron), saidyeveaig (genesis), 
generator of nitre. 


Carbon 


C 


From carbo, coal, which is chieflv carbon. 


Chlorine .... 


CI 


From x^upbg (chloros), green, the color of 
this element. 


Iodine 


I 


From lov (ion), a violet, and euhr (eidos), 
likeness, in reference to the color oi" 1 ti? 
vapor. 


Sulphur .... 


s 


From sal, a salt, and rrvp (pur), fire, in- 
dicating its combustible qualities. Its com- 
mon name, brimstone, has the same meaning, 
being the slightly altered Saxon word brim- 
stone, i. e., burnstone. 


Phosphorus . . . 


P 


<ptie (phos), light, and $£peiv (pherein), to 

bear. The light it emits may be soon on 
exposing it in a dark room. 



* The symbol is also much more than the short-hand character 
will be presently apparent. 



32 



THE ELEMENTS, THEIR SYMBOLS, ETC. 



Potassium 
(Kalium.) 



Sodium . . 
(Natrium.) 



Ammonium . 



Barium 



Calcium . . . . 
Magnesium . . . 



Iron . . . . 
(Ferrum.) 



Aluminium . . 



Zinc 



Arsenium . . . 

Arsenicum or 

arsenic. 

Antimony . . 

(Stibium.) 



Copper . . . 
(Cuprum.) 



Na 



NH 4 



Ba 



Ca 
Mg 



Fe 

Al 

Zn 

As] 
Sb 

Cu 



Derivation of Name. 

Kalium, from kali, Arabic for ashes. Man- 
ufactories in which certain compounds of 
potassium and allied sodium salts are made 
are called alkali-works to this day. Potas- 
sium, from pot-ash; so called because ob- 
tained by evaporating the lixivium of wood- 
ashes in pots. From such ashes the element 
was first obtained, hence the name. 

Natrium, from natron, the old name for 
certain natural deposits of carbonate of 
sodium. Sodium, from soda-ash or sod-ash, 
the residue of the combustion of masses or 
sods of marine plants. These were the 
sources of the metal. 

This body is not an element; but its 
components exist in all ammoniacal salts, 
and apparently play the part of such el- 
ements as potassium and sodium. Sal 
ammoniac (chloride of ammonium) was 
first obtained from near the temple of Ju- 
piter Ammon in Libya; hence the name. 

From ftapvg (bams), heavy, in allusion to 
the high specific gravity of "heavy spar," 
the most common of the barium minerals. 

Calx, lime, the oxide of calcium. 

From Magnesia, the name of the town (in 
Asia Minor) near which the substance now 
called "native carbonate of magnesia" was 
first discovered. 

Prehistoric. — The spelling may be from the 
Saxon iren, the pronunciation probably from 
the kindred Gothic "tarn;" the derivation 
is perhaps Aryan ; it probably originally 
meant metal. 

The metallic basis of alum was at first 
confounded with that of sulphate of iron, 
which was the alum of the Bomans, and 
was so called in allusion to its tonic prop- 
erties, from alo, to nourish. 

From Ger. zinn, tin, with which zinc 
seems at first to have been confounded. 

'ApaeviKov (arsenikon), the Greek name for 
orpiment, a sulphide of arsenium. Common 
white arsenic is an oxide of arsenium. 

2r//3i (stibi), or crl/ipi (stimmi), was the 
Greek name for the native sulphide of an- 
timony. The word antimony is said to be 
derived from avrl (anti, against), and moine, 
French for monk, from the fact that certain 
monks were poisoned by it. 

From Cyprus, the Mediterranean island 
where this metal was first worked. 



THE ELEMENTS, THEIR SYMBOLS, ETC. 



Name. 


Symbol. 


Derivation of Name. 


Lead .... . . 

(Plumbum.) 

Mercury .... 
(Hydrargyrum.) 

Silver 

(Argentum.) 


Pb 

Hg 

Ag 


The Latin word is expressive of " some- 
thing heavy," and the Saxon Iced has a 
similar signification. 

Hydrargyrum, from vScop (hudor), water, 
and apyvpog (arguros), silver, in allusion to 
its liquid and lustrous characters. Mercury, 
after the messenger of the gods, on account 
of its susceptibility of motion. The old 
name quicksilver also indicates its ready 
mobility and argentine appearance. 

"Apyvpoc (arguros), silver, from apybc (ar- 
gos), white. Words resembling the term 
silver occur in several languages, and indi- 
cate a white appearance. 



The following are the names of some of the less frequently 
occurring elements, compounds of which, however, are alluded 
to in the British and U. S. Pharmacopoeias, or met with in 
pharmacy. 



Bromine 
Fluorine 

Boron . 

Silicon . 
Lithium 

Strontium 



Chromium 



Symbol. 



Br 

Fl 



Ce 



Cr 



Derivation of Name. 



From (Hp&fioc (bromos), a stink. It has an 
intolerable odor. 

From fluo, to flow. Fluoride of calcium, 
its source, is commonly used as a flux in 
metallurgic operations. 

From borax, or baurak, the Arabic name 
of borax, the substance from which the el- 
ement was first obtained. 

From silex, Latin for flint, which is nearly 
all silica (an oxide of silicon). 

From Mdeioc (litheios), stony, in allusion 
to its supposed existence in the mineral 
kingdom only. 

This name is commemorative of StrontiaTi, 
a mining village in Argyllshire, Scotland, 
in the neighborhood of which the minora 1 
known as slrontiauite or carbonate of stron- 
tium was first found. 

Discovered in 1803, and named after the 
planet Ceres, which was discovered on Jan. 
1, 1801. The oxalate Of cerium is official, 
but seldom used. 

From YP&l i(l (chroma), color, in allusion to 
the characteristic appearance of its salts. 



34 



THE ELEMENTS, THEIR SYMBOLS, ETC. 



Manganese 



Cobalt 



Nickel 



Tin (Stannum) 



Gold ( Aurum) . 



Platinum . 



Bismuth 



Cadmium . . 



Mn 



Co 



Ni 



Sn 



Au 



Pt 



Bi 



Cd 



Derivation of Name. 

Probably a mere transposition and rep- 
etition of most of the letters of the word 
magnesia, with whose compounds those of 
manganese were confounded till the year 
1740. 

Cobalus or Kobold was the name of a de- 
mon supposed to inhabit the mines of Ger- 
many. The ores of cobalt were formerly 
troublesome to the German miners, and 
hence received the name their metallic 
radical now bears. 

Nickel, from nil, is a popular German 
term for worthless. The mineral now known 
as nickel ore was formerly called by the 
Germans Kupfernickel, false copper, on ac- 
count of its resemblance to copper (Kupfer) 
ore. When a new metallic element was 
found in the ore, the name nickel was re- 
tained. 

Both words are possibly corruptions of 
the old British word staen, or the Saxon 
word stan, a stone. Tin was first discovered 
in Cornwall, and the ore (an oxide) is called 
tinstone to the present day. 

Aurum (Latin), from a Hebrew word sig- 
nifying the color of fire. 

Gold. A similar word is expressive of 
bright yellow in several old languages. 

From platina (Spanish), diminutive of 
plata, silver. It somewhat resembles silver 
in appearance, but is less white and lus- 
trous. 

Slightly altered from the German Wis- 
muth, derived from Wiesematle, "a beautiful 
meadow," a name given to it originally by 
the old miners in allusion to the prettily 
variegated tints presented by the freshly 
exposed surface of this crystalline metal. 

KaSfieia (Kadmeia), was the ancient name 
of calamine (carbonate of zinc), with which 
carbonate of cadmium was long confounded, 
the two often occurring together. 



Gold, Platinum, Tin, and Silicon are classed with the less import- 
ant elements, because their salts are seldom used in pharmacy. 

It will be noticed that the symbol of an element is simply the first 
letter of its Latin name, which is generally the same as in the Eng- 
lish. Where two names begin with the same letter, the less import- 
ant has an additional letter added. 



THE ELEMENTS, THEIR SYMBOLS, ETC. 35 



QUESTIONS AND EXERCISES. 

1. Of how many elements is terrestrial matter composed? 

2. In what state do the elements occur in nature ? 

3. Distinguish between the art and the science of chemistry, 

4. What is the difference between an element and a compound ? 

5. Enumerate the chief non-metallic elements. 

6. Describe a process for the preparation of oxygen. 

7. How are gases usually stored? 

8. Mention the chief properties of oxygen. 

9. What is the source of animal warmth ? 

10. State the proportion of oxygen in air. 

11. Is the proportion constant, and why? 

12. Give a method for the elimination of hydrogen from water. 

13. State the properties of hydrogen. 

14. Why is a mixture of hydrogen and air explosive ? 

15. Explain the effects producible by the ignition of large quan- 
tities of coal-gas and air. 

16. What is the nature of combustion ? 

17. Define a combustible and a supporter of combustion. 

18. Describe the structure of flame. 

19. State the principle of the Davy safety-lamp. 

20. To what extent is hydrogen lighter than oxygen ? 

21. What do you mean by diffusion of gases? 

22. State Graham's law concerning diffusion. 

23. Name the source of phosphorus, and give its characters. 

24. Why does phosphorus burn in air ? 

25. What remains when ignited phosphorus has removed all the 
oxygen -from a confined portion of air? 

26. Mention the properties of nitrogen. 

27. What office is fulfilled by the nitrogen of air ? 

28. State the proportions of the chief constituents of air. 

29. Mention the minor or occasional constituents of air. 

30. What is the proportion by weight of nitrogen to oxygen in 
the atmosphere? 

31. Give the specific gravity of nitrogen. 

32. How is chlorine prepared ? 

33. Enumerate the properties of chlorine. 

34. Define the terms deodorizer and disinfectant. 

35. Explain the bleaching effect of chlorine. 

36. What proportion of hydrogen to chlorine is necessary for the 
formation of hydrochloric acid gas ? 

37. State the prominent physical and chemical characters of 
sulphur. 

38. State the prominent characters of carbon. 

39. State the prominent characters of iodine. 

40. Give the derivations of the names of some of the elements. 

41. What are the symbols of oxygen, hydrogen, nitrogen, carbon. 
chlorine, iodine, sulphur, phosphorus? 



36 GENERAL PRINCIPLES OF 

The Learner is recommended to read the following para- 
graphs on the General Principles of Chemical Philosophy 
carefully once or twice, then to study (experimentally, if 
possible) the succeeding pages, returning to and reading 
over the General Principles from time to time until they 
are thoroughly comprehended. 



THE GENERAL PRINCIPLES OF CHEMICAL 
PHILOSOPHY. 



Definition of Chemical Action. 
The learner may now proceed to study the manner in which sub- 
stances act chemically on each other. By acting chemically it will 
be obvious, from the preceding experiments, that what is meant is 
so affecting each other that the substances are greatly altered in prop- 
erties. A mixture of free oxygen gas and hydrogen gas is still a gas ; 
a chemical compound of oxygen and hydrogen is a liquid — namely, 
water ; here is a great alteration in leading properties. Iodine is only 
slightly soluble in water, and forms a brown-colored solution, and 
iron is insoluble ; but when iodine and iron are chemically combined, 
the product is very soluble in water, forming a light-green solution 
in which the eye can detect neither iodine nor iron, and which is 
utterly unlike iron or iodine in any one of their properties. Sand, 
sugar, and butter rubbed together form a mere mixture, from which 
water would extract the sugar, and ether dissolve out the butter, 
leaving the sand. Tartaric acid, carbonate of sodium, and water 
added to each other, form a chemical compound, containing neither 
tartaric acid nor carbonate of sodium, these bodies having attacked 
each other and formed fresh combinations. These illustrations show 
that chemical action is distinguished from all other actions by (a) 
producing an entire change of properties in the bodies on which it 
is exerted. Chemical action is further distinguished by the fact that 
it (b) only takes place between definite weights and volumes of mat- 
ter. This (a and b) cannot be said of any other action — the action 
of any of the other great forces of nature (gravitation, heat, light, 
electricity, etc.) ; hence the statements (a and b) furnish a sharp and 
precise definition of chemical action or the chemical force, the force 
whose manifestations the reader is studying. Further (c), it is only 
exerted when the substances are close together. 

Atoms. 
In a chemical compound, what has become of the constituents? 
Let the reader place before him specimens of sulphur, iron, and 
sulphide of iron 5 or iodine, iron, solid iodide of iron and its solu- 
tion in water or syrup (Syriqms Ferri Iodidi, U. S. P.). In the sul- 
phide of iron what has become of the sulphur and of the iron from 
which it was made? The mixture of sulphur and iron in combining 
to form sulphide of iron has not lost weight, and. indeed, by certain 
processes it is possible to recover its sulphur as sulphur, and its iron 



CHEMICAL PHILOSOPHY. 37 

as iron ; so that we are compelled to believe, we cannot avoid the 
conclusion, that sulphide of iron contains particles of sulphur and of 
iron. But how small must be those particles ! Rub a minute frag- 
ment to dust in a mortar and place a trace of the powder under the 
highest power of the best microscope ; no yellow particle is visible, 
not the minutest portion of lustrous metal, but dull-brown miniature 
fragments of the original mass. The elementary particles of sul- 
phur and iron, or of the elements in any other compound (the chlo- 
rine and sodium in common salt or the iodine and iron in solution 
of iodide of iron), are, in short, too small to be seen. Can they be 
imagined ? Again, no. The mind cannot conceive of a particle of 
anything (sulphur, iron, sulphide of iron, or what not) so small but 
what the next instant the imagination has divided it. Yet learner 
and teacher must have some common platform on which to reason 
and converse. The difficulty is met by speaking of these inconceiv- 
ably small particles as atoms (arofioc, atomos, invisible ; from the 
privative a and re/uvu), temno, to cut — that which is not cut or divided), 
an expedient suggested by our countryman Dalton at the commence- 
ment of the present century. It is an expedient not perhaps alto- 
gether satisfactory, but is the only one possible to the majority of 
minds in the present state of knowledge and education. We cannot 
speak of iodine and iron uniting lump to lump, as two bricks arc 
cemented together or blocks of wood glued together, for such is not 
the kind of action. We cannot select a minute fragment of each to 
regard as the combining portions, for the minutest fragment we cou d 
obtain is visible, and iodide of iron contains neither visible iodine 
nor visible iron. And yet iodide of iron contains both iodine and 
iron, or, at least, a given weight of the compound is obtained from 
the same weight of the constituents, and the same weight of con- 
stituents is obtainable from an equal weight of the compound. We 
might say that molecules are concerned in the operation, but mole- 
cules means little masses of — of what? there is positively no word 
left with which to carry on conversation and description but atoms. 
Any other mode of treating the matter is too subjective for general 
employment. Moreover, any difficulty in forming a definite concep- 
tion of an atom is met by regarding an atom, not necessarily as 
something which cannot be divided, but as " a particle of matter 
which undergoes no further division in chemical metamorphoses''' 
(Kckule). Even physicists regard atoms from much the same point 
of view; indeed they often speak of still larger portions of matter 
(molecules) as atoms, meaning thereby " something which is not di- 
vided in certain cases that we are considering" (Clifford). 

The Chemical Force. 

What power binds the atoms of a chemical compound together in 
such marvellous closeness of union that in the couple or group they 
lose all individuality? Clearly an attractive force of enormous 
power, a force remotely resembling, perhaps, that which attracts a 
piece of iron to a magnet. Only by such an assumption can we 
conceive that common salt contains chlorine and a metal (sodium). 
or that wood contains carbon, hydrogen, and oxygen. Were not 



38 GENERAL PRINCIPLES OF 

this force thus all-powerful, the carbon in wood would show its 
blackness and other qualities, and the hydrogen and oxygen give 
indications of their gaseous and other characters. This attractive 
force is commonly termed the chemical force, sometimes chemical 
affinity. The word chemism has also been proposed for it, just as 
the magnetic force is termed magnetism, but has not been gene- 
rally adopted. 

Molecules. 

A free, uncombined atom probably cannot exist in a state of iso* 
lation, at common temperatures, for any appreciable length of time. 
For we must regard an atom as the home of an attractive force of 
great intensity, and the moment such an atom is liberated from a 
state of combination (say hydrogen from water, or chlorine from 
salt) — it finds itself in proximity to another atom having similar 
desires for union, so to speak ; the result is an impetuous rushing 
together and formation of either couples, trios, or groups, according 
to. the nature of the atoms. It would be as difficult to conceive of 
separate atoms as to imagine that a strong magnet and a piece of 
steel could be suspended close to each other without being drawn 
together. It is, doubtless, possible to keep some pairs of atoms 
apart by the aid of heat, just as the magnet and steel may be parted 
by a superior amount of force, but such a condition of things is 
probably abnormal. These pairs and other groups of atoms are 
conveniently designated by the one word molecule, the diminutive 
of mole, a mass ; literally little masses. Dissimilar kinds of atoms 
seem to have greater attraction for each other than similar kinds ; 
for, first, the masses of matter met with in nature in the great ma- 
jority of cases contain two or more dissimilar elements ; and, sec- 
ondly, at the moment certain elements are liberated from their com- 
bination, they are very specially active in combining with other, 
different, elements ; that is to say, the chances are not equal that 
the liberated elements will either retain their elementary condition 
or combine to form compounds, but the cases in which compounds 
are formed are actually in great majority. 

Molecules and Atoms. 

The study of the chemistry of molecules, qua molecules, is of 
great interest; but the study of the chemistry of the atoms or 
groups of atoms within molecules is of enormously greater interest. 
A molecule of nitrogen, for instance, is most inactive ; an atom of 
nitrogen has activity which even the most advanced chemist finds 
difficult of realization. 

RECAPIT CLATIOX. 

It is desirable that the learner should here make some experiment 
which will serve to bring again under notice in an applied or con- 
crete form what has just been stated respecting the substances termed 
chemical compounds, and concerning the character of that chemical 
force which resides in the atoms of molecules. The following will 
usefully serve this purpose ; it is the process for detecting a trace of 
sulphurous acid in common liquid hydrochloric acid. 



CHEMICAL PHILOSOPHY. 39 

As already proved, hydrogen gas and chlorine gas, when inter- 
united in a manner presently explained, form hydrochloric acid 
gas : the latter dissolved in water is the ordinary liquid of the ■ 
shops termed Hydrochloric Acid, the Acidum Hydrochloricum or 
Muriaticum of Pharmacopoeias. Commercial samples of this 
liquid not unfrequently contain as an impurity a trace of sul- 
phurous acid gas, a body also already mentioned and experi- 
mentally prepared — a trace too small to be detected by its odor. 
Obtain a specimen of common liquid hydrochloric acid contain- 
ing as an impurity a trace of sulphurous acid, or adopt the more 
simple course of purposely adding a few drops of aqueous solu- 
tion of sulphurous acid (Acidum Sulphurosum* U. S. P.) to 
some hydrochloric acid. (If no sulphurous acid is at hand, 
the object may be accomplished by pouring a quarter or a half 
an ounce of liquid hydrochloric acid into a wide-mouthed bot- 
tle, then burning a fragment of sulphur on a wire or strip of 
wood inside the bottle for a few seconds, and shaking the gas 
and liquid together.) Pour some of the impure liquid hydro- 
chloric acid into a test-tube, add about an equal bulk of water, 
and then drop in some fragments of the metal zinc. Efferves- 
cence will occur, due to the escape of inodorous hydrogen gas, 
together with a small quantity of badly-smelling gas, termed 
sulphuretted hydrogen gas. Bring the mouth of the tube 
under the nose ; the presence of sulphuretted hydrogen will 
at once be recognized. 

The hydrochloric acid has now been tested for sulphurous acid. 
If the experiment be performed on any commercial specimen of the 
acid, and a smell of sulphuretted hydrogen be observed, the ope- 
rator will at once be able to state that the specimen contains sul- 
phurous acid as an impurity. 

Using Dalton's theory of the atomic constitution of matter, the 
explanation of what occurs in the successive steps of the foregoing 
experiment is as follows : — 

Hydrochloric acid is a chemical compound of hydrogen and chlo- 
rine. That it is a chemical compound, and not a mere mechanical 
mixture of hydrogen and chlorine, is shown by the fact that its 
properties are altogether different from the properties of its con- 
stituents. The attractive power or chemical force resident in the 
atoms of chlorine and of hydrogen has caused them to combine in 
the closest manner imaginable and form pairs of atoms or molecules 
of the chemical compound — hydrochloric acid. Zinc being intro- 
duced into the acid, and the atoms of zinc and chlorine having even 
still greater attraction for each other than the hydrogen for the 
chlorine, the zinc and chlorine atoms combine and form a new 

* These aqueous solutions of acids are generally, for the sake o( brev- 
ity, simply termed acids. 



40 GENERAL PRINCIPLES OF 

molecule (termed chloride of zinc) which remains in the liquid, 
while the hydrogen atoms, having the atoms of no other element 
to combine with if the acid is pure, unite to form pairs or mole- 
cules of hydrogen, and in that state escape from the vessel. If the 
acid be impure from the presence of sulphurous acid (sulphurous 
acid gas, it will be remembered, is a compound of sulphur and 
oxygen), some of the hydrogen atoms, at the moment of their birth, 
their nascent state (from nascor, to be born) — the specially active 
state — finding the atoms of other elements present, namely, the 
atoms of sulphur and oxygen of the sulphurous acid molecules, 
combine by preference with these atoms and form new molecules, 
the sulphur and hydrogen forming sulphuretted hydrogen, and the 
oxygen and hydrogen producing water : the former escapes with 
the great bulk of the hydrogen, while the water remains with the 
water already in the vessels. 

Note. — Ordinary hydrogen gas, that is, hydrogen in the molecular, 
not in the atomic or nascent condition, will not thus attack sulphur- 
ous acid. Doubtless the amount or extent of attraction of two 
atoms of hydrogen for one atom of, say, the sulphur in the sulphur- 
ous acid molecule is a constant amount but the uncombined nas- 
cent atoms can, it is only fair to suppose, get much nearer to the 
attacked molecule than they can after they have themselves com- 
bined to form a molecule, molecules (but scarcely atoms) having 
an appreciable amount of space between them, as will be further 
shown almost immediately. In other words, it is probably distance 
which prevents an attack which would be inevitable at close quar- 
ters. These remarks apply to all similar reactions of other elements. 
The activity of nitrogen in what the student will now see is its atom- 
ic rather than merely nascent condition, as compared with its inac- 
tivity in what now may be termed its molecular condition, has already 
been alluded to (page 27). 

Conditions and Nature of the Manifestation of the Chem- 
ical Force. 

The exertion of chemical affinity is only possible when the masses 
of the bodies touch. Thus it was necessary to bring the oxygen, 
hydrogen, phosphorus, chlorine, sulphur, carbon, iodine, and iron 
into ordinary contact, in the respective experiments with those ele- 
ments, before the various reactions occurred. The exact nature of 
these actions, as indeed of all in which substances act chemically, 
would seem to be an interchange, most generally a mutual one, of 
the atoms of which the molecules consist — a change of partners, so 
to speak. Thus, in the experiment in which hydrogen and chlorine 
gases united to form hydrochloric acid gas, a pair of atoms in a hy- 
drogen molecule, and a pair of atoms in a chlorine molecule, find- 
ing themselves opposite to each other, change places, the atoms of 
each of the old molecules unlinking, so to say, and pairing off in 
fresh couples — as two brothers who for many years have been close 
companions, and two sisters similarly united, thrown freshly into 
each other's society, soon accept new and still more congenial cou- 
plement. 



CHEMICAL PHILOSOPHY. 41 

f Hydrogen \ , j Chlorine 1 WoTTlfl f Hydrogen ) , f Hydrogen "I 
\ Hydrogen J and \ Chlorine J become \ Chlorine J ana \ Chlorine / 

Or, using the symbols of these elements instead of the full names, 

H H and CI CI become H CI and H CI. 

Still further economizing space and trouble, the same statement 
may be made in the following form : — 

H 2 and Cl 2 become 2HC1. 

Once more, by using the plus (+) instead of the words "and" or 
"added to," and the sign or symbol = or equal instead of the words 
"become" or "are equal to," we reach the shortest method of ex- 
pressing this chemical action : — 

H 2 + C1 2 = 2HC1. 

This is the form in which such an action may be expressed in the 
student's note-book. It is the shortest and most convenient form, 
and is instructive and suggestive to the mind. 

Chemical Notation. 

We have thus gradually arrived at a spot in the path of chemical 
philosophy at which we must halt to more fully discuss the usual 
method of recording chemical travels. We have arrived at the sub- 
ject of chemical notation (from noto, I mark), the art or practice of 
recording chemical facts by short marks, letters, numbers, or other 
signs. Already the first capital letter, or the first and one of the 
following small letters of the Latin names of the elements have been 
employed as contractions, or short-hand expressions, or symbols of 
the whole name. Thus H has been used for the word " hydrogen," 
and CI for " chlorine." A second function of such a symbol is that 
of indicating one atom. Thus H stands not only for the word or 
substance " hydrogen," but for one atom of hydrogen. Large and 
small figures (2 or 2 ) indicate a corresponding number of atoms, the 
small figure only multiplying the one particular symbol to which it 
is attached, while a larger figure multiplies all the symbols it pre- 
cedes. Thus H 2 means two atoms of hydrogen, and Cl 2 two atoms 
of chlorine 5 while 2IIC1 means two atoms of hydrogen and two 
atoms of chlorine, or, in one word, two molecules of hydrochloric 
acid gas. A third function of such a symbol as H or CI is that of 
indicating one volume of the element in the gaseous state. Thus II, 
CI, and stand, first, for the substances named hydrogen, chlorine, 
and oxygen ; secondly, for single atoms of hydrogen, chlorine, and 
oxygen. Thirdly, they represent single and equal volumes of chlo- 
rine, hydrogen, and oxygen. It will be remembered that one test- 
tubefnl of hydrogen and an equal sized test-tubeful of chlorine were 
employed in a previous experiment in forming hydrochloric acid 
gas, HOI. 

The position of symbols counts for something. Thus 1IC1 indi- 
cates not only the substances hydrogen and chlorine, single atoms 
of each of the substances, and equal volumes of each, but also that 



42 GENERAL PRINCIPLES OF 

the two substances are joined together by the chemical force. If the 
two letters were placed one under the other, or at some distance 
apart, or were separated by a comma or a plus sign (+), they would 
be understood to mean a mere mixture of the elements ; but placed 
as close as the printer's types will conveniently and consistently 
allow, they must be considered to stand for a compound of the ele- 
ments, that is to say, hydrochloric acid gas (HC1). The collection 
of symbols representing a molecule is termed a formula. H 2 , Cl 2 , 
and HC1 are the formula? of hydrogen, chlorine, and hydrochloric 
acid gas. 

H 2 + C1 2 = 2HC1. 

Such a set of letters, figures, and marks as that on the preceding line 
is collectively termed an equation, because it indicates the equality 
of the number and nature of the atoms before and after chemical 
action. On the left hand of the sign of equality are shown two 
molecules, and on the right hand two molecules ; but, of the mole- 
cules on the left, one contains two atoms of hydrogen and the other 
two atoms of chlorine, while of the molecules on the right each con- 
tains one atom of hydrogen and one of chlorine. The equation forms 
a short and convenient plan of recording the facts of experiment. 

Instead of an equation, a diagram may be employed to exhibit 
the same fact. Thus : — ■ 

HC1 




HC1 

PHYSICAL AND CHEMICAL CONSTITUTION OF 
MATTER. 

Relations of Gases, Liquids, and Solids. 

Molecules of gases are not in absolute contact, for a volume of 
gas may be compressed Avith very little force to half or one-fourth 
its bulk — in short, to such an extent that in many cases the mole- 
cules sufficiently approximate to form a liquid. In a liquid the 
molecules are still free to glide about with ease amongst each other ; 
and though in solids they exhibit less mobility, still even solids 
may be compressed by powerful pressure, so that probably in no 
instance are molecules in absolute contact. (Moreover, from the 
researches of Caignard de la Tour and of Andrews there would 
seem to be no sharp lines of demarcation between the gaseous, 
liquid, and solid conditions of substances.) One's mental picture 
of the relative position of the molecules of gaseous, vaporous, 
liquid, or solid matter must be such a picture as that of the mov- 
ing particles of dust in the air of a room, or such a relation to each 
other as that of the planets and stars suspended in space. There is 
abundant experimental evidence to warrant Such a conception. A 



CHEMICAL PHILOSOPHY, 



43 



clear transparent fluid appears perfectly homogeneous, but is not so. 
Its particles are not in contact. Every one who has mixed 5 pints 
of rectified spirit with 3 pints of water knows that the 100 fluid- 
ounces of spirit and 60 fluidounces of water do not when mixed 
give 160 ounces of " proof" spirit, but only 156 ounces ; the mole- 
cules of the liquids have gone closer together, having probably a 
little attraction for each other. Why a gas under pressure should 
immediately return to its original bulk when the pressure is re- 
moved, while a liquefied or solidified gas only slowly resumes the 
gaseous or vaporous state, is a question which requires for discus- 
sion a knowledge of the nature of forces other than the chemical. 
For it must be remembered that the study of the chemical force is 
mainly the study of the internal constitution of molecules, the study 
of the properties of entire molecules forming the domain of Physics 
— sometimes termed Natural Philosophy. (Physics, from <pvmc, 
phusis, nature, that is, visible and material nature 5 the study of 
actions and reactions which do not involve entire and permanent 
change in the properties of bodies — the study of the action of heat, 
light, electricity, magnetism, gravitation, etc., on matter.) 

It is necessary, however, to state something more about the 
physical as well as the chemical conditions of the molecules of a 
gas in order that the. learner may be prepared for the fact, that mix- 
tures of certain gaseous elements, in combining to form gaseous 
compounds, diminish considerably in volume. Thus, while a pint 
of hydrogen and a pint of chlorine give a quart of hydrochloric 
acid gas, 



Hydrogen. 


Chlorine. 



Hydrochloric acid gas. 



two pints of hydrogen and one of oxygen are necessary to produce 
a quart of gaseous water (steam). It will be remembered that two 
volumes of hydrogen and one of oxygen were necessary in a pre- 
vious experiment in which water was formed. 



Hydrogen. 


Hydrogen. 


Oxygen. 



Gaseous water (steam). 



Now, that a pint of hydrogen gas and a pint of chlorine gas should, 
after chemical reaction or rearrangement of the atoms 01 the mole- 
cules lias taken place, form two pints of hydrochloric acid gas. is 
quite what we should expect. For, first, the reader, by this time, 
is not astonished that the chemical combination is attended 1>\ entire 



4\ 



GENERAL PRINCIPLES OF 



change of properties : and, secondly, the experience of years has 
led him to expect that a pint of one thing added to a pint of another 
gives two pints of the mixture. But that two pints of hydrogen and 
one pint of oxygen should, after combination (and under like con- 
ditions of temperature and pressure), give, not three, but two pints 
of product (steam) is perhaps somewhat astonishing, and needs 
explanation. To this end let us picture a few of the molecules 
of hydrogen and as many molecules of chlorine. Draw with a 
pencil on paper several pairs of crosses ( -f- + ) to represent hydro- 
gen molecules, and circles (O O) for chlorine molecules, or, if colored 
ink is at hand, red pairs of dots for hydrogen and green for chlo- 
rine. Or, at once, for facility in printing, let the following pairs of 
letters h h represent a few (say, nine) molecules of hydrogen, and 
c c molecules (nine) of chlorine — before combination. 



hh 


hh 


hh 


c c 


c c 


c c 


hh 


hh 


hh 


c c 


c c 


c c 


hh 


hh 


hh 


c c 


c c 


c c 



Then, after combination, we shall have eighteen molecules of 
hydrochloric acid gas : — 



h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 



But when two volumes of hydrogen and one of oxygen combine 
and give two volumes of steam, the mental picture must be not that 
of molecules somewhat nearer to each other than before, nor any 
difference in the size of the molecules, but a picture of molecules 
containing three instead of two atoms — thus, still using pairs of 
letters, just for the moment, to represent a few (the space will allow 
only twenty-seven) molecules : — 



hh 


hh 


hh 


hh 


hh 


hh 











hh 


hh 


hh 


hh 


hh 


hh 


O 








hh 


h.h 


hh 


hh 


hh 


hh 












The twenty-seven molecules (eighteen hydrogen, nine oxygen) 
will, after combination, become eighteen molecules of steam : 



h o h h oh h oh 
h oh h o h ho h 
h o h h o h h o h 


h oh h oh h oh 
h o h h o h h o h 
h o h h o h h o h 



As already suggested, one's mental picture of a number of mole- 
cules may well give them such a relation to each other as that of a 
number of solar systems in the universe, equally distant from each 
other and each occupying a similar space, yet one system containing 
a sun and one planet, another a sun and two planets, and so on, or 
even one or more of the planets having one or more moons. Indeed 



CHEMICAL PHILOSOPHY. 45 

the atoms in some very complex molecules really appear to have 
very much the relation to each other of the sun, planets, and moons 
of a solar system. To indicate such molecules by letters as above 
would, of course, require more space than is there given to the 
assumed pictures of molecules. 

Here occurs an opportunity that must not be lost of stating a 
mode of reasoning by which a molecule of oxygen (or of many other 
elements) is shown to be a double structure — shown to contain two 
atoms. Five equal-sized bottles are before us, two filled with hydro- 
gen, one with oxygen, and two with steam. (The bottles are hot 
enough to prevent the steam condensing to water, and all five are at 
the same temperature.) Apply heat so that all shall be equally 
heated, the three different substances expand equally. Cool equally, 
the contents contract equally. Apply equal pressure to all five, each 
is equally affected. Diminish pressure equally, each portion of the 
three substances equally expands. Gases (practically steam is a gas, 
it is simply not a permanent gas) thus similarly affected must be, 
physically, similarly constructed or constituted (a law which will 
again be referred to, on page 54) ; each bottle must contain the 
same number of particles or molecules, and at any one temperature 
and pressure the molecules in each must be equally distant from 
each other. We do not know what actual number or distance, but 
whatever the number and distance it is the same for each bottle. 
Say that one million is the number, then we shall have a million of 
molecules in the first hydrogen bottle, a million in the second, a 
million in the oxygen bottle, and a million in each of the steam 
bottles. AVe will cause chemical combination between the two mil- 
lions of hydrogen molecules and one million of oxygen molecules, 
producing (as we have seen) two millions of steam molecules, hav- 
ing the properties already stated. But a molecule of steam contains 
an atom of oxygen. Hence two millions of steam molecules con- 
tain two millions of oxygen atoms, which two millions of oxygen 
atoms have been obtained from one million of oxygen molecules. 
Therefore each molecule of oxygen was a double structure — each 
molecule of oxygen contained two atoms of oxygen. As Clifford 
says, " you cannot put 50 horses into 100 stables, so that there shall 
be exactly the same amount of horse in each stable ; but you can 
divide 50 pairs of horses among 100 stables." 

Thus much respecting the constitution of gaseous or vaporous 
matter. Our knowledge of the constitution of liquid and solid mat- 
ter is still more limited. 

With regard to the notation of the subject, it will be sufficient to 
state here that while a symbol usefully represents one volume of any 
gas, a formula of any gas or vapor represents two volumes. By re- 
membering this general rub 1 we may, by looking at a formula, tell 
how many volumes of constituents were concerned in the formation 
of a compound, and therefore what amount of condensation, if an v. 
occurred during the act of formation. By thus reading and inter- 
preting the formula for water, H 9 0, we see that two volumes of 
Steam (at any temperature) may be obtained from two volumes of 
hydrogen and one volume of oxygen (at the same temperature), and 



46 GENEEAL PRINCIPLES OF 

thus that the extent of condensation when hydrogen and oxygen 
(at a stated temperature) unite to form gaseous water (at the same 
temperature) is from three to two. This subject will again be 
treated of in connection with those of Chemical Combination and 
the Specific Gravity of Gases. 

Further Remarks on General Chemical Notation. 
We may now take an experiment already made as an additional 
example of chemical action, and describe the simplest way of express- 
ing the same by notation. When two volumes of hydrogen and one 
of oxygen were caused to combine, the production of flame and noise 
proved that chemical action of some kind had taken place ; had the 
experiment been performed in dry vessels, evidence of the precise 
action would have been found in the bedewment or moisture produced 
by the condensation of the water on the sides of the tube. Similar 
evidence was aiforded on holding a cool glass surface over the hydro- 
gen-flame. The action is expressed in the following equation : — 

2H 2 -f0 2 = 2ILO. 

Instead of an equation, the following diagram may be employed : — ■ 
2H JH 




H 2 

The foregoing aggregation of symbols or short-hand characters, or 
formula, H 2 0, is, then, a convenient picture of the facts that have 
already come before us, viz., that water is formed of the elements 
hydrogen, H, and oxygen, ; moreover, that it is formed of two 
measures or volumes of hydrogen, H 2 , to one of oxygen, ; and, 
thirdly, that the molecule of water (H 2 0) is formed of two atoms of 
hydrogen (H 2 ) and one of oxygen (0). The formula also fulfils the 
fourth function of indicating that the two volumes of hydrogen and 
one of oxygen in combining condensed to two volumes of steam. 
That the resulting bulk of steam afterwards shrunk most consider- 
ably in condensing to water is another matter altogether, a physical 
and not a chemical result, and due to the approximation of the mole- 
cules of water after formation. 

Another experiment already performed, illustrating the character 
of the manifestations of chemical force (symbolically noted as fol- 
lows), was that in which the red-hot carbon of wood was plunged 
into oxygen. The evidence of chemical action in that case was the 
sudden inflammation of the carbonaceous extremity of the wood. 
The particles of carbon and oxygen, having intense attraction or 
affinity for each other at that temperature, rush together so impetu- 
ously as suddenly to produce a large additional quantity of heat, 
an amount sufficient to cause the particles to emit an intense white 



CHEMICAL PHILOSOPHY. 47 

light. The action between carbon and oxygen is expressed on paper 
in either of the following ways — (C 2 -f 20 2 = 2C0 2 ) : — 

f c ^ co 2 

10. 




C0 2 is the formula of the well-known gaseous body commonly 
termed carbonic acid gas. 

The reader should here draw for himself equations or dia- 
grams similar to those on page 46, and thus show the formation 
of the three bodies he has already produced — namely, phosphoric 
anhydride (P 2 5 ), sulphurous acid gas (S0 2 ), and iodide of iron 
(Fel 2 ), submitting the same, if possible, to a tutor or other 
authority to assure himself of their correctness. 

Note. — In the foregoing experiments several illustrations occur 
of the formation of compounds having the gaseous, liquid, and 
solid conditions, in one of which three forms all matter in the uni- 
verse apparently exists. 

Laws of Chemical Combination (by Weight). 
Chemistry as a science is little more than a hundred years old, 
though very many of the facts and operations we now term chemical 
have been known as isolated items of knowledge for centuries. Thus, 
the ancient Egyptians made glass, vitriol, soap, and vinegar ; and the 
Greeks started the idea that matter was composed of a few elements, 
imagining earth, air, fire, and water to be elements. But the great 
general principles which interlace and bind together separate facts, 
those which from their extensive application and importance are de- 
nominated laws, have all been brought to light since the year 1770. 

First Law relating to Chemical Combinations. 
Between 1785 and 1800, Bryan Higgins, William Higgins, Wenzel 
Kichter, and Proust made analyses and researches which led up to 
the following generalizations : When compounds unite to form defi- 
nite chemical substances, they always combine in the same proportions. 
The curious character of this fact could but be most striking, and 
indeed is so now, to the mind receiving it for the first time. Thus 
tmter (a compound) added to quicklime (a compound) gives slaked 
lime, a perfectly definite chemical substance. But whereas sand and 
water, sugar and water, sand and sugar, and such mixtures may be 
obtained by adding together the ingredients in any proportions what- 
ever, say 90 of sugar and 10 of sand, or 10 of sugar and 90 of sand, 
slaked lime (say 100 parts) invariably results from the combination 
Of 75| of quicklime and '24\ of water. If a larger proportion than 
75f per cent, of quicklime be employed, the excess remains as quick- 



48 GENERAL PRINCIPLES OF 

lime mixed with the slaked lime 5 and if more than 24£ per cent, of 
water be used, an excess of water remains with the slaked lime and 
evaporates if the mixture be exposed to the air. Dalton discovered 
that when elements unite to form a definite substance, they, like 
compounds, always combine in the same proportions ; and he was 
the first to set forth the law in a manner which was at once clear 
and comprehensive enough to include the former generalization. 
Thus :— 

A definite compound always contains the same elements in the 
same proportions. 

Take another example. Common salt always contains 39^ per 
cent, of the metal sodium to 60§ of chlorine, and water always 89 of 
oxygen and 11 per cent, of hydrogen (more exactly 88.89 to 11.11). 
As with quicklime and water, so with the chlorine and sodium, and 
the constituents of many (not all) chemical compounds ; in such 
cases if either be added to the other in any quantity beyond stated 
proportions, the excess plays no part whatever in the act of combi- 
nation. (In some cases, as will be seen directly, excess of either 
plays a very simple but very remarkable part.) In short, whether 
a compound be made directly from its elements, or by the combina- 
tion of other compounds, or indirectly as one of two products of the 
action of substances chemically on each other, whatever be its ori- 
gin, if it is a definite compound it always contains the same ele- 
ments in the same proportions. 

Second Law relating to Chemical Combinations. 
Dalton further made such experimental researches as enabled him 
to lay down a second great law. He found that, while many sub- 
stances only united chemically in one proportion, others combined in 
two or even more, and he studied several such naturally related 
bodies. He found that while carbonic oxide (a gas formed when 
charcoal is burned with an insufficient supply of air) contains such 
a proportional weight of carbon and oxygen as is represented by (to 
use the simplest figures) 3 and 4, carbonic acid (a gas formed when 
charcoal is burned with excess of air) contains 3 of carbon to ex- 
actly twice 4 of oxygen. He proved that a similar relation existed 
between two compounds of carbon and hydrogen, and between a 
cluster of compounds of nitrogen and oxygen. The first of the 
latter, to a given quantity of nitrogen, contains a certain proportion 
of oxygen ; the next, to the same quantity of nitrogen, has exactly 
twice the proportion of oxygen : and the others have exactly three, 
four, and five times as much oxygen as the first, the quantity of 
nitrogen remaining the same throughout. Dalton thus generalized 
these facts : — 

When two elements unite in more than one proportion, the re- 
sulting compounds contain, to a constant proportion of one ele- 
ment, simple multiple proportions of the other — or the weights of 
the constituent elements bear some similar simple relations to each 
other. 



CHEMICAL PHILOSOPHY. 49 

Thus carbonic oxide gas is a definite compound always containing 
iixed proportions of carbon and oxygen, and carbonic acid gas is 
also a definite compound always containing fixed proportions of 
carbon and oxygen. Both thus obey the first law of combination. 
But whereas carbonic oxide contains, or may be made from, 30 parts 
(ounces, grains, or other weights) of carbon and 40 of oxygen, car- 
bonic acid contains, or may be made from, 30 parts of carbon and 
exactly twice 40 of oxygen. 

This second law cannot but be as striking as the first when fresh- 
ly unveiled to the mind. Sand and sugar, or any substances which 
do not act chemically on each other, may be mixed in the propor- 
tions of 30 to 40, 30 to 80, 30 to 60, or any other quantities : but if 
an attempt be made to burn 30 parts of carbon in 60 of oxygen, the 
elements will themselves naturally assert their own special com- 
bining powers, and refuse, so to say, to unite in these proportions : 
the 30 of carbon will first combine with 40 of oxygen and form 70 
of carbonic oxide, and this gas, which, had it the opportunity, would 
combine with 40 more of oxygen and form carbonic acid gas, find- 
ing only half that quantity, namely, 20, of oxygen present, contents 
itself by one-half (that is, 35 of carbonic oxide), accepting the 20 of 
oxygen and becoming carbonic acid gas, while the other half re- 
mains as carbonic oxide. This is a most wonderful fact. Again, 
if 30 parts of carbon be burnt in more than 80, say 85, of oxygen, 
only 80 will be used, the other 5 remaining as oxygen merely mixed 
with the resulting carbonic acid gas. If we attempt to burn 30 
parts of carbon in less than 40 of oxygen, the oxygen will take up 
three-fourths its weight of carbon and form carbonic oxide, while 
the excess of carbon will remain as carbon. 

Recapitulation. 
Nature does not always permit man to mix things in any propor- 
tions he pleases. She does sometimes. She does if he only stirs 
things together, or if he only uses the attractions of adhesion or co- 
hesion in binding the materials together ; but if he employs chem- 
ical attraction, she restricts him to special proportions. That is to 
say, if the things mixed do not attack one another or intimately 
combine, then admixture may be effected in any proportion ; and 
the mixture is a mere mixture having the mean properties of its 
components. Examples of such mixtures are seen in compound 
plasters, pill-masses, confections, and plum-puddings. But if the 
things do unite to form, not a mere mixture having the mean prop- 
erties of its components, bat a compound having new and distinct 
and definite characters of its own, then nature does not permit man 
to mix the things in any proportion he pleases. The proportion is 
one fixed and constant; and if he substitutes proportions of his own, 
the things unite in the proportions fixed by nature, and the excess 
he has added either remains in its original uncombined condition. 
or it combines with the compound already produced to form a sec- 
ond difj'cfait compound. Any one compound, that is, the same 
compound, always contains the same elements in the same propor- 
tions, and can only be made from the same elements in the same 



50 GENERAL PRINCIPLES OF 

proportions. An attempt to mix the same elements in other pro- 
portions would result in one of two failures, namely, either the 
extra proportion would remain free and uncombined, or it would 
combine and convert the first compound, or a portion of it, into a 
different compound. The fresh compound thus produced, like the 
first, and indeed like all definite compounds, of course always con- 
tains the same elements in the same proportions. 

In short (law 1) any definite compound always contains the same 
elements in the same proportions, and (law 2) any two elements 
uniting in more than one proportion unite in multiples of that pro- 
portion, and produce so many different definite compounds, Tak- 
ing hydrogen as uniting in proportions of 1, oxygen unites in pro- 
portions of 16 — that is, 16, twice 16, thrice 16, and so on, never in 
intermediate proportions. Carbon unites in proportions of 12, sul- 
phur of 32, chlorine of 35J. And every other element has its com- 
bining proportion fixed by nature. 

The student of chemistry is recommended to accept these two 
great natural facts, great enough to be dignified by the name of 
laws, in all their inherent solidity and simplicity. Of course, he 
will wonder why substances should combine, chemically, only in 
fixed proportions when forming a definite body, and ichy, when a 
substance combines in more than one proportion to form different 
compound bodies, the proportions should only be multiple propor- 
tions ; and an extremely ingenious and useful explanation has been 
suggested by Dalton (see the following paragraphs on the theory 
that matter is built up of atoms) 5 but man has not yet succeeded 
in so questioning nature as to gain from her a satisfactory answer 
to such questions ; hence, until he does succeed, any hypothesis, 
such as Dalton' s, should be held intelligently but loosely. The 
facts themselves, however, should be grasped with the student" s 
utmost tenacity. 

Third Law relating to Chemical Combination. 
Careful consideration of the foregoing two great laws has 
suggested an important truth sometimes termed The Law of 
Chemical Combination, namely : The proportions in which tico 
elements unite with a third are the proportions {or simple mul- 
tiples or submultiples of the proportions*) in which they unite with 
each other. Thus oxygen in proportions of 16 unites with 
hydrogen, and carbon in proportions of 12 unites with hydro- 
gen ; therefore 16 and 12 are the proportions in which oxygen 
and carbon will unite with each other.* 



* See Axiom 1 in Hawtrey's fascinating " Introduction to the Ele- 
ments of Euclid," Longmans & Co., London, 2s. QcL, a book strongly 
recommended to any chemical student who is not familiar with the 
mode of reasoning commonly termed geometrical. 



CHEMICAL PHILOSOPHY. 51 

The Atomic Theory. 

The laws which Dal ton (1803 to 1808) so largely aided to unveil 
— two grand and wonderful truths — he explained and correlated by 
a simple and beautiful hypothesis. Bolton suggested that matter 
was not infinitely divisible, but composed of minute particles or 
atoms having an invariable character. In the words of Wurtz, " To 
an old and vague notion he attached an exact meaning by supposing 
that the atoms of each kind of matter possess a constant weight, and 
that combination between two kinds of matter takes place not by pene- 
tration of their substance, bid by juxtaposition of their atoms." 

Thus under this hypothesis, or atomic theory as it is generally 
termed, carbonic oxide is a definite compound always containing 
the same elements in the same proportions, because each particle of 
it is composed of an atom of carbon and an atom of oxygen chemi- 
cally united, the weights of the atoms being in the proportion of 3 
and 4, that is, having a constant weight of 12 and 16, as we now 
believe. Carbonic acid gas is also a definite compound always con- 
taining the same elements in the same proportions, and the propor- 
tion of oxygen is just double that in carbonic oxide, because each 
particle of it is composed of an atom of carbon (weighing 12) and 
two atoms of oxygen (each weighing 16). 



Imaginary pictures of molecules of carbonic oxide gas and carbonic acid gas.* 

Again, the facts that with 12 of carbon oxygen unites in the pro- 
portion of 16, or a multiple of 16 ; that with 12 of carbon sulphur 
unites in the proportion of 32, or a multiple of 32 (the liquid known 
as clisulphide of carbon is a chemical compound of 12 of carbon to 
twice 32 of sulphur) ; and, thirdly, that oxygen and sulphur unite 
in proportions of 16 and 32, are at once explained on the assump- 
tion that these elements exist in atoms which have the respective 
weights mentioned. Existing in indivisible particles (atoms) which 
weigh 16, 12, and 32, oxygen, carbon, and sulphur must unite in 
indivisible weights of 16, 12, and 32. 

Atomic Weights. 

What has just been stated respecting two or three elements is 
true of all the elements. It is a fact, that, when elements unite 
with one another in the peculiar and intimate manner termed chem- 

* The size of atoms, their shape, their absolute weight — whether or 
not they are in actual contact — whether or not they arc fixed in rela- 
tion to each other, free to move about each other, or in a constant slate 
of motion— and whether or not the chemical force actuates them as the 
force of gravitation influences our earth, and moon, and solar systems, 
arc matters oi* which at present we know almost nothing. The two 
pictures are not intended to convey any impression that the following 
ibrmulic do not give: CO or OC, OCO or OOC or COO or CO* 



52 GENERAL PRINCIPLES OP 

ical, they do not combine in the haphazard proportions of a mere 
mixture, but in one fixed and constant proportion. Such propor- 
tions or weights represent, according to Dalton, the weights of their 
atoms. Oxygen unites with other elements in proportions of 16, 
therefore 16 is the weight of the atom of oxygen. Chlorine unites 
with other elements in proportions of 35J, therefore 35J is the 
atomic weight of chlorine. And for a similar reason the atomic 
weights of hydrogen will be 1, carbon 12, sulphur 32, nitrogen 14, 
and iodine 127. Of course it will be understood that these are the 
relative weights of atoms, for we cannot know the absolute weights. 
All that is known is that the chlorine atom, for instance, is 35.5 
times as heavy as the hydrogen atom, whatever the absolute weight 
of the latter may be, and the iodine atom 127 times as heavy. The 
quantity of metal which with 35.5 of chlorine will form a chloride, 
and with twice 35.5 a second chloride (dichloride or bichloride), will 
require 127 of iodine to form an iodide, and twice 127 of iodine to 
form a second iodide (a diniodide or biniodide).* In other words, 
the atomic weight of an element is the ratio of the weight, quantity 
of matter, or mass of an atom to the weight, quantity of matter, or 
mass of an atom of hydrogen. 

Note on Notatioji. — A fourth function of a symbol is to represent 
atomic weight. Thus the symbols II, CI, O, etc., not only perform 
the office of representing (a) names, (b) single volumes, and (c) sin- 
gle atoms, but (d) definite weights of the respective elements. 

H = 1, CI = 35.5, 0=16,1 = 127, N = 14, K = 39, etc. 

Laws of Chemical Combination (by Volume). 

In 1809 Gay-Lussac showed it to be a fact that when gaseous ele- 
ments unite with one another in the intimate manner termed chem- 
ical, they do not combine in the haphazard proportions (that is, pro- 
portions by measure or volume) of a mere mixture, but in constant 
proportions in the case of any single definite compound, and in sim- 
ple multiple proportions in cases where two elements form more 
than one definite compound. He thus proved that the laws respect- 
ing the constancy of weight with which elements combine hold good 
with reference to volume, at all events in those cases in which ele- 
ments exist in or can be made to assume the gaseous condition. A 
volume of hydrogen gas and an equal one of chlorine gas give hy- 
drochloric acid gas. Two volumes of hydrogen and one of oxygen 
give water-vapor or steam. Such volumes or simple multiples are 
alone the proportions by bulk in which elements combine. If any 
excess of either gas be mixed and combination attempted, only the 
stated proportions really combine, the excess remaining unaltered. 
Further, following Gay-Lussac, on weighing these similar and equal 

* Only the atomic weights of the above and a few of the chief metal- 
lic elements need be committed to memory ; others can be sought out 
as occasion may require. A complete Table of combining proportions 
of elements, or Atomic Weights, is given at the end of the volume. 



CTIEMICAT, PHILOSOPHY. 53 

volumes of hydrogen, chlorine, and oxygen, we find that the chlo- 
rine is 35.5 times as heavy as hydrogen, and oxygen 16 times as 
heavy as hydrogen. 

In 1811 and 1814, Avogadro and Ampere, reasoning on the fact 
that all gases are similarly affected by variations of pressure (Boyle, 
1662, verified by Mariotte) and temperature (Charles), concluded 
that all gases must be similarly constituted — similarity in proper- 
ties always indicating similarity in character or nature ; in other 
words, that, if equal volumes of gases be taken under like conditions, 
each will contain the same number of molecules, similar in size and 
equally distant apart. The deduction is obvious. The weights of 
molecules of gaseous elements {that is, pairs of atoms, and therefore 
of atoms themselves) must differ to the extent that the weights of equal 
volumes of those elements differ. Equal volumes of hydrogen, chlo- 
rine, and oxygen, weighing respectively 1, 35.5, and 16, and each 
of these volumes containing an equal number of molecules, each 
formed of two atoms, it follows that the relative weights of the 
atoms will be 1, 35.5, and 16. 

It will thus be seen that the weight of the volume in which an 
element combines, and the actual weight in which it combines, irre- 
spective of volume, are identical. For instance, we should find by 
experiment that, as a simple matter of fact, oxygen unites with other 
elements in proportions of 16 by weight, while hydrogen combines 
in proportions of 1. Turning, then, to experiments on the volumes 
in which hydrogen or oxygen combine, and having ascertained those 
volumes, and then having weighed them, we should find that the 
oxygen volume weighs 16, while the hydrogen weighs 1. In com- 
pounds in which proportions of 1 grain of hydrogen were found, 
oxygen would be found in proportions of 16 grains. In gaseous 
compounds in which hydrogen existed in proportions of, say, 27 
ounces by measure, oxygen would be found in proportions of 27 
ounces by measure ; the 27 ounces of hydrogen would be found to 
weigh 1 grain, and the 27 ounces of oxygen to weigh 16 grains. 

Thus the two great facts or laws respecting chemical compounds 
which Dal ton laid down by ascertaining the exact weights in which 
bodies combine, Gay-Lussac confirmed by experiments on the exact 
volumes in which elements combine. Further, Gay-Lussac's exper- 
iments and Avogadro 1 s reasoning strongly supported Dal ton's theory 
of atoms. 

Recapitulation. 

What are atomic weights or combining weight*? First, they are 
represented by the smallest proportion (relative to 1 part of hydro- 
gen) in which an element migrates from compound to compound. 
Thus 1 part by weight of hydrogen can be eliminated from L8 sim- 
ilar parts of water by action of certain metals, leaving I oi' hydrogen 
and 16 of oxygen combined with the metal. From the latter com- 
pound 1 more of hydrogen is eliminated by a second experiment with 
more metal, leaving 16 of oxygen combined with the metal. In these 
and oilier well-known reactions 16 parts of oxygen take part in the 
various operations; 16, therefore, is the probable atomic weight oi' 
oxygen: and so with other elements and radicals. Secondly, the 



54 GENERAL PRINCIPLES OF 

weights of the atoms, or the atomic weights, of the gaseous elements 
already studied, must differ from each other to the extent that equal 
volumes of those elements differ in weight. For equal volumes of an 
element contain an equal number of molecules equal in size (Avoga- 
dro's and Ampere's conclusion), and each molecule is composed of two 
atoms ; so that equal volumes of elements contain an equal number 
of atoms. Now, bulk for bulk, chlorine is thirty-five and a half 
(35.5) times as heavy as hydrogen ; so that the molecule of chlorine 
must be 35.5 times the weight of the molecule of hydrogen ; for 
molecules are equal in bulk. And as the molecules of chlorine and 
hydrogen contain two atoms each, the atom of chlorine must be 35.5 
times as heavy as that of hydrogen. The actual Aveight of atoms 
can never be ascertained, but that is of little consequence if we can 
only determine, with exactitude, their comparative weights. Com- 
paring, then, all atomic weights, sometimes obscurely termed equiv- 
alents, with each other, and selecting hydrogen as the standard of 
comparison (because it is the lightest body known, and therefore, 
probably, will have the smallest atomic weight), and assigning to it 
the numoer 1, we see that the atomic weight of chlorine will be 
represented by the number 35.5. By parity of reasoning the atomic 
weight of oxygen is 16 ; for oxygen is found, by experiment, to bo 
16 times as heavy as hydrogen. Similarly the atomic weight of 
nitrogen is found to be 14. The atomic weight of carbon is 12 — not 
because its vapor has been proved to be 12 times as heavy as hydro- 
gen, for it has never yet been converted into the gaseous state, but 
because no gaseous compound of carbon, which has been analyzed, 
has been found to contain in 2 volumes (one of which, if hydrogen, 
would weigh 1 part) less than 12 parts of carbon. 

By thus weighing equal volumes of gaseous elements, or equal 
volumes of gaseous compounds of non-volatile elements, and ascer- 
taining b} T analysis the proportion of the non-volatile element whose 
atomic weight is being sought to the volatile element whose atomic- 
weight is known, the atomic weights of a large number of the ele- 
ments have been determined. Some of the elements, however, do 
not form volatile compounds of any kind ; the stated atomic weights 
of these elements, therefore, are at present simply the proportions by 
weight in which they combine with or displace elements whose atomic 
weights have been determined, the proportion being in most cases 
checked by isomorphic considerations and the relation of the element 
to other forces, especially heat.* ( Vide infra.) 

* Isomorphous bodies (from lone, isos, equal, and fJ-opfyrj, morphe, form) 
are those which are similar in the shape of their crystals. The iden- 
tity in crystalline form is so commonly associated with similarity of 
constitution that non-crystalline substances resembling each other in 
structure are often regarded as isomorphous. When one element 
unites with another in more than one proportion, and its atomic 
weight is so far uncertain, the isomorphism of either of its com- 
pounds with some other compound of known constitution is usually 
accepted as decisive evidence as to which proportion is atomic. The 
specific heat of elements will be treated of subsequently. 



CHEMICAL PHILOSOPHY. 55 

Molecular Weight and Molecular Yolume. 
The weight of the molecule is simply the sum of the weights of its 
atoms ; thus 

H 2 = 2; 2 = 32; Cl 2 = 71; H 2 = 18; HC1 = 36.5. 

Molecular Volume. — If the quantities just mentioned be weighed 
out (in grains or other weights), or if the molecular weight of any 
gases or'liquids be taken and exposed to similar (high) temperatures 
and pressures, they will all be found to occupy the same volume. 
Conversely, if equal volumes of gases or vapors be measured out, 
and then the whole weighed, the resulting figures (all referred to 2 
of hydrogen as a starting-point or standard) are the molecular 
weights of the respective substances. Thus a volume of hydrogen 
(about 54 fluidounces), which, at a temperature of, say, 300° F. or 
400° F., and common atmospheric pressure, would weigh 2 grains, 
would in the case of vapor of water (steam) weigh 18 grains. 
Hence we are justified in considering, indeed compelled to con- 
sider, the molecule of water to contain two atoms of hydrogen 
(=2) and one of oxygen (= 16), and its formula to be II 2 (= 18), 
and not H 4 2 , in which case its vapor would be twice as heavy as it 
really is found to be. 

Construction of Formulae. — The composition of hydrochloric acid 
(HC1), water (H 2 0), ammonia (NH 3 ), carbonic acid gas (C0 2 ), or 
any other compound, as well as the weight of an element that may 
be concerned in its formation, cansaot be ascertained by actual ex- 
periment until the student is far advanced in practical chemistry — ■ 
until he is able to analyze not only qualitatively, but, by help of a 
balance, quantitatively. The percentage composition of a substance 
having been determined by quantitative analysis, its formula is con- 
structed by aid of the foregoing and other theoretical considerations. 
The correctness of such formulae can be verified by expert analysts, 
but must be taken for granted by learners. This subject will again 
be referred to in the latter part of this Manual. 

QUANTIVALENCE OF ATOMS. 

Turning from the weights of atoms, their value may now be con- 
sidered ; their quantivalence may be stated. The chemical value of 
atoms in relation to each other may be compared to the exchangeable 
value of coins. As compared with a penny (1(/.) a groat (4</.) is 
four-valued; as compared with hydrogen, carbon is quadrivalent. 
Here again hydrogen is conveniently adopted as the standard of 
comparison. An atom of oxygen in its relations to an atom of 
hydrogen is bivalent (biv'-a-lent ; of double worth, from bis, twice, 
and valens, being worth); an atom of it will displace two atoms of 
hydrogen, or combine with the same number; nitrogen is usually 
trivalent (trivia-lent; from fres, three, and valens) ; and carbon, 
ouad-riv'-a-lent (from quatuor, four, or qita/er, four times, and vah ns). 
Chlorine, iodine, and bromine, as well as potassium, sodium, and sil- 
ver among the metals, are, like hydrogen, univalent (u-niv'-a-lent ; 



56 GENERAL PRINCIPLES OF 

from units, one, and valens). Barium, strontium, calcium, magne- 
sium, zinc, cadmium, mercury, and copper, like oxygen, are biva- 
lent. Phosphorus, arsenium, antimony, and bismuth, like nitrogen, 
usually exhibit trivalent properties ; but the composition of certain 
compounds of these five elements shows that the several atoms are 
sometimes quinquivalent (quin-quiv / -a-lent ; quinquies, five times, 
and valens). Gold and boron are trivalent. Silicon (the character- 
istic element of flint and sand), tin, aluminium, platinum, and lead 
resemble carbon in being quadrivalent. Sulphur, chromium, man- 
ganese, iron, cobalt, and nickel are sexivalent (sex-iv'-a-lent ; from 
sex, six, or sexies, six times, and valens), but frequently exert only 
bivalent, trivalent, or quadrivalent activity. This quant ivalence 
(quant-iv'-a-lence ; from quantitas, quantity, and valens), also 
termed atomicity (maximum quantivalence), dynamicity, and 
equivalence of elements, may be ascertained at any time on refer- 
ring to the table of the Elements at the end of this volume, where 
Roman numerals, i, n, in, iv, v, vi, are attached to the symbols of 
each element to indicate atomic univalence, bivalence, trivalence, 
quadrivalence, quinquivalence, or sexivalence. Dashes (H / , .0 // , 
N T/// ) similar to those used in accentuating words are often used 
instead of figures in expressing quantivalence. The quantivalence 
of elements, as they one after another come under notice, should be 
carefully committed to memory ; for the composition of compounds 
can often be thereby predicated with accuracy and remembered with 
ease. For instance, the hydrogen compounds of chlorine, CV, oxy- 
gon, // , nitrogen, N /// , and carbon, C //// , will be respectively 
ll'Cl'. H',0", H'gN'", and Wfi"",— one univalent atom, H', 
balancing or saturating one univalent atom, CV ; two univalent 
atoms, H^, and one bivalent atom, // , saturating each other 5 three 
univalent atoms, IV 3 , and one atom having trivalent activity, N //V , 
saturating each other ; and four univalent atoms, H' 4 , and one quad- 
rivalent atom, C //// , saturating each other. Carbonic acid gas, 
C ,v O n 2 , again, is a saturated molecule containing one quadrivalent 
and two bivalent atoms. 

The subject of quantivalence will be further explained after the 
first six metals have been studied, when abundant illustrations of 
it will have occurred. 



DEFINITIONS. 



Chemistry is the study of the chemical force. 

The Chemical Force, like other forces, cannot itself be described, 
for, like them, it is only known by its effects. It is distinguished 
from other forces by the facts that (a) it produces an entire change 
of properties in the bodies on which it is exerted, and that (b) it is 
exerted only between definite weights and volumes of matter. Like 
the force of cohesion, which is the name given to the attraction 
which molecules have for each other, and which is great in solids, 
small in liquids, and apparently absent in gases, and like the force 



CHEMICAL PHILOSOPHY. 57 

of adhesion, which is the name given to the attraction which a mass 
of molecules has for another mass, the chemical force acts only 
within immeasurable distances : indeed, inasmuch as the chemical 
force appears to reside in atoms, that is to say, is exerted inside a 
molecule, while all other forces affect entire molecules, the chemical 
force may be said to be distinguished (c) by being exerted within a 
smaller distance than that at which any other force is exerted. 

An Element is a substance which cannot by any known means be 
resolved into any simpler form of matter. 

An Atom of any element is a particle so small that it undergoes 
no further subdivision in chemical transformations. 

A Molecule is the smallest particle of matter that can exist in a 
free state. 

A mere Mixture of substances is one in which each ingredient re- 
tains its properties. 

A Chemical Compound is one in which definite weights of con- 
stituents have combined, and during combination have undergone 
an entire change of properties. A " compound " in pharmacy is an 
intimate mixture of substances, but still only a mixture ; it is not a 
chemical compound, the ingredients have not entered into chemical 
union or combination. 

Combustion is a variety of chemical combination, a variety in 
which the chemical union is sufficiently intense to produce heat 
and, generally, light. 

The Law of Diffusion is one under which gases mix with each 
other at a rate which is in inverse proportion to the square root of 
their relative weights ; that is, irrespective of and even in spite of 
their comparative lightness or heaviness. 

A Chemical Symbol is a capital letter, or a capital and one small 
letter. It has four functions, namely : — 

1. It is short-hand for the name of the element. 

2. It represents one atom of the element. 

3. It stands for a constant weight of the element — the atomic 

weight or combining weight. 

4. Symbols represent single and equal volumes of gaseous ele- 

ments. 
A Chemical Formula represents a molecule either of an element 
or of a compound. It has four other functions : — 

1. It indicates at a glance the names of the elements in the 

molecule. 

2. Its symbol or symbols, together with a small figure attached 

to the foot of any symbol, show the number of atoms in the 
molecule. 

3. It stands for a constant weight of a compound — the molecular 

weight — the sum of the combining weights or of the weights 
of the atoms in the molecule. 

4. Tt represents two volumes of the substance, if volatilizable, 

in the state of gas or vapor, and the number ol' volumes 
of gaseous elements from which two volumes of any gas- 
eous compound were obtained. 



58 GENERAL PRINCIPLES OF 

A Chemical Equation or a Chemical Diagram is a collection of 
formulae and symbols so placed on paper as to form a picture or 
illustration of the state of things before and after that metathesis 
(interchange of atoms) of molecules which results in the formation 
of molecules of new substances. 

A Solid is a substance the molecules of which are more or less 
immobile, though probably not in absolute contact. 

A Liquid is a substance the molecules of which so freely move 
about each other that it readily assumes and retains the form of 
any vessel in which it is placed. 

A Gas is a substance the molecules of which are so far apart that 
they seem to have lost all attraction for each other, and, indeed, to 
have acquired the property of repulsion to such an extent that they 
are only prevented from receding to a still greater extent by the 
pressure of surrounding matter. Motion is especially characteristic 
of gaseous fluids. 

The Three Laws regulating Chemical Combination {either by 
weight or volume). 

First. A definite compound always contains the same elements 
and the same proportions of those elements — by weight or volume. 

Second. When two elements unite in more than one proportion, 
they do so in simple multiples of that proportion. 

Third. The proportions in which two elements unite with a third 
are the proportions in which they unite with each other. 

Atomic Weights are, first, the proportions in which elements are 
found to combine with each other by weight. (The figures showing 
these proportions are purely relative, but all chemists agree to make 
this relation fixed by giving the number 1 to hydrogen.) Secondly, 
they are the weights of equal volumes of elements in the state of gas 
(relative to 1 of hydrogen). 

Molecular Weights. — These are the weights of equal volumes of 
gases or vapors, under equal circumstances of temperature and pres- 
sure, and relative not to 1 but to 2 of hydrogen. In the case of non- 
volatile bodies, molecular weight is deduced from the observed 
analogies of the bodies with those whose molecular weight admits 
of proof. The molecular weight of a compound is the sum of the 
atomic weights. 

Quant icaience of Atoms. — The observed power, force, or value 
for work of an atom — relative to 1 of hydrogen. 



The Learner is recommended to read the foregoing para- 
graphs on the General Principles of Chemical Philosophy 
carefully once or twice, then to study (experimentally, if 
possible) the following pages, returning to and reading over 
the General Principles from time to time until they are thor- 
oughly COMPREHENDED. 

Minor Principles and Generalizations will be found scattered 
throughout the following pages. 



CHEMICAL PHILOSOPHY. 59 

Students of pure chemistry, especially when fairly well acquainted 
with chemical facts, will also find the Principles of Chemistry, in- 
cluding the probable Constitution as distinguished from the mere 
Composition of Chemical Substances, amply set forth in Tilden's 
"Chemical Philosophy," one of Longman's series of "Text-books 
of Science." 

QUESTIONS AND EXERCISES. 

42. What do you understand by chemical action? Give ex- 
amples. 

43. How is chemical force distinguished from other forces ? 

44. Adduce evidence that elements exist in compounds ; that sul- 
phide of iron, for instance, still contains particles of sulphur and 
iron, though it possesses properties so different from those ele- 
ments. 

45. Define the term atom. 

46. What condition is essential for the manifestations of chemical 
force ? 

47. Can an atom exist in an uncombined state? and when are the 
atoms of an element most potent to enter into chemical combination? 

48. What is a molecule ? 

49. How may the results of chemical reactions be expressed on 
paper ? 

50. Enumerate the functions of a symbol. 

51. Give the additional functions of a chemical formula. 

52. Describe by a diagram or an equation the reaction which en- 
sues when red-hot charcoal is plunged into oxygen gas. 

53. Draw diagrams representing the formation of P 2 5 , S0 2 , and 
FeX 2 respectively. 

54. Enumerate the differences in the physical conditions of the 
molecules in a solid, a liquid, and a gas. 

55. State the law of constant proportions. 

56. State the law of multiple proportions. 

57. State the law of reciprocal proportions. 

58. Give illustrations of the above laws. 

59. Describe the origin and use of the atomic theory. 

60. What do you understand by the atomic weight, and the mole- 
cular weight of an element ? 

61. Representing the weight of an atom of hydrogen as 1, what 
will be the atomic weights of carbon, sulphur, nitrogen, ami iodine? 
Give reasons for considering the stated weights to be correct. 

02. In what proportion, by volume, do elements in the gaseous 
state chemically combine? 

63. What relation exists between the combining volumes of ele- 
ments in the gaseous state and their atomic weights? (Jive the ex- 
planation for this. 

64. Is there any difference between the molecular volume of a 
simple or of a compound gas? 

65. Define isomorphism. 

00. Explain the value of isomorphism as evidence of atomic 
weight. 



GO GENERAL PRINCIPLES OF CHEMICAL PHILOSOPHY. 

67. What is to be understood by the quanti valence of an element? 
Give examples of univalent, bivalent, trivalent, and quadrivalent 
atoms. 

68. How may the quanti valence of an element be expressed in its 
atomic symbol ? 

69. Give the formulas of two or three compounds in which the 
quantivalence of one atom is saturated by the combined quantiva- 
lence of others. 

The reader is also recommended to question himself, or be ques- 
tioned, on the "definitions" given on pages 56, 57, and 58. 



THE ELEMENTS AND THEIR COMPOUNDS. 

Having thus obtained a general idea of the nature of such ele- 
ments as have especial interest for the medical and pharmaceutical 
student, and which indeed are all with which any student of chem- 
istry should at present occupy his attention, we may pass on to con- 
sider in detail the relations of the elements to each other. The ele- 
ments themselves, in the free condition, are seldom used in medicine, 
being nearly always associated — bound together by the chemical 
force •, in this combined condition, therefore, they must be studied, 
inorganic combinations first, organic afterwards. The inorganic 
compounds may, as a rule, be regarded as containing two parts or 
roots, two radicals ; the one usually metallic, or, to speak more gen- 
erally, basylous ; the other commonly a non-metallic, simple or com- 
plex, acidulous radical. The basylous radicals, or metals, will be 
considered in the immediately succeeding pages, then the acidulous 
radicals. Each radical will be studied from two points of view, the 
synthetical and the analytical ; that is to say, the properties of an 
element on which the preparation of its compounds depends Avill be 
illustrated by descriptions of actual experiments, and thus the prin- 
ciples of chemistry, and their application to medicine and pharmacy, 
be simultaneously learnt ; then the reactions by which the element 
is detected, though combined with other substances, will be performed, 
and so the student will be instructed in qualitative analysis. Syn- 
thetical and analytical reactions are, in truth, frequently identical, 
the object with which they are performed giving them synthetical 
interest on the one hand, or analytical interest on the other. 

A good knowledge of chemistry may be acquired synthetically by 
preparing considerable quantities of the salts of the different metals, 
or analytically by going through a course of pure qualitative anal- 
ysis. But the former plan demands a larger expenditure of time 
than most students have to spare, while under the latter system they 
generally lose sight of the synthetical interest which attaches to 
analytical reactions. Hence the more useful system, now offered, 
of studying each metal, etc., from both points of view, time being 
economized by the operator preparing only small specimens of 
compounds. 

Chemical synthesis and analysis, thoughtfully and conscientiously 
followed, without hurry and mere superficial consideration, but, of 



THE BASYLOUS RADICALS. — POTASSIUM. 61 

course, without undue expenditure of time, will insensibly carry 
the principles of chemistry into the mind, and fix them there 
indelibly. 



THE BASYLOUS RADICALS. 
POTASSIUM. 

Symbol K. Atomic weight 39. 
Formula K 2 . Probable molecular weight 78. 

Memoranda. — The chief sources of the potassium salts* are the 
chloride, found at Stassfurt, in Prussia, in the form of the mineral 
Camallite (KCl,MgCl 2 6H 2 0) ; the nitrate, found in soils, especially 
in warm countries ; and the compounds of potassium, existing in 
plants. Kainite, a double sulphate of potassium and magnesium, 
also occurs among the Stassfurt minerals. The vegetable salts of 
potassium are converted into carbonate (other salts are present) 
when the wood or other parts are burned to ashes. If the ashes 
be lixiviated with water, and the solution evaporated to dryness, 
the residue, when fused, constitutes crude potashes. The residue, 
calcined on the hearth of a reverberatory furnace till white, gives 
the product termed pearlash. Large quantities of carbonate are 
thus produced in North America and Russia, and, latterly, from 
the sugar-beet marc, in France. From the native chloride and from 
the carbonate purified by treating the pearlash with its own weight 
of distilled water, filtering and evaporating the solution until it 
thickens, and stirring constantly, "so as to form agranular salt" 
(Potassii Carbonas, U. S. P.), nearly all other compounds of potas- 
sium are made. Exceptions occur in cream of tartar (Potassii 
Bitartras, U. S. P.), which is the more or less purified natural 
potassium salt of the grape-vine, and in nitrate of potassium. Po- 
tassium is a constituent of between forty and fifty chemical or 
Galenical preparations of the Pharmacopoeias. 

Carbonate of potassium is a white crystalline or granular powder, 
insoluble in alcohol, very soluble in water, rapidly liquefying in the 
air through absorption of moisture, alkaline and caustic to the taste. 
It loses all water at a red heat. Potassii Carbonas Pvnis.V. S. P., 
is obtained by heating the bicarbonate to redness: the resulting 

k white anhydrous carbonate is converted into hydrous granular car- 
bonate by solution in water and evaporation until a dry granular 
salt remains. 
Preparation. — Potassium itself is isolated with some difficulty by 
distilling a mixture of its carbonate and charcoal. It rapidly 0x1- 
'"•"""""' " i """"" 1 "" " ! 



* The ill-defined term salt Includes most solid chemical substances, 
ut more especially those which assume a crystalline form. 
6 



62 THE BASYLOUS RADICALS. 

> 

eral naphtha, a liquid containing no oxygen. It crystallines in 
octahedra. 

Quantivalence. — The atom of potassium is univalent, K/, 

Reactions having (a) Synthetical asd (b) Analytical Interest. 

(a) r'///jfhc':crt/ Bract ions. 

These are actions utilized in manufacturing preparations of potas- 
sium. The word synthesis is from avvdeacg (sunthesis), a putting to- 
gether, as opposed to analysis, from ava/wu (analuo), I resolve. 

Hydrate of Potassium. Caustic Potash. 

First Synthetical Reaction. — Boil together, for a few minutes, 
in a test-tube, five or six grains of carbonate of potassium 
(K 2 C0 8 ) and a like quantity of slaked lime (Ca2HO) with a 
small quantity of water. Set the mixture aside in the test-tube 
rack till all solid matter has subsided. 

This liquid is a solution of caustic potash, or hydrate of potassium 
(KHO). Made of a prescribed strength (about 5 per cent. ; sp. gr. 
1.036), it forms the Liquor Potassai, U. S. P. 

The mixture is known to be boiled long enough when a little of 
the clear liquid, poured into another test-tube and warmed, gives no 
effervescence on the addition of an acid (sulphuric, hydrochloric, or 
acetic) — a test whose mode of action will be explained hereafter. 

In the United States Pharmacopoeia the carbonate of potassium 
for this operation is directed to be obtained by boiling a solution of 
the bicarbonate until effervescence ceases ; that is, until the bicar- 
bonate is almost entirely converted into carbonate. 

Best Method of expressing Decompositions . — This will be easy of 
comprehension if what has already been stated concerning symbols 
and formulas, on pages 31 to 42, has been carefully and thoughtfully 
considered. The best means of showing on paper the action which 
occurs when chemical substances attack each other is by the employ- 
ment either of equations or diagrams, setting forth the formulae of 
the molecules concerned in the reaction. In an equation the form- 
ulas of the salts used are written on one line, the sign of addition 
(+) intervening ; the sign of equality (=) follows, and then the 
formulae of the salts produced, also separated by a plus sign (-f-). 
Thus :— 

K 2 C0 3 + Ca2HO = 2KHO + CaC0 3 . 

In this reaction (the operation just performed) the metals of the 
molecules of the two salts change place : from K 2 C0 3 and Ca2IIO 
there are produced CaC0 3 and KHO (two molecules, 2KHO); from 
carbonate of potassium and hydrate of calcium there result car- 
bonate of calcium (the insoluble portion) and hydrate of potassium 
(in solution).* 

* If the student is already accustomed to the use of ordinary equa- 
tions, he may pass on to Note 1, on page 65. If not, the author would 
strongly recommend the temporary employment of diagrams for ex- 



HYDRATE OF POTASSIUM. 63 

In constructing a diagram or pictorial illustration of a chemical 
reaction (the reaction, for instance, just described), first the formulae 
of the salts used are written under each other on the left side of the 
leaf of a note-book, thus : — 

K 2 C0 3 



Ca2HO 

Such formulae are, in this Manual, always given with the descrip- 
tion of the reaction. Secondly, on the right is then written the 
formula of the chief substance produced, thus : — 

K 2 C0 3 KHO 



Ca2IIO 

Thirdly, the formation of this chief body under consideration, 
that is to say, both the origin of its elements and their destina- 
tion, is traced out by the help of brackets and letters, which show 
the source of the elements, and converging lines which suggest the 
approach and final union of the elements, thus : — 

k,co 8 I K — KII ° 




Ca2IIO 

At this stage (at other stages, perhaps, in other reactions) the 
reader's own intelligent power of thought and reflection must come 
into exercise. He must reason somewhat as follows : " I am con- 
verting, and entirely converting, a quantity of carbonate of potas- 
sium into hydrate of potassium. A molecule, the smallest quan tity 
I can picture on paper, of the carbonate of potassium (K 2 C0 3 ) con- 
tains, I am told, two atoms of potassium (K 2 ), and a molecule of the 
hydrate (KIIO), one atom (K). Therefore each molecule of the car- 
bonate (K 2 C0 3 ) will furnish two molecules of the hydrate (2KHO). 
Moreover, I notice that in the formula of a molecule of the hydrate 
of calcium (slaked lime) I employ, there are 2 of the 110 (that is, 

pressing chemical changes. Indeed, the occasional, it' not the regular, 
use of graphic equations or diagrams is of advantage* to all students. 
For while equation or diagram equally well records the formula of 
the sails concerned in the whole reaction, the diagram alone suggests 
the mode in which its writer believes the respective atoms to change 
their positions. In the paragraphs succeeding the above detailed ex- 
planations are given respecting the use and construction of diagrams. 



64 



THE BASYLOUS RADICALS. 



2H0), and this fact confirms me in the deduction that one molecule 
of the carbonate affords tivo molecules of the hydrate." The pupil 
will then amend his diagram, thus : — 

KC0 (K, — ^2KHO 



Ca2HO 



J2HO' 



Fourthly, the question as to what becomes of the other elements 
must be cleared up. Indeed, when the reader remembers that he is 
studying this reaction for the aid it affords- him in learning chemis- 
try, and not because he is desirous of manufacturing caustic potash, 
he will see that this latter part of the reaction is quite as important 
as the former. To complete the diagram, then, he must first know 
what other compound is produced and its formula. The context of 
his Manual will generally afford this information, or, after a little 
experience is acquired, analogies or his own knowledge will suggest 
correct formulas. In this case carbonate of calcium is produced, 
CaC0 3 . (This product is, in fact, precipitated chalk, together with 
any excess of slaked lime and any natural impurities in the slaked 
lime. Pure " precipitated chalk " is made by an analogous reaction 
described subsequently.) 

The source of the elements of the carbonate of calcium, and, 
finally, their union, must be indicated just as the source and mode 
of formation of the potash were indicated. That is to say, after the 
formula of this second substance produced (CaC0 3 ) is written on the 
right of the diagram, thus : — 



K 9 CO, 



fK, 



2KHO 



Ca2HO 



2HO 



CaCO, 



the source of its elements is shown by writing the symbols for those 
elements on the right of the bracket attached to the formula con- 
taining the symbols of the elements, thus : — 



K,CO a 



Ca2HO 




\ 2110 

I Ca 



2KII0 



CaCO, 



Lines converging from the symbols of these elements also, and unit- 
ing at the formula of the substance (CaC0 3 ), are then drawn, to sug^ 



HYDRATE OF POTASSIUM. 65 

gest approach of the atoms of the elements and their union to form 
a molecule of the compound. The diagram will now be complete, 
and will have been built up in the student's note-book, thus : — 



K,CO s 




KHO 



Ca2HO {g*°_ ^^ 

The formation of a third product or a fourth product would be 
indicated in a similar manner. 

Note 1. — It will be seen that the chief data required in making 
either equationary or diagrammatic notes of decompositions are the 
symbolic formulae of the various compounds employed and produced. 
These formulae are, in this Manual, given whenever necessary. 
Chemists obtain them in the first instance by help of quantitative 
analysis. By the same means is obtained a check on the proba- 
bilities respecting the relative number of molecules concerned in a 
reaction. 

Note 2. — While an equation or a diagram is an attempt to picture 
the reaction which ensues when molecules of different substances act 
upon one another, it necessarily only represents two or a minimum 
number of the molecules. The student will, of course, understand 
that what is true of these two or three molecules is true of the thou- 
sands or millions of molecules forming the mass or whole quantity 
of material on which he experiments. 

Note on Nomenclature. — Hydrates are bodies indirectly or 
directly derived from water by one-half of its hydrogen becom- 
ing displaced by an equivalent quantity of another radical. 
Thus, a piece of potassium thrown on to water (HHO) in- 
stantly liberates hydrogen, hydrate of potassium (KHO) being 
formed. The temperature produced at the same time is suffi- 
ciently high to cause ignition of the hydrogen, which burns 
with a purple flame (owing to the presence of a little vapor of 
potassium), while the hydrate of potassium remains dissolved 
in the bulk of the water. This radical or root or group of 
elements (HO), common to all hydrates, is sometimes termed 
hydroxyl. Water might be termed hydrate of hydrogen or 
hydroxylidc of hydrogen. 

Explanation. — With regard to the group of atoms repre- 
sented by the symbols C0 3 and 110, only a few words need be 
said here. The former (C0 3 ) is the grouping (root or radical) 
found in all the molecules of all carbonates ; it is termed the 
carbonic radical, and is as characteristic of the molecules of 
carbonates as potassium (K) is of the molecules oi' potassium 
6* 



THE METALLIC RADICALS. 



salts. HO (hydroxyl) is characteristic of all molecules of all 
hydrates. C0 3 is a bivalent root, HO is univalent ; hence the 
group of atoms represented by C0 3 is found united with two 
univalent atoms, as in carbonate of potassium, K. 2 CO b , or with 
one bivalent atom, as in carbonate of calcium, CaC0 3 ; and HO 
is found united in a single proportion with univalent atoms, as 
in a molecule of hydrate of potassium, KHO, or in double pro- 
portion with bivalent atoms, as in a molecule of hydrate of cal- 
cium, Ca2HO. The quantivalence of a metal has only to be 
learnt, and the formulae of its carbonate and hydrate are ascer- 
tained without seeing the formula of either. The formulae of 
all other metallic salts are constructed on the same principle. 
But, beyond committing to memory the formulae and quan- 
tivalence of the various groupings characteristic of carbonates, 
hydrates, nitrates, sulphates, acetates, etc. (see the following 
Table), special attention should not at present be devoted to 
the subject of the constitution of salts, but restricted to what 
may be called the metallic or basylous side of salts. The form- 
ulae and quantivalence of the chief acidulous groupings referred 
to, and the symbols and quantivalence of allied elementary bodies, 
are included in the following Table : — 

Formulae, and Quantivalence of Acidulous Radicals. 



W\ chlorides contain . 


. . CI 


" bromides " 


. . Br 


" iodides " 


. . I 


" cyanides " 


. . CX 


" hydrates " 


. . HO 


" nitrates " 


. ■ N0 3 


" chlorates " 


• • C10 3 


" acetates " 


. . C 2 H 3 2 


" oxides " 


. . 


" sulphides " 


. . s 


" sulphites " 


. . so, 


" sulphates " 


. . 80, 


" carbonates " 


• • CO3 


" oxalates " 


• . CA 


" tartrates " 


. . C 4 H 4 6 


" citrates " 


• • C 6 H 5 7 


" phosphates " 


. . P0 4 


" borates " 


• • B0 3 



Radicals. — The above elements and compounds are termed rad- 
icals, each being the common root (radix) in a series of salts. Why 
compound radicals (as N0 3 , S0 4 , P0 4 , etc.) differ in quantivalence 



SULPHURATED POTASH. 67 

cannot well be explained at present. Their constituent atoms doubt- 
less always exert the same amount of attractive force, nearly but 
not quite all this force being exerted in retaining the atoms in one 
group, and the remainder probably determining the quantivalence. 
Some of the compound radicals are obtainable in the free state ; 
others have yet to be proved capable of isolated existence.* 

Solid Potash. — Solution of potash evaporated to dryness in a sil- 
ver or clean iron vessel and the residue fused and poured into moulds 
constitutes Potassa, U. S. P. It often contains chlorides, detected 
by nitrate of silver ; sulphates, detected by a barium salt, as de- 
scribed subsequently in connection with hydrochloric and sulphuric 
acids ; and silica, which is precipitated on adding a strong solution 
to twice the quantity of alcohol. Liquor Potassa?, U. S. P., may be 
made by dissolving 56 parts of this hydrate in 944 of distilled water, 
or a corresponding quantity of potassa of any strength in water so as 
to make 1000 parts by weight. Potassa cum Calce, U. S. P., is a gray- 
ish-white powder, made by rubbing together equal weights of solid 
potash and quicklime. 

Sulphurated Potash. 

Second Synthetical Reaction. — Into a test-tube put a few grains 
of a mixture of dried carbonate of potassium with half its weight 
of sulphur. Heat the mixture gradually until it ceases to eifer- 
vesce. The resulting fused mass poured on a slab and quickly 
bottled is the Potassa Sulphurata, Sulphurated Potassa, U. S. P. 

3K 2 C(V + 4S 2 = 

Carbonate of Sulphur, 

potassium. 

As met with in pharmacy this salt is not a single definite chem- 
ical compound, but a mixture of several ; in short, its chemical 
character is well indicated by its vague name. When fresh, and if 
carefully prepared with the official proportions of dry ingredients, it 
is of the color of liver (whence the old name "liver of sulphur"), 
and consists, as shown by J. Watts, of the salts mentioned in the 
foregoing equation, together with a little undecomposed carbonate 
of potassium, with perhaps higher sulphides of potassium (K 2 S 4 
and K 2 S 5 ); but, rapidly absorbing oxygen from the air, it soon be- 
comes green and yellow, sulphite (K 2 S0 3 ) and sulphate of potassium 
(K. 2 S0 4 ) are formed, and ultimately a useless mass of dirty-white 
color results, consisting of sulphate and hyposulphite, with generally 
some carbonate of potassium and free sulphur. Moreover, if over- 
heated in manufacture, the hyposulphite 4(K 2 S a 3 ) is decomposed 
into sulphate o(K 2 SO.,) and sulphide (K 2 S 5 ) of potassium. Recently 
made, "about 50 per cent, should be soluble in rectified spirit." It 
is occasionally employed in the form of ointment. 

* Some modern authors term these roots radides, a word more use- 
fully expressive of little roots or rootlets. The word radicle is indeed 
thus used as a diminutive in botany. 



KAO, 


+ 2K& 


+ 


3C0 2 


Hyposulphite 


Sulphide of 




Carl ionic 


ot potassium. 


potassium. 




acid gas. 



68 



THE METALLIC RADICALS. 



" On triturating together 10 parts of Sulphurated Potassa and 
12.69 parts of crystallized sulphate of copper with 00 parts of 
water, and filtering, the filtrate should remain unaffected by hydro- 
sulphuric acid (presence of at least 56 per cent, of true sulphide of 
potassium)." U. S. P. 

The extremely, indeed most unusually, complicated nature of the 
reaction, will probably cause failure to any attempt by a student to 
draw out an equation or a diagram of the reaction without the aid 
of the printed equation given above. He may therefore content 
himself, in this case, by introducing into his note-book a diagram 
founded directly on the equation and on the numbers of molecules 
there stated. With this printed equation, and the details of con- 
struction of diagrams given in connection with the first synthetical 
reaction, he will be able to give a diagram of this second synthet- 
ical reaction without troubling his reasoning powers, while at the 
same time he will be familiarizing himself with the more mechanical 
portions of a diagram. 

In preparing large quantities of sulphurated potash, the test-tube 
is replaced by an earthenware vessel termed a crucible (from crux, 
a cross, for originally a cross was impressed upon the melting-pot 
as used by alchemists and goldsmiths : others derive the word from 
crux, an instrument of torture, the sense here being symbolical). 

Heating Crucibles. — Crucibles of a few ounces' capacity may be 
heated in an ordinary grate-fire. Larger ones require a stove with a 
good draught — that is. a furnace. Even the smaller ones are more 
conveniently and quickly heated in a furnace. Half-ounce or one- 
ounce experimental porcelain crucibles may be heated in a spirit- or 
gas-flame : the air-gas flame already described being generally the 
most suitable. 



Fig. 13. 



Fig. 14. 




Crucibles of various forms. 



Acetate of Potassium. 

Third S/jrifJntt'cal React ion. — Place ten or twenty or more 
grains of carbonate of potassium in a small dish, and saturate 
(satuTj full) with acetic acid ; that is, add acetic acid so long 
as effervescence is thereby produced ; the resulting liquid is a 
strong solution of acetate of potassium. 



ACETATE OF POTASSIUM. 63 

Evaporate most of the water in an open dish (see Figs. 15, 
16), stirring with a glass rod* to promote the evolution of 
vapor ; a white salt remains, which fuses on the further appli- 
cation of heat. This is the official Acetate of Potassium 
(Potassii Acetas, U. S. P.). If fused in the open vessel the 
acetate is liable to become slightly charred and discolored ; 
this is prevented by transferring the solid residue to a test- 
tube or Florence flask before finally fusing. It forms a white, 
deliquescent, foliaceous, satin-like mass, neutral to test-paper, 
and wholly soluble in spirit. A ten per cent, solution in water 
forms the " Solution of Acetate of Potash," B. P. 

K 2 C0 3 + 2HC 2 H S 2 = 2KC 2 H : A + H 2 + C0 2 

Carbonate of Acetic Acetate of Water. Carbonic 

potassium. acid. potassium. acid gas. 

Explanation of Formulae. — The formula for one molecule of 
acetic acid (the acetate of hydrogen) is HC 2 H 3 2 , and one of 
acetate of potassium, KC 2 H 3 2 . The grouping, C 2 H 3 2 , is cha- 
racteristic of all acetates ; it is univalent. 

Explanation of Process. — When two molecules of acetic acid 
(2HC 2 H 3 2 ) and one of carbonate of potassium (K 2 C0 3 ) react, two 
molecules of acetate of potassium (2KC 2 H 3 2 ) and one of carbonic 
acid (H 2 C0 3 ) are produced, the latter at once splitting up into water 
(1I 2 0) and carbonic acid gas (C0 2 ), as already shown in the equa- 
tion. 

Diagram of the Reaction. — The nature of the above operation is 
indicated by an equation; it (and succeeding reactions) should be 
expressed in the student's note-book as a diagram, and, if possible, 
without the aid of the equation. 

Note. — The reaction has a general as well as a special synthetical 
interest. It represents one of the commonest methods of forming 
salts, namely, the saturation of a carbonate by an acid or vice versa. 
Carbonates added to acetic acid yield acetates, to nitric acid nitrates, 
to sulphuric acid sulphates. Many illustrations of this general pro- 
cess occur in pharmacy. 

Evaporation of water from a liquid is best conducted in 
wide shallow vessels rather than in narrow deep ones, as the 
steam can thus quickly diffuse into the air and be rapidly con- 
veyed away; hence a small round-bottomed basin, heated as 
shown in Fig. 15, is far more suitable than a test-tube for such 
operations. On the manufacturing scale, iron, or iron lined 
with enamel or semi-porcelain, copper, tinned copper, or solid 



* Glass rod is usually purchased in the form of long sticks. The 
pieces may be cut to convenient lengths of from (! to 12 inches (vide 
p. 17), sharp ends being rounded off by holding the extremity in a 
name for a few minutes. 



70 



THE METALLIC RADICALS. 



tin pans are used. Up to 12 or 18 inches diameter, pans, 
basins, or dishes, made of Wedgwood ware or porcelain coin- 
position (Fig. 16), may be employed. Small dishes may be 



Fisr. 15. 



Fig. 16. 




Evaporation from small ami largo basins. 

supported by retort-stands (Fig. 15), larger by cylinders (Fig. 
16), to which the dish is, if less in diameter than the cylinder, 
adapted by such flat rings or diaphragms as are shown in the 

figure. 

Bicarbonate of Potassium. 
Fourth Synthetical Reaction. — Make a strong solution of 
carbonate of potassium by heating in a test-tube a mixture of 
several grains of the salt with rather less than an equal weight 
of water. Through the cooled solution pass carbonic acid gas 
slowly but continuously ; after a time a white crystalline pre- 
cipitate of Acid Carbonate or Bicarbonate of Potassium 
(KHC0 3 ), Potassii Bicarbonas, U. S. P., the Bicarbonate of 
Potash of old Pharmacopoeias, will be formed. 

KXU + H 2 + CO, = 2KIICO3 

Carbonate of Water. Carbonic Bicarbonate 

potassium. acid gas. of potassium. 

The carbonic acid gas necessary for this operation is to be pre- 
pared from marble, though it might be obtained from any carbonate. 
Thus the previous synthetical reaction could be made available for 
this purpose, the carl tonic acid gas evolved on the addition of the 
acetic acid to the carbonate of potassium being conducted into a 
strong solution of more carbonate of potassium by a glass tube bent 
and fitted as described when treating of oxygen gas. But motives 
of economy induct' the use of carbonate of calcium, the form known 
as marble being always employed. Economy and convenience also 
cause hydrochloric acid to be used in preference to acetic or any 
other. 



BICARBONATE OF POTASSIUM. 71 

Generate the carbonic acid gas by adding common hydro- 
chloric acid, diluted with twice its bulk of water, to a few 
fragments of marble contained in a test-tube or small flask, and 
conduct the gas into the solution of carbonate of potassium by 
. a glass tube bent to a convenient angle or angles, and fitted to 
the test-tube by a cork in the usual way. (See Fig. 10, though 
no heat is necessary.) The tube may be replenished with 
marble, or acid, or both, when the evolution of gas is becoming 
slow. In working on any larger quantity than a few grains of 
the carbonate, a wide delivery-tube should be employed, or the 
end of the narrow tube occasionally cleared from any bicar- 
bonate that may have been deposited in it. The more eco- 
nomical official arrangements of the apparatus employed in this 
process will be described under the corresponding sodium salt. 

Deposition of the Bicarbonate explained. — Bicarbonate of potas- 
sium is to a certain extent soluble in water ; but as it is less so than 
the carbonate of potassium, and as a saturated solution of the latter 
has been used, the precipitation of a part of the bicarbonate inevita- 
bly occurs. In other words, the quantity of water present is suffi- 
cient to keep the carbonate, but insufficient to retain the equivalent 
quantity of bicarbonate, in solution. 

Properties. — Prepared on the large scale, bicarbonate of potassium 
occurs in colorless, non-deliquescent, right rhombic prisms ; it has a 
saline, feebly alkaline, non-corrosive taste. Heated to redness, it 
loses 31 per cent of its weight, and is converted into carbonate 
(K 2 C0 3 ), water (H 2 0), and carbonic acid gas (C0 2 ). 

2KHC0 3 = K 2 C0 3 + H 2 + C0 2 

2 )200 2)138 2)18 2)44 

100 69 9 22 

31 

The foregoing equation and accompanying molecular weights (see 
page 54) show how bicarbonate of potassium, the molecular weight 
of which happens to be just 100, must lose 31 per cent, when com- 
pletely decomposed by heat. By ebullition of its solution it also is 
soon almost wholly changed to carbonate. 

Effervescing Solution of Potash. — A solution of 30 grains oi' 
bicarbonate of potassium in one pint of water, charged with 5 
times its bulk (often less) of carbonic acid gas by pressure, con- 
stitutes the official "potash-water/' the Liquor Potasses Eff'er- 
vescens, B. P. 

Notes on Nomenclature. — The prefix hi- in the name "bicarbonate 
of potassium" serves to recall the fact that to a given amount oi' 
potassium this salt contains twice as much carbonic radical as the 
carbonate. The salt is really a "carbonate of potassium and hydro 
gen" (KHCOjj) ; it h "ntermediate between carbonate of potassium 



72 THE METALLIC KADICALS. 

(K 2 C0 3 ) and carbonate of hydrogen, or true carbonic acid (H 2 C0 3 ) ; 
it is " acid carbonate of potassium " or " hydric potassium carbonate." 
Hence in constitution it is an acid salt, although not acid to the 
taste. 

Salts whose specific names end in the syllable "ate" (carbonate, 
sulphate, etc.) are in general conventionally so termed when they 
contain an acidulous radical, or the characteristic elements of an 
acid whose name ends in " ic" and from which acid they hare been 
or may be formed. Thus the syllable " ate," in the words sulphate, 
nitrate, acetate, carbonate, etc., indicates that the respective salts 
contain a radical whose name ended in ic, the previous syllables, 
sulph-, nitr-, acet-, carbon-, indicating what that radical was — the 
sulphuric, nitric, acetic, or carbonic. Occasionally a letter or syl- 
lable is dropped from or added to a word to render the name more 
euphonious 5 thus the sulphuric radical forms sulphates, not sul- 
phurates. 

Citrate of Potassium. 

Fifth Synthetical Reaction. — Dissolve a few grains or more 
of bicarbonate (or 8 parts) of potassium in water, and add (6 
parts of) citric acid (H 3 C 6 H 5 7 ) until it no longer causes effer- 
vescence. The resulting liquid is a solution of citrate of potas- 
sium (K 3 C 6 H 5 7 ) {Liquor Potasm Citratw, U. S. P., sp. gr. 1.059). 
Evaporated to dryness, in an open dish, a pulverulent or granular 
residue is obtained, which is the official Potassii Oitras, U. S. P., 
a white deliquescent powder. 

3KHC0 3 + H 3 C 6 H 5 7 = K,C 6 H 5 7 + 3H 2 + 3C0 2 

Carbonate of Citric acid. Citrate of Water. Carbonic 

potassium. potassium. acid gas. 

Citrates. — The citric radical or group of elements, which with 
three atoms of hydrogen forms a molecule of citric acid, and with 
three of potassium citrate of potassium, is a trivalent grouping : 
hence the three atoms of potassium in a molecule of the citrate. 
The full chemistry of citric acid and other citrates will be subse- 
quently described. 

Nitrate of potassium (KN0 3 ) (Potassii Nitras, U. S. P.) and Sul- 
pliate of potassium (K 2 S0 4 ) (Potassii Sulphas, U. S. P.) could ob- 
viously also be made by saturating nitric acid (HN0 3 ), and sul- 
phuric acid (H 2 S0 4 ), respectively, by carbonate of potassium. Prac- 
tically, they are not made in that way — the nitrate occurring, as 
already stated, in nature, and the sulphate as a by-product in many 
operations. Both salts will be hereafter alluded to in connection 
with nitric acid. 

Tartrate of Potassium. 
Sixth Synthetical Reaction. — Place a few grains of car- 
bonate of potassium in a test-tube with a little water, heat 
to the boiling-point, and then add acid tartrate of potassium 
(KHC 4 H 4 6 or KHT) till there is no more effervescence ; a 



IODIDE OF POTASSIUM. 73 

solution of neutral tartrate of potassium (K 2 T) results, the 
Potassii Tartras of the United States Pharmacopoeia, the old 
ic Soluble Tartar." Crystals (4- or 6-sided prisms) may be 
obtained on concentrating the solution by evaporation and 
setting- the hot liquid aside. Larger quantities are made in 
the same way, 20 of acid tartrate and 9 of carbonate (with 50 
of water) being about the proportions necessary for neutrality. 

2KHC 4 H 4 6 + K 2 C0 3 = 2K 2 C 4 H 4 6 + H 2 + CO, 

Acid tartrate of Carbonate of Neutral tartrate Water. Carbonic 

potassium. potassium. of potassium. acid gas. 

Tartrates. — C 4 H 4 6 are the elements characteristic of all tar- 
trates ; they form a bivalent grouping ; hence the formula of the 
hydrogen tartrate, or tartaric acid, is H 2 C 4 H 4 6 5 that of the potas- 
sium tartrate K 2 C 4 H 4 6 ; of the intermediate salt, the acid potas- 
sium tartrate (cream of tartar), KHC 4 H 4 6 . If the acid tartrate of 
one metal and the carbonate of another react, a neutral dimetallic 
tartrate results, as seen in Rochelle salt (KNaC 4 H 4 6 , 4H 2 0), the 
Soda Tartarata of the British Pharmacopoeia {Potassii et Sodii 
Tartras, U. S. P.). 

Acid salts (e. g. KH0 4 H 4 O 6 ), that is, salts intermediate in compo- 
sition between a normal or neutral salt (e. g. K 2 C 4 H 4 6 ) and an acid 
(e. g. H 2 C 4 H 4 6 ), will frequently be met with. All acidulous radi- 
cals, except those which are univalent, may be concerned in the for- 
mation of such acid salts. 

Iodide of Potassium. 

Seventh Synthetical Reaction. — Into a solution of potash, heat- 
ed in a test-tube, or flask, or in an evaporating basin, according 
to quantity, stir a small quantity of solid iodine. The deep color 
of ihe iodine disappears entirely. This is due to the formation 
of the colorless salts, iodide of potassium (KI) and iodate of 
potassium (KT0 3 ), which remain dissolved in the liquid. Con- 
tinue the add. Lion of iodine so long as its color, after a few 
minutes' warming and stirring, disappears. When the whole 
of the potash in the solution of potash has been converted into 
the salts mentioned, the slight excess of iodine remaining in 
the liquid will color it, and thus show that this stage of the 
operation is completed. 

6KHO + 3I 2 = 5KI + KI0 8 + 3H.0 

Hydrate of Iodine. Iodide of Iodate of Water, 

potassium. potassium. potassium. 

Separation of the Iodide from the Iodate. — Evaporate the 
solution to dryness. If each salt were required, the resulting 
solid mixture might be digested in spirit o\' wine, which dis- 
solves the iodide, but not the iodate. But the iodide only is 
used in medicine. Mix the residue, therefore (reserving a 



74 THE METALLIC RADICALS. 

grain or two for a subsequent experiment), with about a twelfth 
of its weight of charcoal, and gently heat in a test-tube or 
crucible until slight deflagration ensues* 

The crucible may be held in a spirit or air-gas flame, or 
other fire, by tongs. (Scissors-shaped and other " crucible- 
tongs " are sold by all makers of apparatus.) Under these 
circumstances the iodide remains unaffected ; but the iodate 
loses all its oxygen, and is thus also reduced to the state of 
iodide. 



2KI0 3 


+ 


3P 

Olv 2 


= 2KI 


_|_ 


6CO 


Iodate of 




Carbon. 


Iodide of 




Carbonic 


potassium. 






potassium. 




oxide. 



Treat the mass with a little water, and filter to separate ex* 
cess of charcoal ; a solution of pure iodide of potassium results. 
(Potassii Iodidum, U. S. P.) The latter may be used as a re- 
agent or it may be evaporated to a small bulk and set aside to 
crystallize. 

Propwties. — Iodide of potassium crystallizes in small cubical crys- 
tals, very soluble in water, less so in spirit. One part in twenty of 
water forms " Solution of Iodide of Potassium," U. S. P. Exposed 
to air and sunlight, pure iodide of potassium becomes slightly brown 
owing to the liberation of iodine. Under these circumstances a little 
carbonate of potassium is produced by action of the atmospheric 
carbonic acid and a little hydriodic acid (HI) is set free, and the 
latter, attacked by oxygen, yields a trace of water and of free iodine. 
The ozone in the air (see " Ozone" in Index) may also contribute to 
the liberation of iodine from such compounds as iodide of potassium. 

The addition of charcoal in the above process is simply to facili- 
tate the removal of the oxygen of the iodate of potassium. Iodate 
of potassium (KI0 3 ) is analogous in constitution, and in composition, 
so far as the atoms of oxygen are concerned, to chlorate of potassium 
(KCIO3), which has already been stated to be more useful than any 
other salt for the actual preparation of oxygen gas itself. Hence the 
removal of the ox3^gen of the iodate might be accomplished by heat- 
ing the residue without charcoal. In that case the liberated oxygen 
would be detected on inserting the incandescent extremity of a strip 
of wood into the mouth of the test-tube in which the mixture of 
iodide and iodate had been heated. The charcoal, however, burns 

! * If, in the operation of heating iodate of potassium with charcoal, 
excess of the latter be employed, slight incandescence rather than 
deflagration occurs; if the charcoal be largely in excess, the reduc- 
tion of the iodate to iodide of potassium is effected without visible 
deflagration or even incandescence. 

Deflagration means violent burning, from flagratus, burnt (flagro, I 
burn), and de, a prefix augmenting the sense of the word to which it 
may he attached. Paper thrown into a fire simply burns, nitre defla- 
grates. £>e-tonate (detono) is a precisely similar word, meaning to ex- 
plode with violent noise. 



IODIDE OF POTASSIUM. 75 

out the oxygen more quickly, and thus economizes both heat and 
time. 

Note. — The formula of iodide of potassium (KI) shows that the 
salt contains potassium and iodine in atomic proportions. A refer- 
ence to the table of atomic weights at the end of the volume, and a 
rule-of-three sum, would therefore show what weight of salt is pro- 
ducible from any given weight of iodine. 

Detection of Iodate in Iodide of Potassium. — Iodate of po- 
tassium remaining as an impurity in iodide of potassium may 
be detected by adding to a solution of the latter salt some 
weak acid (say tartaric), shaking, and then adding mucilage of 
starch ; blue " iodide of starch " is formed if a trace of iodate 
be present, not otherwise. By the reaction of the added acid 
and the iodate of potassium, iodic acid (HI0 3 ) is produced, 
and by reaction of the added acid and the iodide of potassium, 
hydriodic acid (HI) is produced ; neither of these two acids 
alone attacks starch, but by reaction on each other they give 
rise to free iodine, which then forms the blue color. This ex- 
periment should be tried on a sample of pure iodide of potas- 
sium and on a grain or two of the impure iodide reserved from 
the previous experiment. Iodide of potassium containing iodate 
would, obviously, yield free iodine, which is excessively corrosive, 
on the salt coming into contact with the acids of the stomach. 
HI0 3 + 5HI = 2H,0 + 3I 2 . 

Note on Nomenclature. — The syllable ide attached to the syllable 
iod, in the name " iodide of potassium," indicates that the element 
iodine is combined with the potassium. An iodate, as already ex- 
plained, is a salt containing the characteristic elements of iodic acid 
and of all iodic compounds. Inorganic salts one of whose names 
ends in ide are those which are, or may be, formed from elements. 
The names of salts which are, or may be, formed from compounds 
include other syllables, ate being one (see page 72). The only other 
syllable is ite, which is included in the names of salts which are, or 
may be, formed from acids and radicals whose names end in ous: 
thus hyposulphite of sodium, etc. To recapitulate : an inorganic 
salt whose name ends in ate contains a compound acidulous radical 
whose name ends in ic ; a salt whose name ends in ite contains a 
compound acidulous radical whose name ends in ous ; an inorganic 
salt whose name ends in ide contains an element for its acidulous 
radical. Thus sulphide relates to sulphur, sulphite to the sulphur- 
ous radical, sulphate to the sulphuric radical, aud so on with other 
inorganic "ides," " ites," or " ates." 

Bromide of Potassium (jPotassii Bromidum, V. S. P.) — This salt 
is identical in constitution with iodide of potassium, and may be 
made in exactly the same way, bromine being substituted for iodine. 
The formula of bromic acid is HBrO s . It will be noticed that the 
following equations are similar in character to those showing the 
preparation of iodide of potassium : — 



76 THE METALLIC RADICALS. 

6KII0 + 3Br 2 = 5KBr + KBr0 3 + 3H 2 

Hydrate of Bromine. Bromide of Bromate of Water, 

potassium. potassium. potassium. 

2KBr0 3 + 3C 2 = 2KBr + 6CO 

Bromate of Carbon. Bromide of Carbonic 

potassium. potassium. oxide. 

Bromide of potassium may also be made by decomposing solution 
of bromide of iron (FeBr 2 ) by solution of pure carbonate of potas- 
sium (K 2 C0 3 ), evaporating and crystallizing. 

Manganates of Potassium. 

Eighth Synthetical Reaction. — Place a fragment of solid 
caustic potash (KHO), with about the same quantity of chlo- 
rate of potassium (KC10 3 ), and of black oxide of manganese 
(Mn0 2 ) on a piece of platinum foil.* Hold the foil by a small 
pair of forceps or tongs in the flame of a blowpipe for a few 
minutes until the fused mixture has become dark green — ap- 
parently black. This color is that of manganate of potassium 
(K 2 Mn0 4 ). 

6KHO + KCIO3 + 3Mn0 2 = 3K 2 Mn0 4 + KC1 + 3H 2 

Hydrate of Chlorate of Black oxide of Mangauate of Chloride of Water, 
potassium. potassium. manganese. potassium. potassium. 

Ninth Synthetical Reaction. — Permanganate of Potassium 
(K 2 Mn 2 8 ) (Potassii Permanga-nas, U. S. P.), which is purple, 
is obtained, or rather a solution of it, on placing the foil and 
its adherent mass in water, and boiling for a short time. 

3K 2 Mn0 4 + 2H 2 - K 2 Mn 2 8 + 4KHO + Mn0 2 

Manganate of Water. Permanganate Hydrate of Black oxide 

potassium. of potassium. potassium. of manganese. 

On the large scale, the potash set free in the reaction is neutral- 
ized by sulphuric or, better, carbonic acid, and the solution evap- 
orated to the crystallizing point. Further details will be given in 
connection with manganese. 

Solutions of manganate or permanganate of potassium and of 
sodium so readily yield their oxygen "to organic matter, that they 
are used on the large scale as disinfectants, under the name of 
" Condy's Disinfecting Fluids." 

Synthetical Reactions bringing under consideration the remaining 
official compounds (namely," bichromate, arsenite, chlorate, cyan- 

* The foil may be 1 inch broad by 2 inches long. No ordinary flame 
will melt the platinum; fused caustic alkalies only slowlv corrode it, and 
very few other chemical substances affect it at all ; hence the same piece 
may be used in experimenting over and over again. Most metals form 
a fusible alloy with platinum, and phosphorus rapidly attacks it, hence 
such substances, as well as mixtures likely to yield them, should be 
heated in a small porcelain crucible. 



MANGANATES OF POTASSIUM. 77 

ide, ferrocyanide, and ferridcyanide of potassium) are deferred at 
present. 

(b) Reactions having Analytical Interest (Tests). 

Note. — These are reactions utilized in searching for small quanti- 
ties of a substance (in the present instance of potassium) in a solu- 
tion. They are best performed in test-tubes or other small vessels. 
Each reaction should be expressed, in the form of an equation or 
diagram, in the student's note-book. All previous or future equa- 
tions given in this volume should be transferred to the note-book in 
the form of diagrams, constructed as described on pages 63 and 64, 
unless the student can with ease construct the equations without the 
aid of the manual. 

First Analytical Reaction* — To a solution of any salt of 
potassium (cnloride,f for example) add a few drops of hydro- 
chloric acid and of a solution of perchloride of platinum 
(PtCl 4 ), and stir the mixture with a glass rod ; a yellow gran- 
ular or slightly crystalline precipitate J slowly forms. (The . 
precipitate is the double chloride of platinum and potassium, 
and its composition is expressed by the formula PtCl 4 2KCl.) 

Memoranda.^ — When the precipitate is long in forming, it is some- 

* As already indicated, chemical reactions are scarcely analytical 
or synthetical in themselves, but, rather, performed with an analytical 
or synthetical object. Indeed, not unfrequently one and the same re- 
action is both a synthetical and an analytical reaction. Thus this 
first, so-called, "analytical reaction" is a synthetical reaction if per- 
formed with the object of preparing a specimen of the double chloride 
of platinum and potassium. It is an analytical reaction, or, rather, 
has analytical interest, if performed with the object of demonstrating 
the presence of potassium. Chemical reactions in themselves are 
operations, not so much of analysis (resolution) or synthesis (combina- 
tion) or of analysis and synthesis conjoined, as of what has sometimes 
times been termed metathesis (transposition). Molecules are not torn 
to atoms in an operation performed with an analytical object, nor are 
the atoms put together or set together in an operation (perhaps the 
same operation) performed with a synthetical object: but in both 
operations the atoms of the molecules undergo metathesis, that is, 
exchange places, or are transposed. In short, chemists use the words 
"analytical" and "synthetical" in a conventional rather than a 
strictly etymological sense. 

f A few fragments of carbonate of potassium, two or three drops of 
hydrochloric acid, and a small quantity of water, give a solution oi 
chloride of potassium at once, K 2 C0 3 + 2HC1 — 2KC1 + H.,0 CO a , 

% By precipitation (from prmcipito, to throw down suddenly) is simply 
meant the formation of particles of solid in a liquid, no matter whether 
the solid, the precipitate, subsides or floats. 

\ Experiments with such expensive reagents as perchloride o( plat- 
inum are economically performed with watch-glasses, drops of the 
liquid being operated on. 



78 THE METALLIC RADICALS. 

times of an orange-yellow tint. If iodide of potassium happen to 
be the potassium salt under examination, some iodide of platinum 
(Ptl 4 ) will also be formed, giving a red color to the solution, and a 
larger quantity of the precipitant (that is, the precipitating agent) 
will be required. 

Precaution. — Only chloride of potassium forms this characteristic 
compound : hence, if the potassium salt in the solution is known not 
to be a chloride, or if its composition is unknown, a few drops of 
hydrochloric acid must be added, otherwise some of the perchloride 
of platinum will be utilized for its chlorine only, the platinum being 
wasted. Thus, if nitrate of potassium (KX0 3 ) be present, a few 
drops of hydrochloric acid enable the potassium to assume the form 
of chloride when the perchloride of platinum is added, nitric acid 
(HX0 3 ) being set free. 

Explanation. — The precipitate is, practically, insoluble in water. 
It is for this reason that a very small quantity of any soluble potas- 
sium salt (or, rather, of the potassium in that salt) is thrown out of 
solution by perchloride of platinum. 

Note on Nomenclature. — When distinct molecules of salts unite 
and form a single crystalline compound, the product is termed a 
double salt. The double chloride of potassium and platinum is 
such a body. 

Acid Tartrate of Potassium. 

Second Analytical Reaction. — To any solution of any salt 
of potassium add excess of strong solution of tartaric acid 
(H 2 C 4 H 4 6 ), and shake or well stir the mixture ; a white gran- 
ular precipitate of acid tartrate of potassium (KHC 4 H 4 6 ) 
will be formed. 

Note. — By " excess " of any test liquid (such as the " solution of 
tartaric acid '' just mentioned) is meant such a quantity as is probably 
rather more than sufficient to convert the whole weight of the com- 
pound attacked into the compound produced. Thus, in the present 
case enough acid must be added to convert the whole of the potas- 
sium salt operated on into acid tartrate of potassium. AVhat the 
weight of salt operated on was must be mentally estimated, roughly, 
by the operator. It is not necessary in analyzing to know the exact 
weights of salts employed. The analyst must use his judgment, 
founded on his knowledge of the reaction (as shown by an equation) 
and of the molecular weights of the substances employed in the 
reaction as well as by the rough estimate of the amount of material 
on which he is experimenting. 

Limit* of the Test. — Acid tartrate of potassium is soluble in about 
180 parts of cold and in 6 parts of boiling water. Hence, in apply- 
ing the tartaric test for potassium, the solutions must not be hot. 
Even if cold, no precipitate will be obtained if the solutions are 
very dilute. This test, therefore, is of far less value than that first 
mentioned. The acid tartrate of potassium is less soluble in diluted 
alcohol than in water ; so that the addition of spirit of wine renders 
the reaction somewhat more delicate. 



ACID TARTRATE OF POTASSIUM. 79 

Cream of Tartar. — The precipitate is the Bitartrate or Acid Tar- 
trate of Potassiwn (Potassii Bitartras, U. S. P.), though the official 
preparation is not formed in the above manner ; on the contrary, 
the acid is derived from the salt, which, often mixed with some tar- 
trate of calcium, occurs naturally in the juice of many plants. 

Memorandum. — When the tartaric acid is added to the salt of 
potassium, and the acid tartrate formed, the acid whose chief ele- 
ments were previously with the potassium is set free 5 and in such 
acid solutions the acid tartrate is somewhat soluble. To prevent 
loss on this account, acid tartrate of sodium, or Bitartrate of So- 
dium, U. S. P., NaHC 4 H 4 6 , H 2 0, a salt tolerably soluble in water, 
may be used as a test instead of tartaric acid (Plunkett). The 
sodium, uniting with the acidulous radical, thus gives a neutral 
instead of an acid solution. But this advantage is of less import- 
ance from the fact that more water is introduced by the saturated 
solution of acid tartrate of sodium than by a saturated solution of 
tartaric acid. 

Third Analytical Reaction. — The flame-test. Dip the looped 
end of a platinum wire into a solution containing a potassium 
salt, and introduce the loop into the lower part of a spirit- 
flame, the flame of a mixture of gas and air, a blowpipe flame, 
or other slightly colored flame. A light violet or lavender tint 
will be communicated to the flame, an effect highly character- 
istic of salts of potassium. 

Fourth Analytical Fact. — Salts of potassium are not vola- 
tile. Place a fragment of carbonate, nitrate, or any other po- 
tassium salt, on a piece of platinum foil, and heat the latter 
in the flame of a lamp ; the salt may fuse to a transparent 
liquid and flow freely over the foil, water also if present will 
escape as steam, and black carbon be set free if the salt hap- 
pen to be a tartrate, citrate, etc. ; but the potassium compound 
itself will not be vaporized. This is a valuable negative prop- 
erty, as will be evident when the analytical reactions of ammo- 
nium come under notice. 



QUESTIONS AND EXERCISES. 

70. Name the sources of Potassium. 

71. Give the source, formula, and characters of Carbonate of 
Potassium. 

72. Distinguish between synthetical and analytical reactions. 

73. How is the official Liquor Potassce prepared? 

74. What is the systematic name of Caustic Potash? 

75. State the chemical formula of Caustic Potash. 

7G. Construct an equation or diagram expressive of the reaction 
between Carbonate of Potassium and slaked Lime. 
77. Define a hydrate. 



80 THE METALLIC RADICALS. 

78. What group of atoms is characteristic of all carbonates ? 

79. Define the term radical. 

80. How is " Sulphurated Potash " made, and of what salts is it a 
mixture ? 

81. What is the formula of the acetic radical — the radical of all 
acetates ? 

82. Draw a diagram showing the formation of Acetate of Potas- 
sium. 

83. Give a general process for the conversion of carbonates into 
other salts. 

84. What is the difference between Carbonate and Bicarbonate of 
Potassium ? How is the latter prepared ? 

85. What is the relation between salts whose specific names end 
in the syllable " ate," and acids ending in u ic"? 

86. Draw out diagrams or equations descriptive of the formation 
of Tartrate of Potassium from the Acid Tartrate, and Citrate from 
the Carbonate of Potassium, 

87. Distinguish between a normal and an acid salt. 

88. How is Iodide of Potassium made? Illustrate the process 
either by diagrams or equations. 

89. Describe the appearance and chemical properties of Iodide of 
Potassium. 

90. Work out a sum showing how much Iodide of Potassium is 
producible from 1000 grains of Iodine? Ans. 1307 grains. 

91. Give a method for the detection of Iodate in Iodide of Potas- 
sium. Explain the reaction. 

92. Has the syllable u ide" any general significance in chemical 
nomenclature ? 

93. What are the differences between sulphides, sulphites, and 
sulphates ? 

94. Mention the chemical relations of Bromide to Iodide of Potas- 
sium. 

95. Describe the formation of Permanganate of Potassium, giving 
equations or diagrams. 

96. How do manganate and permanganate of potassium act as 
disinfectants ? 

97. Enumerate the tests for potassium, explaining by diagrams or 
equations the various reactions which occur. 



SODIUM. 

Symbol Na. Atomic weight 23. 
Formula Na r Probable molecular weight 46. 
Memoranda. — Most of the sodium salts met with in Pharmacy 
are obtained directly from carbonate of sodium, which is now manu- 
factured on an enormous scale from chloride of sodium (common 
salt, sea-salt, bay-salt, or rock-salt), the natural source of the so- 
dium salts. When pure, salt (Sodii Chloridum, U. S. P.) occurs " in 
small white crystalline grains, or transparent cubic crystals, free 
from moisture ;" the best varieties commonly contain a little chlo- 



SODIUM. 81 

ride of magnesium and sometimes other impurities. Besides the direct 
and indirect use of carbonate of sodium, or carbonate of- soda, as it is 
commonly called in medicine, it is largely used for household cleansing 
purposes under the name of " soda," and in the manufacture of soap. 
Nitrate of sodium also occurs in nature, but is valuable for its nitric 
constituents rather than its sodium. Sodium is a constituent of about 
forty chemical or Galenical preparations of the Pharmacopoeias. 

Sodium is prepared by a process similar to that for potassium, but 
with less difficulty. Castner obtains it comparatively cheaply by dis- 
tillation from a mixture of soda, carbon, and iron contained in steel 
vessels. It has a bright metallic lustre when freshly cut, but rapidly 
absorbs oxygen and moisture and carbonic acid gas from the air, and 
thus becomes coated with carbonate of sodium. It displaces hydrogen 
from water, yielding a solution of hydrate of sodium, but unless the 
sodium is confined to one spot by placing it on a small floating piece 
of filter-paper, the action is not sufficiently intense to cause ignition 
of the escaping hydrogen. When the latter does ignite, it burns with 
a yellow flame, due to the presence of a little vapor of sodium. It 
crystallizes in octahedra. Its atom is univalent, Na / . 

Na 2 + 2II 2 = H 2 + 2NaHO. 

Sodium. Water. Hydrogen. Hydrate of sodium. 

It similarly attacks alcohol, yielding ethylate of sodium (see In- 
dex). It may be kept beneath the surface of a liquid containing 
neither moisture nor oxygen in any form (mineral naphtha). 

Keactjons having (a) Synthetical and (fe) Analytical 
Interest. 

(a) Reactions having Synthetical Interest. 

Hydrate of Sodium. Caustic Soda. 
First Synthetical Reaction. — The formation of solution of 
hydrate of sodium or caustic soda, NaHO (Liquor Sodse, U. 
S. P.). This operation resembles that of making solution of 
potash already described, and its strength is the same, " about 
5 per cent. ;" sp. gr. about 1.059. 



Na 2 C0 3 


+ 


Ca2HO = 


= 2NaHO 


+ CaCO, 


Carbonate 




Hydrate of 


Hydrate of 


Carbonate 


of sodium. 




calcium. 


sodium. 


of calcium. 



The practical student should refer to the remarks made concerning 
solution of potash, applying them to solution of soda. 1 f solution of 
soda be evaporated to dryness, and the residue fused and poured into 
moulds, solid hydrate of sodium (Soda, U. S. P.) is obtained. Com- 
mon and cheap caustic soda is now largely employed in various man- 
ufactures. This variety is a by-product in the preparation of carbon- 
ate of sodium, but, though highly useful as a chemical agent, is too 
impure for use in medicine. The United States Pharmacopoeia rec- 
ognizes Liquor Soda) made from solid caustic soda 56 parts, and dis- 



82 THE METALLIC RADICAL?. 

tilled -water 944 parts ; or from caustic soda of any other strength if 
only an equivalent amount be used. 

Second Synthetical Reaction. — The reaction of sulphur and 
carbonate of sodium at a high temperature resembles that of 
sulphur and carbonate of potassium: but. as the product is not 
used in medicine, the experiment may be omitted. It is men- 
tioned here to draw attention to the close resemblance of the 
potassium salts to those of sodium. 

Acetate of Sodium. 
Third Synthetical Reaction. — Add the powder or fragments 
of carbonate of sodium f XaX'CV; to some strong acetic acid in 
a test-tube or evaporating-basin as long as effervescence occurs, 
and then evaporate some of the water.* When the solution 
is cold, crystals of Acetate of Sodium XaC,H 3 2 .3H,0) (Sodii 
Acetas, U. S. P.) will be deposited. A ten per cent, solution 
in distilled water forms the " Solution of Acetate of Sodium." 
B. P. 

Acetate of sodium effloresces in dry air. and loses all its 
water of crystallization when gently heated. It supports a 
temperature of 270° or 280° F. without decomposition, but 
above 30u° soon chars. 

Xa.CO, - 2HC 8 HA = 2XaC\HA - H 2 - C0 2 

Carbonate Acetic acid. Acetate of Water. Carbonic 

of sodium. aodimn. acid gas. 

Bicarbonate of Sodium. 
Fourth Synthetical Reaction. — The action of carbonic acid 
(H 8 CO a ) or carbonic acid gas C< ». and water (H 2 0), on car- 
bonate of sodium (XaX'Ojj. This resembles that of carbonic 
acid on carbonate of potassium, but is applied in a different 
manner. The result is bicarbonate of sodium (NaHC0 3 j 
{Soda. JSicarbonas Venalis, V. S. P.). 



Na CO - 


- H..0 


- CO, = 


: 2NaHCO a 


Carbonate 


Water. 


Carbonic 


Bicarbonate of 






. 


sodium. 



Process. — Heat crystals of carbonate of sodium in a porce- 
lain crucible until no more steam escapes. Rub the product, 
in a mortar, with two-thirds its weight of more of the crystals 
and place the powder in a test-tube or small bottle into which 
carbonic acid gas may be conveyed by a tube passing through 

* The ''water" alluded to occurs in the acid, which, though com- 
monly termed "acetic"' acid, is really a solution of that acid in water. 




BICARBONATE OF SODIUM. 83 

a cork and terminating at the bottom of the vessel. To gene- 
rate the carbonic acid gas fill a test-tube having a small hole 
in the bottom (or a similar piece of glass tubing, of which one 
end is plugged by a grooved cork) with fragments of marble, 
insert a cork and delivery-tube, and connect the latter with the 
similar tube of the vessel con- 
taining the carbonate of so- Fig 17. 
dium by a piece of India- 
rubber tubing. Now plunge 
the tube of marble into a 
test-glass, or other vessel, 
containing a mixture of one 
part hydrochloric acid and 
two parts water, and loosen 
the cork of the carbonate-of- 
sodium tube until carbonic 

acid gas, generated in the Preparation of bicarbonate of sodium. 

marble tube, may be con- 
sidered to fill the whole arrangement ; then replace the cork 
tightly and set the apparatus aside. As the gas is absorbed by 
the carbonate of sodium, hydrochloric acid rises into the marble 
tube, and generates fresh gas, which, in its turn, drives back 
the acid liquid, and thus prevents the production of any more 
gas until further absorption has occurred. When the salt is 
wholly "converted into bicarbonate (NaHC0 3 ), it will be found 
to have become damp through the liberation of water from the 
crystallized carbonate (Na 2 CO 3 ,10H 2 O). (It would be inconve- 
niently moist, even semi-fluid, if a part of the carbonate had 
not previously been rendered anhydrous.) The Sorfu Bicar- 
bonas, U. S. P., is the commercial bicarbonate purified from 
any carbonate or traces of other salts by introducing it into a 
percolator and passing water through it till the washings cease 
to precipitate a solution of sulphate of magnesium, when the 
bicarbonate of sodium is removed from the percolator and 
dried on bibulous paper in a warm place. 

The carbonate of sodium may be placed, not in a test-tube or bottle, 
but in a vertical tube the bottom of which is loosely closed by a grooved 
cork. Any water of crystallization that is set free then runs oft' (into 
a basin or cup beneath), and takes with it any impurities (chlorides or 
sulphates, etc.) that may have been present in the original salt. 

Bicarbonate of sodium is also now largely prepared by adding 
bicarbonate of ammonium to a strong solution of common salt ; 
bicarbonate of sodium is precipitated. 



NHJieO, 4 NaCl = 


NaHC0 8 


f \ii t n 


Bicarbonate of Chloride of 


Bicarbonate 


Chloride* 


ammonium. sodium. 


Of sodium. 





84 THE METALLIC RADICALS. 

The resulting chloride of ammonium is reconverted into carbonate 
(p. 91)-, the latter, more fully carbonated, again used for producing 
bicarbonate of sodium. Indeed, carbonate of sodium (Sodii Car- 
bonds, U. S. P.) is commercially made by heating the bicarbonate thus 
obtained, the carbonic acid then liberated serving for the convert- 
ing of the carbonate of ammonium into bicarbonate of ammonium. 
2XaIIC0 3 = Na 2 C0 3 -f II 2 -f C0 2 

Bicarbonate Carbonate Water. Carbonic 

of sodium. of sodium. acid gas. 

A crystal of carbonate of sodium is carbonate of sodium plus 
water (Sodii Carbonas, U. S. P. ; see " Carbonates") ; on heating it, 
more or less of the water is evolved, and anhydrous carbonate of 
sodium is partially or wholly produced (Sodii Carbonas Exsiccatus, 
U. S. P.). 

Na,CO 3 ,10H 2 O — 10H 2 O = Na 2 C0 3 

Crystallized carbonate Water Dried carbonate 

of sodium (286). (180). of sodium (106). 

According to the United States Pharmacopoeia dried carbonate of 
sodium is to be prepared by exposing crystals of carbonate of so- 
dium to warm air for several days to effloresce, and then to a tem- 
perature of about 45° C. until half the original weight is obtained. 
286 parts would thus become 143, and the latter would thus still 
retain 37 parts of water. In other words, the dried carbonate con- 
tains 72.6 per cent, of anhydrous carbonate and 27.4 per cent, of 
water. The crystals contain, obviously, a little more than 37 per 
cent, of anhydrous carbonate and nearly 63 per cent, of water. The 
student should verify all these figures. 

Note on Nomenclature. — Anhydrous bodies (from a, a, and vdup, 
hudor, i. c. without water) are compounds from which water has 
been taken, but whose essential chemical properties arc unaltered. 
Salts containing water are hydrous bodies ; of these the larger por- 
tion are crystalline, and their water is then termed water of crystal- 
lization. Non-crystalline hydrous compounds were formerly spoken 
of as hydrated substances ; hydrates are, however, a distinct class 
of bodies, salts derived from water by one-half of its hydrogen 
becoming displaced by an equivalent quantity of another radical. 
Anhydrides form still another distinct class of chemical substances ; 
they are derived from acids ; in short, they are acids from which, 
noU exactly water as water, but the elements of water have been 
removed, the essential chemical (acid) properties being thereby 
greatly altered. (For illustrations, see Index, " Anhydrides.") 

Water of Crystallization. — The water in crystallized carbonate 
of sodium is in the solid condition, and, like ice and other fusible 
substances, requires heat for its liquefaction. Many salts (freezing- 
mixtures), when dissolved in water, give a very cold solution. This 
is because they and their solid water, if they have any, are then, 
absorbing some heat from surrounding media, converted into liquids! 
Take away from water some of its heat, the result is ice. Give to ice 
(at 32? F.J more heat than it contains already, the result is water 
(still at 32° F.). (Heat thus taken into a substance without increas- 
ing its temperature is said to become latent — from latens, hiding: it 



BICARBONATE OF SODIUM. 85 

is no longer discoverable by the sense of touch or the thermometer. 
The term latent gives a somewhat incorrect idea, however, of the 
process ; for our knowledge of the extent and readiness with which 
one form of force is convertible into another renders highly probable 
the assumption that heat is in these cases converted into motion, the 
latter enabling the molecules of a solid to take up the new positions 
demanded by their liquid condition.) The only apparent difference 
between ice and the water in such crystals as carbonate of sodium is 
that ice is solid water in the free, and water of crystallization solid 
water in the combined state. The former can only exist at and below 
32° F. 5 the latter may exist at ordinary temperatures. Many salts, 
however, which unite with little or even no water of crystallization 
at common temperatures, take up much, according to Guthrie, at very 
low temperatures, and such salts he calls cryohydrates (xP v °Si kruos, 
icy cold, frost). On the other hand, all water of crystallization is 
dispelled at high temperatures. In chemical formulae, the symbols 
representing water are. usually separated by a comma from those 
representing salts. The crystals of acetate of sodium (of the third 
reaction) contain water in this loose state of combination — water of 
crystallization (NaC 2 H 3 2 ,3H 2 0). It is just possible, however, that 
this so-called " water of crystallization" is in a more intimate state 
of combination than is indicated by such a formula as that ust given. 

" Soda-water" — A solution of bicarbonate of sodium in water 
charged with carbonic acid gas under pressure constitutes the offi- 
cial Liquor Sodce Uffervescens, B. P., and, like the "potash-water" 
of the shops, is a true medicine, an antacid. Ordinary "soda-water," 
however, is in many cases simply a solution of carbonic acid gas in 
water r and would be more appropriately termed "aerated water:" 
any medicinal effect it may possess is due to the sedative influence 
of its carbonic acid gas on the coats of the stomach. At common 
temperatures water dissolves about its own volume of carbonic acid 
gas, both being under the same pressure. One pint of the official 
soda-water contains 30 grains of bicarbonate of sodium and a pint 
of carbonic acid gas ; but the solution is under a pressure of four 
atmospheres — including the ordinary pressure of our atmosphere, 
four atmospheres altogether — so that four pints of the gas at ordi- 
nary atmospheric pressure are required for the quantity mentioned* 

Solubility of Gases in Water. — Whatever the weight and volume 
of a gas dissolved by a liquid at ordinary atmospheric pressure, that 
weight is doubled by double pressure, the two original volumes of 
gas thereby being reduced to one ; trebled at treble pressure, the 
three original volumes of gas being reduced to one; quadrupled at 
quadruple pressure, the four original volumes of gas being reduced 
to one, and so on. This is a general law (Henry and Dalton) regard- 
ing the solubility of gases in liquids under given temperatures. Aii 
average bottle of " soda-water" contains about four times the weight 
of carbonic acid gas which can exist in it without artificial pressure. 
so that on removing its cork three times its bulk escapes, its OWD 
bulk remaining dissolved. 



8b THE METALLIC RADICALS. 

Tartrate of Potassium and Sodium. 

Fifth Synthetical Reaction. — To some liot strong solution of 
carbonate of sodium (about three parts) in a test-tube or larger 
vessel add acid tartrate of potassium (about four parts), till no 
more effervescence occurs ; when the solution is cold, crystals 
of the tartrate of potassium and sodium (Potassii et Sodii Tar- 
tras, U. S. P.), the old Rochelle Salt, will be deposited — 
(KNaC 4 H 4 6 ,4H 2 0). The crystals are usually halves of right 
rhombic prisms. 

Na 2 C0 3 + 2KHC 4 H 4 6 = 2KNaC 4 H 4 6 + H 2 + C0 2 

Carbonate Acid tartrate Tartrate of potas- Water. Carbonic 

of sodium. of potassium. sium and sodium. acid gas. 

Formulae of Tartrates. 

Tartaric acid HH C 4 H 4 6 

Acid tartrate of potassium KH C 4 H 4 6 

Tartrate of potassium and sodium . . KNaC 4 H 4 6 
Very close analogy will be noticed in the constitution of the mole- 
cules of these salts. When the other tartrates come under notice, it 
will be found they also have a similar constitution. 

Hypochlorite of Sodium. 

Liquor Sodo3 Chloratas, U. S. P., " Labbaraque's Solution," is 
made by decomposing solution of carbonate of sodium by solu- 
tion of chlorinated lime ; 100 parts of the carbonate, 80 of chlo- 
rinated lime, and 820 of water. Sp. gr. 1.044. 

2Na,C0 3 + CaCl 2 ,Ca2C10 = 2(NaCl,NaC10) + 2CaC0 3 

Carbonate Chlorinated Chlorinated Carbonate of 

ot sodium. lime. soda. calcium. 

Iodide and Bromide of Sodium. 

_ These salts (NaI,NaBr), Sodii lodidum and Sodii Bromidum, are 
similar to the iodide and bromide of potassium in constitution, and 
are prepared with the same manipulations, soda being used instead 
of potash. The bromide of sodium, however, must be crystallized 
from warm solutions or rhombic prisms containing water (NaBr, 
2II 2 0) will be deposited. 

Other Sodium Compounds. 

Synthetical Reactions portraying the chemistry of the remaining 
official compounds (namely, nitrate, sulphate, hyposulphite, borate, 
arseniate, and valerianate of sodium) are deferred until the several 
acidulous radicals of these salts have been described. 

Phosphate of Sodium. — The preparation and composition of this 
salt will be most usefully studied after bone-ash, the source of it and 
other phosphates, has been described. Bone-ash is phosphate of 
calcium (sec page 109). 

The Citro-Tartrate (Sodce Citro-tartras Efervescens, B. P.) is a 
mixture of bicarbonate of sodium (17 parts), citric acid (6), and 
tartaric acid (8) 3 heated (to 200° or 220° F.) until the particles 



OTHER SODIUM COMPOUNDS. 87 

aggregate to a granular condition. When required for a medicinal 
use, a dose of the mixture is placed in water ; escape of carbonic 
acid gas at once occurs and an effervescing liquid results. This 
substance may be regarded as the official representative of the pop- 
ular "Effervescing Citrate of Magnesia," which will be further 
noticed in connection with the salts of magnesium (page 118). 

Soda poioders are formed of 30 grains of bicarbonate of sodium 
and 25 of tartaric acid wrapped separately in papers of different 
color. When mixed with water, tartrate of sodium (Na 2 C 4 H 4 6 ) 
results, a little bicarbonate also remaining. 

In the manufacture of Carbonate of Sodium from chloride, the 
source of the sodium is chloride of sodium, and of the carbonic 
radical carbonate of calcium in the form of limestone. By one 
process the chloride is first converted into sulphate, the sulphate is 
then roasted with coal and limestone, and the resulting black-ash 
lixiviated (lixivia, from lix, lye — water impregnated with alkaline 
salts ; hence lixiviation, the operation of washing a mixture with 
the view of dissolving out salts). The lye, evaporated to dryness, 
yields crude carbonate of sodium (soda-ash). By another process the 
carbonate of sodium is obtained by heating bicarbonate of sodium, 
and the latter by mixing strong solutions of chloride of sodium and 
bicarbonate of ammonium. Tlie last-named results from the action 
of carbonic acid gas (liberated on heating bicarbonate of sodium) on 
carbonate of ammonium, and this again from the reaction of heated 
mixture of chloride of ammonium and limestone. By either pro- 
cess common salt and limestone are the prime sources respectively 
of the sodium and carbonic radical in carbonate of sodium. The 
process will be further described in connection with Carbonates. 



Deliquescence and Efflorescence. — The carbonates of sodium and 
potassium, chemically closely allied, are readily distinguished phys- 
ically. Carbonate of potassium quickly absorbs moisture from the 
air and becomes damp, wet, and finally fluid — it is deliquescent (deli- 
quescens, melting away). Carbonate of sodium, on the other hand, 
yields some of its water of crystallization to the air, the crystals 
becoming white, opaque, and pulverulent — it is efflorescent (efflores- 
cens, blossoming forth). 

Analogy of Sodium Salts to Potassium Salts. — Other synthetical 
reactions might be described similar to those given under Potassium, 
and thus citrate, iodate, bromate, chlorate (Sodii Chloras, U. S. P.), 
NaC10 3 , manganate and permanganate of sodium, and many other 
salts be formed. But enough has been stated to show how anal- 
ogous sodium is chemically to potassium. Such analogies will con- 
stantly present themselves. In few departments of knowledge are 
order and method more perceptible ; in few is there as much natural 
law, as much science, as in chemistry. 

Substitution of Potassium and Sodium Salts for each other. — 
Sodium salts being cheaper than potassium salts, the former may 
sometimes be economically substituted. That one is employed rather 
than the other is often merely a result due to accident or fashion. 
But it must be borne in mind that in some cases a potassium salt 



88 THE METALLIC RADICALS. 

will crystallize more readily than its sodium analogue, or that a 
sodium salt is stable when the corresponding potassium salt has a 
tendency to absorb moisture, or one may be more soluble than the 
other, or the two may have different medicinal effect. For these or 
similar reasons, a potassium salt has come to be used in medicine 
or trade, instead of the corresponding sodium salt, and vice versa. 
Whenever the acidulous portion only is to be utilized, the least ex- 
pensive salt of the class would nearly always be selected. 

(Jj) Reactions having Analytical Interest. 

1 . The chief analytical reaction for sodium is the flame-test. 
When brought into contact with a flame in the manner de- 
scribed under potassium (page 79), an intensely yellow color 
is communicated to the flame by any salt of sodium. This is 
highly characteristic — indeed, almost too delicate a test ; for if 
the point of the wire be touched by the fingers, enough salt 
(which is contained in the moisture of the hand) adheres to 
the wire to communicate a very distinct sodium reaction. 
These statements should be experimentally verified, the chlo- 
ride, sulphate, or any other salt of sodium being employed. 

2. Sodium salts, like those of potassium, are not volatile. 
Prove this fact by the means described when treating of the 
effect of heat on potassium salts (p. 79). 



QUESTIONS AND EXERCISES. 

98. How is the official Solution of Soda prepared? Give a dia- . 
gram or equation. 

99. Explain the action of sodium or potassium on water. What 
colors do these elements respectively communicate to flame ? 

100. How much bicarbonate of sodium can be obtained from 
2240 pounds of crystallized carbonate? Ans. 1316 lbs., nearly. 

101. Acetate of Sodium : give formula, process, and equation. 

102. Give a diagram showing the formation of Bicarbonate of 
Sodium. 

103. Why is a mixture of dried and undried carbonate of sodium 
employed in the preparation of the bicarbonate ? 

104. State the difference between anhydrous and crystallized car- 
bonate of sodium. 

105. Define the terms anhydrous, hydrous, hydrate, anhydride. 

106. What do you understand by water of crystallization f 

107. What is the nature of " Soda-water" ? 

108. How many volumes of gas (reckoned as at ordinary atmo- 
spheric pressure) are contained in any given volume of the British 
official " Soda-water " ? 

109. What is the general law regarding the solubility of gases in 
liquids under pressure ? 

110. What is the systematic name of liocholle salt, and how is the 
salt prepared ? 



AMMONIUM. 89 

111. What is the relation of Rochelle salt to cream of tartar and 
tartaric acid? 

112. Give the mode of preparation and composition of Solution of 
Chlorinated Soda, and express the process by a diagram. 

113. How is the granular effervescing Citro-tartrate of Sodium 
prepared ? 

114. Define Deliquescence, Efflorescence, and Lixiviation. 

115. What is the general relation of potassium salts to those of 
sodium ? 

116. How are sodium salts analytically distinguished from those 
of potassium? 

AMMONIUM. 
Symbol NH 4 . Atomic weight 18. 

Memoranda. — The elements nitrogen and hydrogen, in the pro- 
portion of one atom to four (NH 4 ), are those characteristic of all the 
compounds about to be studied, just as potassium (K) and sodium 
(Na) are the characteristic elements of the potassium and sodium 
compounds. Ammonium is a univalent nucleus, root, or radical, like 
potassium or sodium •, and the ammonium compounds closely resemble 
those of potassium or sodium. In short, if, for an instant, potassium 
or sodium be imagined to be compounds, the analogy between these 
three series of salts is complete. Ammonium is said to have been 
isolated by Weyl, as an unstable dark-blue liquid possessing a me- 
tallic lustre. 

Source. — The source of nearly all the ammoniacal salts met with 
in commerce is ammonia-gas (NH S ) obtained in distilling coals in 
the manufacture of ordinary illuminating gas and of coke. It is 
doubtless derived from the nitrogen of the plants from which the 
coal has been produced. It is possible, however, to produce am- 
monia from its elements. Thus, coal-dust, air, and vapor of water, 
all at a red heat, yield, according to Rickman and Thompson, gaseous 
ammonia. Salt added to the mixture prevents the further combus- 
tion of the formed ammonia, and chloride of ammonium sublimes. 
Nitrogen and hydrogen passed over spongy platinum yields traces 
of ammonia. 

Ammonia. — When this gas (NIL) comes into contact with water 
(II 2 0), in the process of washing and cooling coal-gas, hydrate of 
ammonium (NIIJIO) is believed to be formed, the analogue of 
hydrate of potassium (KIIO) or sodium (NallO). The grounds 
for this belief are the observed analogy of the well-known ammo- 
niacal salts to those of potassium and sodium, the similarity of 
action of solution of potash, soda, and ammonia on salts of most 
metals, and the existence of crystals of an analogous sulphur salt 
(NH 4 HS). 

Chloride of Ammonium. — The ammonia of the "ammoniacal 
liquor" of the gas-works, liberated by heat and the concurrent ac- 
tion of lime on sulphydrate, carbonate, and other salts present, and 
passed into hydrochloric acid, yields crude chloride of ammonium 
(sal-ammoniac), 



90 THE METALLIC RADICALS. 

NH 3 + HC1 = NH 4 C1, 

and from this salt, purified, the others used in pharmacy are directly 
or indirectly made. Chloride of ammonium (Ammonii Chloridum, 
U. S. P.) occurs in colorless, inodorous minute crystals or in trans- 
lucent fibrous masses, tough, and difficult to powder, and as a snow- 
white crystalline powder, soluble in water [1 in 10 is the " Solution 
of Chloride of Ammonium," U. S. P.] and in rectified spirit. Chlo- 
ride of ammonium generally contains slight traces of oxychloride of 
iron, tarry matter, and possibly chlorides of compound ammoniums 
(vide "Artificial Alkaloids" in Index). 

Sulphate of Ammonium, (NH 4 ) 2 S0 4 , results when the ammonia 
from " ammoniacal liquor" is neutralized by oil of vitriol. It is 
largely used as a constituent of artificial manure in England, and 
when purified by recrystallization is employed in pharmacy (Ammo- 
nii Sulphas, U. S. P.). 

Volcanic Ammonia. — A very pure form of ammonia is that met 
with in volcanic districts, and obtained as a by-product in the manu- 
facture of borax ; the crude boracic acid as imported contains from 
5 to 10 per cent, of ammonium salts, chiefly sulphate, and double 
sulphates of ammonium with magnesium, sodium, and manganese 
(Howard). 

Keactions having (a) General, (6) Synthetical, and 
(c) Analytical Interest. 

Ammonium- Amalgam. (?) 

(«) General Reaction. — To forty or fifty grains of dry mer- 
cury in a dry test-tube, add one or two small pieces of sodium 
(freed from adhering naphtha by gentle pressure with a piece 
of filter-paper), and amalgamate by gently warming the tube. 
To this amalgam, when cold, add some, fragments of chloride 
of ammonium and a strong solution of the same salt. The so- 
dium amalgam soon begins to swell and rapidly increase in 
bulk, probably overflowing the tube. The light spongy mass 
produced is the so-called ammonium-amalgam, and the reaction 
is usually adduced as evidence of the existence of ammonium ; 
the sodium of the amalgam unites with the chlorine of the 
chloride of ammonium, while the ammonium is supposed to 
form an amalgam with the mercury. As soon as formed the 
amalgam gives off hydrogen and ammonia gases; this decom- 
position is nearly complete after some minutes, and impure 
mercury remains. 

(b) Reactions having Synthetical Interest. 
Hydrate of Ammonium. Ammonia. 
First Synthetical Reaction. — Heat a few grains of sal-ammo- 



AMMONIUM. 91. 

niac with about an equal weight of hydrate of calcium (slaked 
lime) dampened with a little water in a test-tube ; ammonia 
gas is given off, and may be recognized by its well-known 
odor. It is very soluble in water. Pass a delivery-tube, 
fitted to the test-tube as described for the preparation of oxy- 
gen and hydrogen, into a second test-tube, at the bottom of 
which is a little water ; again heat, the end of the delivery- 
tube being only just beneath the surface of the water (or, pos- 
sibly, all the water might rush into the generating-tubes, water 
absorbing ammonia gas with great avidity) ; solution of ammo- 
nia will be thus formed. 



2NH 4 C1 


+ 


Ca2HO = 


= CaCl 2 + 


2H 2 


+ 2NH 3 


Chloride, of 




Hydrate of 


Chloride of 


Water. 


Ammonia 


ammonium. 




calcium. 


calcium. 




gas. 



Ammonia gas is composed of one atom of nitrogen with three 
atoms of hydrogen ; its formula is NH 3 ; two volumes of it contain 
one volume of nitrogen combined with three atoms or volumes of 
hydrogen. Its constituents have therefore in combining suffered 
condensation to one half their normal bulk. Its conversion into 
hydrate of ammonium may be thus shown : — 



NH 3 


+ 


H 2 = 


= NH 4 HO or AmHO 


Ammoni; 




Water. 


Hydrate of ammonium 


gas. 






(ammonia). 



Solutions of Ammonia, prepared by this process on a large scale 
and in suitable apparatus, are met with in pharmacy — the one (sp. 
gr. 0.900) containing 28 per cent., the other (sp. gr. 0.959), 10 per 
cent., by weight, of ammonia gas, NH 3 (Aqua Ammoni ce Fortior and 
Aqua Ammonice, U. S. P.). On the large scale, bottles are so ar- 
ranged in a series as to condense all the ammonia evolved during 
the operation. 

Acetate of Ammonium. 

Second Synthetical Reaction. — To acetic acid and water in 
a test-tube, add powdered commercial carbonate (acid carbon- 
ate and carbamate) of ammonium till effervescence ceases ; the 
resulting liquid, made of prescribed strength, is the official 
solution of Acetate of Ammonium (NH 4 C 2 H. .,().,) (Liquor Am- 
monii Acrtatis, U. S. P.), the old " Spirit of Mindererus." 

NH 4 HC0 3 , NH + NH 2 CO, + 3HC 2 H,0 2 = 3NH 4 C a H,O a 

Acid carbonate and carbamate Acetic acid. Acetate of 

of ammonium. ammonium. 

+ H 2 + 2CO a 

Water. Carbonic acid gas. 

Carbonates of Ammonium. 
Commercial carbonate of ammonium is made by heating a mixture 
of chalk and sal-ammoniac j chloride of calcium (CaClj) is produced. 
ammonia, gas (Nil.,) and water (H a O) escape, and the ammoniaca! 



92 THE METALLIC RADICALS. 

carbonate distils, or rather sublimes,* in cakes (Ammonii Carbonas, 
U. S. P.). The best form of apparatus to employ is a retort with a 
short wide neck and a cool receiver. On the large scale the retort 
is usually iron and the receiver earthenware or glass ; on the small 
scale glass vessels are employed. The salt is purified by resublima- 
tion at a low temperature ; 150° F. is said to be sufficient. 

This salt, the empirical formula of which is N 3 H u C 2 5 , is probably 
a mixture of one molecule (sometimes two) of acid carbonate or bi- 
carbonate of ammonium (NH 4 HC0 3 ) and one of a salt termed carba- 
mate of ammonium (NH 4 NH 2 C0 2 ). The latter belongs to an import- 
ant class of salts known as carbamates, but it is the only one of inte- 
rest to the pharmacist. Cold water extracts it from the commercial 
carbonate of ammonium, leaving the acid carbonate of ammonium 
undissolved, if the amount of liquid used be very small. Alcohol ex- 
tracts the carbamate, leaving the acid carbonate undissolved. In water, 
carbamate soon changes into neutral carbonate of ammonium, 

NH 4 NH 2 C0 2 + H 2 = (NHJ 2 C0 3 or Am 2 C0 3 ; 
so that an aqueous solution of commercial carbonate of ammonium 
contains both acid carbonate and neutral carbonate of ammonium. 
If to such a solution some ordinary solution of ammonia be added, a 
solution of neutral carbonate of ammonium is obtained 5 and this is 
the common reagent always found on the shelves of the analytical 
laboratory. 

NH 4 HC0 3 + NH 4 HO = (NlLj 2 C0 3 + H 2 0. 
Neutral carbonate of ammonium is the salt formed on adding strong 
solution of ammonia to the commercial carbonate in preparing a 
pungent mixture for toilet smelling-bottles ; but it is unstable, and 
on continued exposure to air is reduced to a mass of crystals of the 
acid carbonate or bicarbonate of ammonium. Bicarbonate of ammo- 
nium (NH^HCOg) is also produced on passing carbonic acid gas into 
an aqueous solution of commercial carbonate. 

According to Divers, the sublimed product of the first distillation 
of chalk and sal-ammoniac is a mixture of carbamate and carbonate 
of ammonium, the latter losing some ammonia gas on redistillation, 
and carbamate with bicarbonate forming the resulting commercial 
salt. 

If carbonate of ammonium contain more than traces of empyreu- 
matic matters (derived primarily from the gas-liquors), an aqueous 
solution, with excess of sulphuric acid added, will decolorize a dilute 
solution of permanganate of potassium at once. 

Sal Volatile (Spiritus Ammonia Aromaticus ) U. S. P.) is a spirit- 
uous solution of ammonia (AmllO), neutral carbonate of ammonium 
(Am 2 C0 3 ), and the oils of lemon, lavender and pimenta. Fetid 
spirit of ammonia (Spiritus Ammonia? Foetidus, B. P.) is an alco- 
holic solution of the volatile oil of asafcetida mixed with solution 
of ammonia. " Solution of Carbonate of Ammonia," B. P., is formed 

* Sublimation (from sublimis, high). Vaporization of a solid sub- 
stance by heat, and its condensation on an upper and cooler part of 
the vessel or apparatus in which the operation is performed. 



AMMONIUM. 93 

by dissolving 1 part of the salt in 10 of water. Spiritus Ammonia?, 
U. S. P., is an alcoholic solution of ammonia containing 10 per cent., 
by weight, of gas (NH 3 ). 

Nitrate of Ammonium. 

Third Synthetical Reaction. — To some diluted nitric acid 
add carbonate of ammonium, until, after well stirring, a slight 
ammoniacal odor remains. The solution contains Nitrate of 
Ammonium (Ammonii Nitras, U. S. P.) 

NH 4 HC0 3 , NH 4 NH 2 C0 2 + 3HN0 3 = 3frH 4 N0 3 + H 2 + 2CO 

Acid carbonate and carbamate Nitric Nitrate of Water. Carbonic 

of ammonium. acid. ammonium. acid gas. 

From a strong hot solution of nitrate of ammonium crystals may 
be obtained containing much water (NH 4 N0 3 , 12H 2 0). On heating 
these to about 320° F. the water escapes. The anhydrous salt re- 
maining (NH 4 N0 3 ) may be poured on to an iron plate. On further 
heating the powdered nitrate, at 35O°-450° F., it is resolved into 
nitrous oxide gas (the so-called laughing gas) and water. 

NH 4 N0 3 = N 2 + 2H 2 0. 

Nitrous oxide is thus prepared for use as an anaesthetic. When 
required for inhalation, it should be washed from any possible trace 
of acid or nitric oxide, by being passed through solution of potash, 
and through solution of ferrous sulphate, the former absorbing acid 
vapors and the latter nitric oxide. 

Nitrous oxide is slightly soluble in warm water, more so in cold. 
It supports combustion almost as well as oxygen. By pressure it 
may be liquefied to a colorless fluid, and by simultaneous cooling 
solidified. 

Citrate, Phosphate, and Benzoate of Ammonium. 

Fourth Synthetical Reaction. — To solution of citrate acid 
(H 3 C 6 H 5 7 ) add solution of ammonia (NH 4 HO) until the 
well-stirred liquid smells faintly of ammonia. Solutions 
having the specific gravities, respectively, of 1.062 (four 
times the strength) and 1.209 form the official Solutions of Cit- 
rate of Ammonium (NH 4 ) 3 C (i H 5 7 , Liquor Ammonise Oitratis, 
B. P., and Liquor Ammonii Oitratis Fortior, B. P. 

Phosphate of Ammonium, NIIJIPO, {Am mom'/ Phosphas, U. S. 
P.), and Benzoate of Ammonium, NH 4 C 7 H-0 2 (Ammonii Benzoas, 
U. S. P.), are also made by adding solution of ammonia to phos- 
phoric acid (H 3 P0 4 ) and benzoic acid (II(\H-0 2 ) respectively, evap- 
orating (keeping the ammonia in slight excess by adding more of its 
solution), and setting aside for crystals to form. 

IMY.HA + 3NH 4 HO = (XH.yvH.A 311..0 

Citric acid. Ammonia. Citrate <»t" aiimmhium. Watrr 



94 THE METALLIC RADICALS. 

H,P0 4 + 2NH 4 HO = (XH 4 ) 2 HP0 4 + 2H 2 

Phosphoric acid. Ammonia. Phosphate of ammonium. V, ater. 

IIC-H 5 2 + XH 4 HO = NH 4 C T H 5 2 + H 2 

Benzoic acid. Ammonia. Benzoate of ammonium. "W ater. 

Phosphate of ammonium occurs in transparent colorless prisms, 
soluble in water, insoluble in spirit ; benzoate in crystalline plates, 
soluble in water and in spirit. 

Ammonii Indicium, U. S. P., may be made by decomposing the 
two bodies iodide of potassium and sulphate of ammonium, which 
give iodide of ammonium and sulphate of potassium ; the latter 
salt is separated by adding alcohol to the cooled solution, when, by 
reason of its insolubility in alcohol, it crystallizes out, and the sep- 
arated solution of iodide of ammonium is then evaporated to dry- 
ness. It occurs usually in minute white crystalline cubes. 

Bromide of Ammonium (Ammonii Bromidum. U. S. P.) will be 
noticed in connection with Hydrobromic Acid and other Bromides. 

Oxalate of Ammonium. 
Fifth Synthetical Reaction. — To a nearly boiling solution of 1 
part of oxalic acid in about 8 of water add carbonate of am- 
monium until the liquid is neutral to test-paper (see following 
paragraph), filter while hot, and set aside for crystals to form. 
The product is oxalate of ammonium. (XH 4 ) 2 C 2 4 H 2 0. The 
mother-liquor is useful as a reagent in analysis ; 1 of the pure 
salt in 20 of water constitutes " Solution of Oxalate of Am- 
monium," U. S. P. 

3H 2 CA + 2N 3 H n C 2 5 = 3(XH + \CA + 4C0 2 + 2H 2 

Oxalic Carbonate of Oxalate of Carbonic Water, 

acid. ammonium. ammonium. acid gas. 

Neutralization. — Thus far, in reactions, the methods by which the 
student has avoided excess of either acid matter on the one hand, or 
alkaline matter on the other, have been the rough aid of taste, ces- 
sation of effervescence, presence or absence of odor, etc. More del- 
icate aid is afforded by test-papers. 

Test-papers. — Litmus is a blue vegetable pigment, prepared from 
various species of Roccella lichen, exceedingly sensitive to the action 
of acids, which turn it red. When thus reddened, alkalies (potash, 
soda, and ammonia) and other soluble hydrates readily turn it blue. 
The student should here test for himself the delicacy of this action 
by experiments with paper soaked in solution of litmus and dipped 
into very dilute solutions of acids, acid salts (KHC 4 H 4 6 , e. #.), alka- 
lies, and such neutral salts as nitrate of potassium, sulphate of so- 
dium, or chloride of ammonium. 

Solution of Litmus (U. S. P.). — This is prepared from purified lit- 
mus. Gently boil litmus with three times its bulk of spirit of wine 
for an hour. Pour away the fluid and repeat the operation twice. 
Digest the residual litmus in distilled water-filter. 



AMMONIUM. 95 

Blue litmus paper (U. S. P.) is " unsized white paper colored with 
solution of litmus." Red litmus paper (U. S. P.) is "unsized white 
paper colored with solution of litmus previously reddened by the 
smallest requisite quantity of sulphuric acid." 

Turmeric paper (U. S. P.), similarly prepared from Tincture of Tur- 
meric (1 of turmeric root or rhizome to 6 of diluted alcohol, mace- 
rated for seven days), is occasionally useful as a test for alkalies, 
which turn its yellow to brown 5 acids do not affect it. 

Sulphydrate of Ammonium. 

Sixth Synthetical Reaction. — Pass sulphuretted hydrogen 
gas (H 2 S) through a small quantity of solution of ammonia in 
a test-tube, until a portion of the liquid no longer causes a 
white precipitate in solution of sulphate of magnesium (Epsom 
salt) ; the product is solution of sulphydrate (or sulphide) of 
ammonium (NH 4 HS), the " Solution of Sulphide of Ammo- 
nium," U. S. P., a most valuable chemical reagent, as will 
presently be apparent. 

NH 4 HO + H 2 S = NHJHS + H 2 0. 

" Test-Solution of Sulphide of Ammonium" U. S. P., is made by 
passing the gas prepared in the apparatus described below into 3 
fiuidounces of Water of Ammonia so long as the gas continues to 
be absorbed, then adding 2 more ounces of the ammonia, and pre- 
serving the solution in a well-stoppered bottle. 

Sulphuretted! hydrogen is a compound of noxious odor ; 
hence the above operation, and many others, described further 
on, in which this gas is indispensable, can only be performed 
in the open air, or in a fume-cupboard, a chamber so contrived 
that deleterious gases and vapors shall escape into a chimney 
in connection with the external air. In the above experiment, 
the small quantity of gas required can be made in a test-tube, 
after the manner of hydrogen itself. To two or three frag- 
ments of sulphide of iron (FeS), add water and then sulphuric 
acid ; the gas is at once evolved, and may be conducted by a 
tube into the solution of Ammonia. Sulphate of iron remains 
dissolved in the water. 

FeS + H 2 S0 4 - H 2 S + FeSO,. 

Crystals of sulphydrate of ammonium (NIFJIS) may be obtained 
on bringing ammonia gas (NH 3 ) and sulphuretted hydrogen (H 2 S) 
together at a low temperature. They are soluble in water without 
decomposition. 

Sulphuretted-Hydrogen Apparatus. — As no heat is necessary 

in making sulphuretted hydrogen, the test-tube oi' the fore- 
going operation may be advantageously replaced by a bottle. 



96 



THE METALLIC RADICALS. 



especially when larger quantities of the gas are required. 
In analytical operations the gas should be purified by passing 
it through water contained in a second bottle. 

The most convenient arrangement for experimental use is 
prepared as follows : Two common wide-mouthed bottles are 
selected, the one having a capacity of about half a pint, the 
other a quarter pint ; the former may be called the generating- 
bottle, the latter the wash-bottle. Fit two corks to the bottles. 
Through each cork bore two holes by a round file or other 
instrument of such a size that glass tubing of about the diam- 
eter of a quill pen shall fit them tightly. Through one of the 
holes in the cork of the generating-bottle pass a funnel-tube, so 
that its extremity may nearly reach the bottom of the bottle. 
To the other hole adapt a piece of tubing. 6 inches long, and 
bent in the middle to a right angle. A similar " elbow-tube " 
is fitted to one of the holes in the cork of the wash-bottle, and 
another elbow-tube, one arm of which is long enough to reach 
to near the bottom of the wash-bottle, fitted to the other hole. 
Kemoving the corks, two or three ounces of water are now 
poured into each bottle, an ounce or two of sulphide of iron put 
into the generating-bottle. and the corks replaced. The elbow- 
tube of the generating-bottle is now attached by a short piece 
of India-rubber tubing to the long-aimed elbow-tube of the 



Fig. 18. 




Sulphuretted-Hydrogen Apparatus. 

wash-bottle, so that gas coming from the generator may pass 
through the water in the wash-bottle. The delivery-tube of 
the wash-bottle is then lengthened by attaching to it. by India- 
rubber tubing, another piece of glass tubing several inches in 
length. The apparatus is now ready for use. Strong sulphuric 
acid is poured down the funnel-tube in small quantities at a 
time, until brisk effervescence is established, and more added 



AMMONIUM. 97 

from time to time as the evolution of gas becomes slow. The 
gas passes through the tubes into the wash-bottle, where, as it 
bubbles up through the water, any trace of sulphuric acid, or 
other matter mechanically carried over, is arrested, and thence 
the gas flows out at the delivery-tube into any vessel or liquid 
that may be placed there to receive it. The generator must be 
occasionally dismounted and the sulphate of iron washed out. 

Luting (latum, mud). — If the corks of the above apparatus are 
sound, and tube-holes well made, no escape of gas will occur. If 
rough corks have been employed, or the holes are not cylindrical, 
linseed-meal lute may be rubbed over the defective parts. The lute 
is prepared by mixing linseed-meal with water to the consistence of 
dough. A neat appearance may be given to the lute by gently rub- 
bing a well-wetted finger over its surface. 

(c) Reactions having Analytical Interest (Tests'). 

First Analytical Reaction* — To a solution of any salt of am- 
monium (the chloride, for example) in a test-tube, add solution 
of caustic soda (or solution of potash, or a little slaked lime) ; 
ammonia gas is at once evolved, recognized by its well-known 
odor. 

NH 4 C1 + NaHO = NH 3 + H 2 + NaCl. 

Though ammonium itself cannot be kept in the free state, its com- 
pounds -are stable. Ammonia is easily expelled from these com- 
pounis by action of the stronger alkalies, caustic potash, soda, or 
lime. As a matter of exercise, the student should here draw out 
equations in which acetate (NH 4 C 2 H 3 2 ), sulphate ((NH 4 ) 2 S0 4 ), nitrate 
(NH 4 N0 3 ) or any other ammoniacal salt not already having the 
odor of ammonia, is supposed to be under examination ; also rep- 
resenting the use of the other hydrates, potash (KIIO) or slaked lime 
(Ca2HO). 

The odor of ammonia gas is perhaps the best means of rec- 
ognizing its presence ; but the following tests are also occa- 
sionally useful. Into the test-tube in which the ammonia gas 
is evolved insert a glass rod moistened with hydrochloric acid 
(that is, with the solution of hydrochloric acid gas, conveniently 
termed hydrochloric acid, the Acidum Ilydroclrforicum of the 
Pharmacopoeias) ; white fumes of chloride of ammonium will 
be produced. 

NH, + HC1 = NH 4 C1. 

Hold a piece of moistened red litmus paper in a tube in which 

ammonia gas is present; the red color will be changed to blue. 

Second Analytical Reaction. — To a few drops oi' a solution 

of an ammonium salt add a drop or two of hydrochloric acid 



98 



THE METALLIC RADICALS. 



and a like small quantity of solution of perchloride of platinum 
(PtCl 4 ) ; a yellow crystalline precipitate of the double chloride 
of platinum and ammonium (PtCl 4 2NH 4 Cl) will he produced, 
similar in appearance to the corresponding salt of potassium, 
the remarks concerning which (p. 78) are equally applicable 
to the precipitate under notice. 

Third Analytical Reaction. — To a moderately strong solu- 
tion of an ammonium salt add a strong solution of tartaric 
acid, and shake or well stir the mixture ; a white granular 
precipitate of acid tartrate of ammonium will be formed. 

For data from which to draw out an equation representing this 
action, see the remarks and formulas under the analogous salt of 
potassium (p. 77). 

Fourth Analytical Fact. — Evaporate a few drops* of a solu- 
tion of an ammonium salt to dryness, or place a fragment of a 
salt in the solid state on a piece of platinum foil, and heat in 
a flame ; the salt is readily volatilized. As already noticed, the 
salts of potassium and sodium are fixed under these circum- 
stances, a point of difference of which advantage will frequently 
be taken in analysis. A porcelain crucible may often be ad- 
vantageously substituted for platinum foil in experiments on 
volatilization. 

Salts of ammonium with the more complex acidulous radicals 
seldom volatilize unchanged when heated. The oxalate, when 
warmed, loses its water of crystallization, and at a higher tem- 
perature decomposes, yielding carbonic oxide, carbonic acid 
gas, ammonia gas, water (the three latter sometimes in combi- 
nation), and several organic substances. The phosphate yields 
more or less phosphoric acid as a residue. 



Fig. 19, 



Fig. 20. 



Fig. 21. 




Triangular Supports for Crucibles. 
A wire triangle may be used in supporting crucibles. It is made 



AMMONIUM. 99 

by twisting together each pair of ends of three (5 or 6 inch) crossed 
pieces of wire (Fig. 20). A piece of tobacco-pipe stem (about 2 
inches) is sometimes placed in the centre of each wire before twist- 
ing, the transference of any metallic matter to the sides of the cru- 
cible being thus prevented (Fig. 21). 

Practical Analysis. 

With regard to those experiments which are useful rather as means 
of detecting the presence of potassium, sodium, and ammonium, than 
as illustrating the preparation of salts, the student should proceed 
to apply them to certain solutions of any of the salts of potassium, 
sodium, and ammonium, with the view of ascertaining which metal 
is present ; that is, proceed to practical analysis.* A little thought 
will enable him to apply these reactions in the most suitable order 
and to the best advantage for the contemplated purpose : but the 
following arrangements are perhaps as good as can be devised : — 

directions for applying the foregoing analytical re- 
actions to the analysis of an aqueous solution of 
a salt of one of the metaljs, potassium, sodium, 
Ammonium. 

Add caustic soda to a small portion of the solution to be 
examined, and warm the mixture in a test-tube ; the odor of 
ammonia gas at once reveals the presence of an ammonium 
salt. 

If ammonium be not present, apply the perchloride-of-plat- 
inum test to another portion of the liquid ; a yellow precipitate 
proves the presence of potassium. 

(It will be observed that potassium can only be detected in 
the absence of ammonium, salts of the latter radical giving 
similar precipitates.) 

The flame-test is sufficient for the recognition of sodium. 

* Such solutions are prepared in educational laboratories by a tutor. 
They should, under other circumstances, be mixed by a friend, as it is 
not desirable for the student to know previously what is contained in 
the substance he is about to analyze. 

The analysis of solutions containing only one salt serves to impress 
the memory with the characteristic tests for the various metals and 
other radicals, and familiarize the mind with chemical principles 
Medical students seldom have time to go further than this. More 
thorough analytical and general chemical knowledge is only acquired 
by working on such mixtures of bodies as are met with in actual prac- 
tice, beginning with solutions which may contain any or all the mem- 
bers of a group. Hence in this Manual two Tables oi' short directions 
for analyzing are given under each group. Pharmaceutical students 
should follow the second Table. 



100 THE METALLIC EADICALS. 

DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL RE- 
" ACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF 

SALTS OF ONE, TWO, OR ALL THEEE OF THE ALKALI 

METALS. 

Commence by testing a small portion of the solution for an 
ammonium salt. If present, make a memorandum to that effect, 
and then proceed to get rid of the ammoniacal compound to 
make way for the detection of potassium : advantage is here 
taken of the volatility of ammonium salts and the fixity of those 
of potassium and sodium. Evaporate the original solution to 
dryness in a small basin, transfer the solid residue to a porce- 
lain crucible, and heat the latter to a low redness, or until dense 
white fumes (of ammoniacal salts) cease to escape. (See Fig. 
19.) This operation should be conducted in a fume-cupboard, 
to avoid contamination of the air of the apartment. When the 
crucible is cold, dissolve out the solid residue with a small 
quantity of hot water, and test the solution for potassium by 
the perchloride-of-platinum test, and for sodium by the flam& 
test. 

If ammonium is proved to be ' absent, the original solution 
may, of course, at once be tested for potassium and sodium. 

Flame-test. — The violet tint imparted to flame by potassium salts 
may be seen when masked by the intense yellow color due to sodium, 
if the flame be observed through a piece of dark-blue glass, a medium 
which absorbs the yellow rays of light. 

Note on Nomenclature. — The operations of evaporation and heat- 
ing to redness, or ignition, are frequently necessary in analysis, and 
are usually conducted in the above manner. If vegetable or animal 
matter be also present, carbon is set free, and ignition is accom- 
panied by carbonization ; the material is said to char. When all 
carbonaceous matter is burnt off, the crucible being slightly inclined 
and its cover removed to facilitate combustion, and mineral matter, 
or ash, alone remains, the operation of incineration has been effected. 

Note on the Classification of Elements. — The compounds of potas- 
sium, sodium, and ammonium have manj' analogies. Their carbon- 
ates, phosphates, and other common salts are soluble in water. The 
atoms of the radicals themselves are univalent — that is, displace or are 
displaced by one atom of hydrogen. In fact, these radicals constitute 
by their similarity in properties a distinct group or family. All the 
elements thus naturally fall into classes— a fact that should con- 
stantly be borne in mind, and evidence of which should always be 
sought. _ It would be impossible for the memory to retain the details 
of chemistry without a system of classification and leading princi- 
ples. Classification is also an important feature in the art as well 
as in the science of chemistry; for without it practical analysis 



AMMONIUM. 101 

could not be undertaken. The classification adopted in this volume 
is founded on the quantivalence of the elements and on their ana- 
lytiial relations. 



QUESTIONS AND EXERCISES. 

117. Why are ammoniacal salts classed with those of potassium 
and sodium? 

118. Mention the sources of the ammonium salts. 

119. Describe the appearance and other characters of Chloride of 
Ammonium. 

120. Give the formula of Sulphate of Ammonium. 

121. Adduce evidence of the existence of ammonium. 

122. How are the official Waters of Ammonia prepared? Give 
diagrams. 

123. How is the official Solution of Acetate of Ammonium pre- 
pared ? 

124. What is the composition of commercial Carbonate of Ammo- 
nium? 

125. Define sublimation. 

126. What ammoniacal salts are contained in Spiritus Ammonice 
Aromaticus f 

127. Give diagrams or equations illustrating the formation of 
Citrate, Phosphate, and Benzoate of Ammonium? 

128. Give the formula of Oxalate of Ammonium. 

129. Show how Hydrate of Ammonium may be converted into 
Sulphydrate. 

13(T Describe the preparation of Sulphuretted Hydrogen gas. 

131. Enumerate and explain the tests for ammonium. 

132. How is potassium detected in a solution in which ammonium 
has been found ? 

133. Give equations illustrating the action of hydrate of sodium 
on acetate of ammonium ; hydrate of potassium on sulphate of am- 
monium ; and hydrate of calcium on nitrate of ammonium. 

134. What are the effects of acids and alkalies on litmus and 
turmeric ? 

135. Describe the analysis of an aqueous liquid containing salts 
of potassium, sodium, and ammonium. 

136. What meanings arc commonly assigned to the terms evapor- 
ation, ignition, carbonization, and incineration? 

137. Write a short article descriptive of the analogies of potas- 
sium, sodium, and ammonium, and their compounds. 

9* 



102 THE METALLIC RADICALS. 

BARIUM, CALCIUM, MAGNESIUM. 

These three elements have many analogies. Their atoms are 
bivalent. 

BARIUM. 
Symbol Ba. Atomic Aveight 136.8. 
The analytical reactions only of this metal are of interest to the 
general student of pharmacy. The nitrate (Ba2N0 3 ) and the chlo- 
ride (BaCl 2 .2H.,0) are the soluble salts in common use in anclvsis 
(" Test-Solution of Chloride of Barium,"' 1 in 10 of water, U. S. P.) •, 
and these and others are made by dissolving the native carbonate 
(BaC0 3 ), the mineral witherite, in acids, or by heating the other 
common natural compound of barium, the sulphate, heavy white or 
heavy spar (BaS0 4 ), with coal, which yields sulphide of barium (BaS) ? 
BaS0 4 +-C 4 = 4CO-l-BaS, 

and dissolving the sulphide m appropriate acids. When the nitrate 
is strongly heated, it is decomposed, the oxide of barium or baryta 
(BaO) remaining. Baryta, on being moistened, assimilates the ele- 
ments of water with great avidity, and yields hydrate of barium 
(Ba2HO). The latter is tolerably soluble, giving baryta-water; 
and from this solution crystals of hydrate of barium are obtained 
on evaporation. 

The operations above described may all be performed in test-tubes 
and small porcelain crucibles heated by the gas-flame. Quantities of 
1 oz. to 1 lb. require a coke-furnace. 

Peroxide of barium (Ba0 2 ) is formed on passing air over baryta 
heated to about 600° F. On raising the temperature, oxygen is 
evolved and baryta remains. This is Boussingault's old process. 
But the baryta loses its absorbing power after a time. If the air be 
freed from carbonic acid gas and the peroxide be not exposed to a 
much higher temperature than 800° F. (by heating in a vacuum), the 
baryta can be used over and over again. This improvement is by 
Messrs. Brin, who sell the oxygen compressed within strong metal 
cylinders. By the action of dilute hydrochloric acid it yields solu- 
tion of peroxide of hydrogen (H 2 2 ), the old oxygenated water. On 
neutralizing solution of peroxide of hydrogen with ammonia and 
adding permanganate of potassium, oxygen gas is evolved, its vol- 
ume indicating the oxygen-strength of the original solution. 

Reactions having Analytical Interest (Tests). 
First Analytical Reaction. — To the aqueous solution of any 
soluble salt of barium (nitrate or chloride, for example) add 
dilute sulphuric acid ; a white precipitate is obtained. Set the 
test-tube aside for two or three minutes, and when some of the 
precipitate has fallen to the bottom pour away the supernatant 
liquid ; wash the precipitate by adding water, shaking, setting 
aside, and again decanting ; then add strong nitric acid, and 
boil ; the precipitate is insoluble. 



BARIUM. 103 

The production of a white precipitate by sulphuric acid, insoluble 
even in hot nitric acid, is highly characteristic of barium. The name 
of this precipitate is sulphate of barium ; its formula is BaS0 4 . 

Antidotes. — In cases of poisoning by soluble barium salts, obvious 
antidotes would be solutions of alum or of any sulphates, such as 
those of magnesium and sodium (Epsom salt, Glauber's salt). 

Second Analytical Reaction. — To a barium solution add 
solution of the yellow chromate of potassium (K 2 CrQ 4 ) ; a pale 
yellow precipitate (BaCr0 4 ) falls. Add acetic acid to a por- 
tion of the chromate of barium ; it is insoluble. Add hydro- 
chloric or nitric acid to another portion ; it is soluble. 

" Neutral Chromate.'''' — The red chromate (or bichromate) of po- 
tassium (K 2 Cr0 4 ,Cr0 3 ) must not be used in this reaction, or the 
barium will be only imperfectly precipitated ; for the red salt gives 
rise to the formation of free acid, in which chromate of barium is to 
some extent soluble : — 

K 2 Cr0 4 ,Cr0 3 -f 2BaCl 2 + H 2 = 2BaCrG 4 -j- 2KC1 + 2HC1. 

Yellow chromate is obtained on adding bicarbonate of potassium, 

in small quantities at a time, to a hot solution of the -red chromate 

until effervescence ceases ; a little more red chromate is then added to 

ensure decomposition of any slight excess of carbonate of potassium. 

K 2 Cr0 4 ,Cr0 3 + 2KHC0 3 = 2K 2 Cr0 4 + 2C0 2 -f H 2 0. 

For analytical purposes, solution of a neutral chromate is still 
more readily prepared by simply adding solution of ammonia to 
solution of red chromate of potassium, until the liquid turns yel- 
low, and, after stirring, smells of ammonia. 

K 2 Cr0 4 ,Cr0 3 + 2NH 4 HO = 2KNH 4 Cr0 4 + H 2 0. 
Other Analytical Reactions. — To a barium solution add a 
soluble carbonate (carbonate of ammonium ((NH 4 ) 2 C0 3 ~) will 
generally be rather more useful than others) ; a white precipi- 
tate of carbonate of barium (BaC0 3 ) results. To more of 

the solution add an alkaline phosphate or arseniate (phosphate 
of sodium (Na 2 HP0 4 ) is the most common of these chemically 
analogous salts, but phosphate of ammonium (Am 2 HP0 4 ) 01 
arseniate (NH 4 HAs0 4 ) will subsequently have the preference) ; 
white phosphate of barium (BaHP0 4 ), insoluble in pure water, 
but slightly soluble in aqueous solutions of some salts, or 
arseniate of barium (BaHAs0 4 ), both soluble even in acetic 

and other weak acids, are precipitated. To another portion 

add oxalate of ammonium ((NII 4 ) 2 C,0 4 ) ; white oxalate of barium 
(BaC 2 4 ) is precipitated, soluble in the diluted mineral acids, 

and sparingly so in acetic acid. The silico-tiuoride of barium 

(BaSiF 6 ) is insoluble, and falls readily if an equal volume oi" 
spirit of wine be added to the solution under examination after 






104 THE METALLIC RADICALS. 

the addition of hydrofluosilicic acid (H 2 SiF 6 ). Barium salts, 

moistened with hydrochloric acid, impart a greenish color to 
flame. 

Mem. — Good practice will be found in writing out equations de- 
scriptive of each of the foregoing reactions. 



QUESTIONS AXD EXERCISES. 

138. What is the quanti valence of barium ? 

139. Write down the formulas of oxide, hydrate, chloride, nitrate, 
carbonate, and sulphate of barium ; and state how these salts are 
prepared. 

140. Describe the preparation of peroxide of hydrogen. 

141. Which of the tests for barium are most characteristic? Give 
an equation of the reactions. 

142. Name the antidote in cases of poisoning by soluble barium 
salts, and explain its action. 

CALCIUM. 

Symbol Ca. Atomic weight 40. 
Calcium compounds form a large proportion of the crust of our 
earth. Carbonate of calcium is met with as chalk, marble, lime- 
stone, calc-spar, etc. ; the sulphate, as eypsum or plaster of Paris 
(native sulphate of calcium — CaS0 4 ,2H 2 — rendered nearly anhy- 
drous by heat), and alabaster ; the silicate in many minerals ; the 
fluoride of calcium as fluor-spar. The phosphate is also a common 
mineral. The element itself is only isolated with great difficulty. 
The atom of calcium is bivalent, Ca". 

Reactions having Synthetical Interest. 
Chloride of Calcium. 
First Synthetical Reaction. — To some hydrochloric acid add 
carbonate of calcium (chalk, or, the purer form, white marble) 
(CaC0 3 ) until effervescence ceases, filter; solution of chloride 
of calcium (CaCl 2 ), the most common soluble salt of calcium, 
is formed. 



CaC0 3 


+ 2HC1 = 


= CaCl 2 


+ 


H 2 


+ 


co 2 


Carbouate of 


Hydrochloric 


Chloride of 




Water. 




Carbonic 


calcium. 


acid. 


calcium. 








acid gas. 



This solution contains carbonic acid, and will give a precipitate 
of carbonate of calcium on the addition of lime-water. It may be 
obtained quite neutral by well boiling before filtering off the excess 
of marble. It is a serviceable test-liquid in analytical operations. 

Solution of chloride of calcium evaporated to a syrupy consist- 
ence readily yields crystals (CaCl 2 ,6H 2 0). These are extremely 
deliquescent. The solution, evaporated to dryness, and the white 
residue heated to about 200° C, gives solid chloride of calcium 



CALCIUM. 105 

(CaCl 2 ,2H 2 0) in a porous form. The resulting agglutinated lumps 
(Calcii Chloridum, U. S. P.) are much used for drying gases and for 
freeing certain liquids from water. The salt is soluble in alcohol. 
One part of the salt in ten of water constitutes a useful test-liquid, 
" Test-solution of Chloride of Calcium," U. S. P. 

Mem. — The practical student has already met with solution of 
chloride of calcium as a by-product or secondary product in the 
preparation of carbonic acid gas. 

Marble often contains ferrous carbonate (FeC0 3 ), which in 
the above process becomes converted into ferrous chloride, 
rendering the chloride of calcium impure : — 



FeC0 3 


+ 2HC1 = 


FeCl 2 


+ 


H 2 


+ co 2 


Ferrous 


Hydrochloric 


Ferrous 




Water. 


Carbonic 


carbonate. 


acid. 


chloride. 






acid gas. 



If absolutely pure chloride of calcium be required, a few 
drops of the solution should be poured into a test-tube or test- 
glass, diluted with water, and examined for iron (by adding 
sulphydrate of ammonium, which gives a black precipitate with 
salts of iron), and, if the latter is present, hypochlorite of cal- 
cium (in the form of chlorinated lime) and slaked lime should 
be added to the remaining bulk of the liquid, and the whole 
boiled for a few minutes, whereby iron (as ferric hydrate) is 
thus precipitated ; on filtering, a pure solution of chloride of 
calcium is obtained : — 

^4FeCl 2 + Ca2C10 + 4CaH 2 2 + 2H,0 

Ferrous Hypochlorite Hydrate of Water. 

chloride. of calcium. calcium. 

= 2(Fe 2 6HO) + 5CaCl 2 

Ferric ' Chloride 

hydrate. of calcium. 

This is the official process, and may be imitated on the small 
scale after adding a minute piece of iron to a fragment of the 
marble before disolving in acid. 

The names, formulae, and reactions of these compounds of iron 
will be best understood when that metal comes under treatment. 

Oxide of Calcium (Quick Lime). 
Second Synthetical Reaction. — Place a small piece of chalk 
in a strong grate-fire or furnace and heat until a trial fragment 
chipped on' from time to time and cooled, no longer effervesces 
on the addition of acid; caustic lime, CaO (Cafe, V S. P.), 
remains. 

CaC0 3 = CaO + CO, 

Carbonateof Oxide of Carbonic 

calcium (chalk). calcium (lime). acid gas. 



106 THE METALLIC RADICALS. 

Note. — Etymologically considered, this action is analytical (ava?.vo), 
analuo, I resolve) and not synthetical (gvvOegic, sunthesis, a putting 
together) 5 but conventionally it is synthetical, and not analytical ; 
for in this, the usual sense, synthesis is the application of chemical 
action with the view of producing something, analysis the applica- 
tion of chemical action with the view of finding out the composition 
of a substance. In the etymological view of the matter, there is 
scarcely an operation performed either by the analyst or by the 
manufacturer but includes both analysis and synthesis — that is, 
includes interchange, or metathesis. 

Lime-kilns. — On the large scale the above operation is carried on 
in what are termed lime-kilns (Kiln, Saxon, cyln, from cylene, a 
furnace). 

Hydrate of Calcium (Slaked Lime). 

Slaked Lime. — When cold, add to the lime about half its 
weight of water, and notice the evolution of steam and other 
evidence of strong action; the product is slakedlime or hydrate 
of calcium (Ca2HO), with whatever slight natural impurities 
the lime may contain. The slaking of hard or " stony " lime 
may be accelerated by using hot water. 

CaO + H 2 = Ca2HO 

Lime. Water. Etydrate of calcium 

Lime-water. — Place the hydrate of calcium (washed with a 
little water to remove traces of soluble salts) in about a 
hundred times its weight of water ; in a short time a satu- 
rated solution, known as lime-water (Liquor Calais, TJ. S. P.), 
results. It contains about 0.15 per cent of slaked lime, or 
about 16 grains of hydrate of calcium (Ca2HO), equivalent 
to about 11 or 12 grains of lime (CaO), in one (Imperial) pint 
at 60° F., at higher temperatures less is dissolved. Sp. gr. 
1.0015. 

Strong Solution of Lime. — Slaked lime is more soluble in aqueous 
solution of glycerin and much more soluble in aqueous solution of 
sugar than in pure water. The Syrupus Calcis, U. S. P., is such a 
solution, containing 5 parts of lime and 30 of sugar in 100 parts, by 
weight, of fluid. 

Solutions of hydrate of calcium absorb carbonic acid gas on ex- 
posure to air, a semi-crystalline precipitate of carbonate being de- 
posited. When the saccharated solution is heated, there is precipi- 
tated a compound consisting of three molecules of lime with one of 
sugar. When it is freely exposed to air, oxygen is absorbed and the 
solution becomes colored. 

Carbonate of Calcium. 
Third Synthetical Reaction. — To a solution of chloride of 
calcium add excess of carbonate of sodium, or about 5 parts 



CALCIUM. 107 

of dry chloride to 13 of carbonate ; a white precipitate of car- 
bonate of calcium (Calcii Carbonas Prsecipitatus, U. S. P.) 
(CaC0 3 ) results. If the solutions of the salts be made hot 
before admixture, and the whole set aside for a short time, the 
particles aggregate to a greater extent than when cold water 
is used, and the product is finely granular or slightly crystal- 
line. 

CaCl 2 + Na 2 C0 3 = CaCO s + 2NaCl 

Chloride of Carbonate of Carbonate of Chloride of 

calcium. sodium. calcium. sodium. 

Collect and purify this Precipitated Chalk by pouring the 
mixture into a paper cone supported by a funnel, and, when 
the liquid has passed through the filter, pour water over the 
precipitate three or four times until the whole of the chloride 
of sodium is washed away. This operation is termed washing 
a precipitate. When dried by aid of a water-bath (p. 110) or 
other means, the precipitate is fit for use. 

Filtering-paper, or bibulous-paper (from bibo, to drink), is simply 
good unsized paper made from the best white rags — white blotting- 
paper, in fact, of unusually good quality. Students' or analysts' 

Fig. 22. 



Construction of Paper Filters. 

filters, on which to collect precipitates, are circular pieces (a) of this 
paper, from three to six inches in diameter, twice folded (6, c), and 
then opened out so as to form a lollow cone (d). Square pieces of 
filter paper are rounded by scissors after twice folding. The cone is 
supported by a glass or earthenware funnel. 

Filters should always be cut round so as to form a cone. If the 
square piece of paper is folded and used without being so cut or 
trimmed, an ugly angular filter results, from which it is difficult to 
wash all "mother-liquor" (the solution of chloride of sodium is the 
"mother-liquor" in the previous reaction). Moreover, if a spirit- 
uous or other volatile liquor is being passed through such an angu- 
lar filter, much of the liquid will also be wasted by evaporation from 
the unnecessarily large surface exposed. 

Paper filters of large size are apt to break at the point of the cone. 
This may be prevented, and the rate of filtration be much accelerated, 
by supporting the paper cone in a cone of muslin. 

Washing-bottle. — Precipitates are best washed by a line jet o( 
water directed on to the different parts of the filter. A common 
narrow-necked bottle of about half-pint capacity (Fig, 23) is fitted 






108 THE METALLIC RADICALS. 

with a cork ; two holes are bored through the cork, the one for a 
glass tube reaching to the bottom of the bottle within, and exter- 
nally bent to a slightly acute angle, the other for a tube bent to a 
slightly obtuse angle, the inner arm terminating just within the 
bottle. The outer arms may be about 3 inches in length. The ex- 
tremity of the outer arm continuous with the long tube should be 
previously drawn out to a fine capillary opening by holding the 
original tube, before cutting, in a flame, and, when soft, slowly pull- 
ing the halves away from each other until the heated portion is re- 
duced to the thinness of a knitting-needle. The tube is now cut at 
the thin part by a file, and the sharp edges rounded off by placing in 

Fig. 23. Fig. 24. 





Washiug-bottles. 

a flame for a second or two. The outer extremity of the shorter tube 
should also be made smooth in the flame. The apparatus being put 
together, and the bottle nearly filled with water, air, blown through 
the short tube by the lungs, forces water out in a fine stream at the 
capillary orifice. 

For a Jwt-ivater washing flask (Fig. 24) the tubes and cork are 
fitted to a flask which may be heated. A strip of leather tied 
round the neck will protect the fingers. 

Decantation. — Precipitates may also be washed by allowing them 
to settle, pouring off the supernatant liquid (Fig. 25), agitating with 
water, again allowing to settle, and so on. This is washing by de- 
cantation (de, from, canthus, an edge). If a stream of liquid flow- 
ing from a basin or other vessel exhibits any tendency to run down 
the outer side of the vessel, it should be guided by a glass rod placed 
against the point whence the stream emerges (Fig. 26). 

If the vessel be too large to handle with convenience, the wash 
water may be drawn off by a siphon, as shown in miniature in Fig. 
27. A siphon is a tube of glass, metal, gutta-percha, or India-rub- 
ber bent into the form of a V or U, filled with water, and inverted; 
one end immersed in the wash-water, and the other allowed to hang 
over the side of the vessel. So long as the outer orifice of the instru- 
ment is below the level of any liquid in the vessel, so long will that 
liquid flow from within outwards.* 

* The nature of the action of a siphon is simple. The column of water 
in the outer limb is longer, and therefore heavier than the column of 



Fig. 25. 



Fig. 27. 




109 



Decantation. 



Siphon in action. 



Prepared carbonate of calcium {Creta Prceparata, U. S. P.) is 
merely washed chalk or whiting, only that in pharmacy fashion 
demands that the chalk be in little conical lumps, about the size of 
thimbles, instead of the larger rolls characteristic of " whiting." 
Wet whiting pushed, portion by portion, through a funnel, and each 
separately dried, gives the conventional Creta Prceparata. Its powder 
is amorphous. If either the precipitated or prepared carbonate of 
calcium contains alumina, magnesian salts, oxide of iron, or phos- 
phates, its solution in acid, evaporated and redissolved in water, will 
yield a precipitate of hydrates or phosphates on addition of saccha- 
rated solution of lime. 

Testa Prceparata is powdered oyster-shell, similarly treated. It 
^is an inferior kind of prepared chalk. 

Phosphate of Calcium. 

Fourth Synthetical Reaction. — Digest bone-ash (bones burnt 
in an open crucible with free access of air until all animal and 
carbonaceous matter has been removed — impure phosphate of 
calcium (Os Usfum, B. P.)) with twice its weight of hydro- 
chloric acid diluted with four times its bulk of water), in a 
test-tube or larger vessel ; the phosphate is dissolved. 
Ca s 2P0 4 + 4HC1 = CaH 4 2PQ 4 + 20a CI,, 

Phosphate of Hydrochloric Acid phosphate Chloride of 

calcium (impure). acid. of calcium. calcium. 



similar area in the inner limb. (The length of the inner limb must 
be reckoned from the surface of the liquid, the portion below the sur- 
face playing no part in the operation.) Being heavier, it naturally 
falls by gravitation, the liquor in the shorter limb instantly following. 
because pressed upwards by the air. The air, be it observed, exerts a 
similar amount of pressure on the liquid in the outer limb: in short, 
atmospheric pressure causes the retention of liquid in the instrument, 
while gravitation determines the direction of the How. 



110 THE METALLIC RADICALS. 

Dilute with water, filter, boil, and when cold add excess of 
solution of ammonia ; the phosphate of calcium, now pure 
{Calcii ' Phosphas Prsecipitatus, U. S. P.), is reprecipitated as a 
light white amorphous powder. After well washing the pre- 
cipitate should be dried over a water-bath (see below), or at a 
temperature not exceeding 212°, to prevent undue aggregation 
of the particles. 

CaH 4 2P0 4 + 2CaCl 2 + 4NH 4 HO = Ca 3 2P0 4 + 4NH 4 C1 

Acid phosphate Chloride Ammonia. Phosphate of Chloride of 

of calcium. of calcium. calcium (pure). ammonium. 

+ 4H 2 

Water. 

Bone-ash or bone-earth contains small quantities of carbonate 
and sulphide of calcium. These are decomposed in the above 
process by the acid, chloride of calcium being formed ; on boil- 
ing the mixture, carbonic acid gas and sulphuretted hydrogen 
gas are evolved. Any carbonaceous or siliceous matter, etc. 
is removed by filtration. In bones the phosphate of calcium is 
always accompanied by a small quantity of an allied substance, 
phosphate of magnesium ; a trace of fluoride of calcium (CaF 2 ) 
is also present. 

A Water-bath for the evaporation of liquids or for drying 
moist solids at temperatures below 212° F. is an iron, tin, or 
earthenware pan, the mouth of which can be narrowed by iron 
or tin diaphragms of various sizes, and having orifices adapted 
to the diameters of evaporating dishes or plates. In the British 
Pharmacopoeia, " when a water-bath is directed to be used, it 
is to be understood that this term refers to an apparatus by 
means of which water or its vapor, at a temperature not ex- 
ceeding 212°, is applied to the outer surface of a vessel con- 
taining the substance to be heated, which substance may thus 
be subjected to a heat near to, but necessarily below, that of 
212°. In the steam-bath the vapor of water at a temperature 
above 212°, but not exceeding 230°, is similarly applied." 
Evaporation in vacuo is performed by simply placing the vessel 
of liquid over or by the side of a small reservoir of strong sul- 
phuric acid, or other absorbent of moisture, on the plate of an 
air-pump, covering with a capacious glass hood or " receiver," 
and exhausting. 

Bone-black, or Animal Charcoal ( Carbo Animalk, U. S. P.), 
is the residue obtained on subjecting dried bones to a red heat 
without access of air. It is a mixture of about 9 parts of min- 
eral matter with 1 of carbonaceous matter. The operation may 
be imitated by heating a few fragments of bone in a covered 



CALCIUM. Ill 

porcelain crucible in a fume chamber until smoke and vapor 
cease to be evolved. Purified Animal Charcoal (Carbo Ani- 
malis Purificatus, U. S. P.) is obtained by digesting animal 
charcoal (2 parts) in hydrochloric acid (3 parts) and water (30 
parts) in a warm place for a day or so, filtering, thoroughly 
washing, drying over a water-bath, and igniting the product in 
a closely covered crucible. The reaction is the same as that 
just described ; that is to say, the acid removes the phosphate 
of calcium from the carbon of animal charcoal by forming 
soluble acid phosphate and chloride of calcium. The residual 
charcoal, if well washed, will not yield more than about 2 per 
cent, of calcareous matter when burnt with free access of air 
or with the aid of the oxygen of a little red oxide of mercury. 

Wood Charcoal ( Carbo Ligni, U. S. P.) is wood similarly 
ignited without access of air. 

Decolorizing Power of Animal Charcoal. — Animal charcoal, 
in small fragments, is the material employed in decolorizing 
solutions of common brown sugar with the view of producing 
white lump sugar. Its power and the nearly equal power of 
an equivalent quantity of the purified variety may be demon- 
strated on solution of litmus or logwood. 

Syrupus Calcii Lacto-phosphatis, U. S. P., is a flavored solu- 
tion of precipitated phosphate of calcium in lactic acid. 

Phosphate of Sodium. — Phosphate of calcium is converted 
into phosphate of sodium (Sodii Photphas, U. S. P.) (Na 2 HP0 4 , 
12H 2 0) as follows : Mix, in a mortar, 3 ounces of ground bone- 
earth with one fluidounce of sulphuric acid ; set aside for 
twenty-four hours to promote reaction ; mix in about 3 ounces 
of water, and put in a warm place for two days, a little water 
being added to make up for that lost by evaporation ; stir in 
another 3 ounces of water, warm the whole for a short time, 
filter, and wash the residual sulphate of calcium on the filter 
to remove adhering acid phosphate of calcium ; concentrate the 
filtrate (the liquid portion), which is a solution of acid phos- 
phate of calcium, to about 3 ounces, filter again, if necessary, 
add solution of (about 4^ ounces of crystals of) carbonate of 
sodium to the hot filtrate until a precipitate (a phosphate of 
calcium, CaHP0 4 ) ceases to form, and the fluid is faintly alka- 
line ; filter, evaporate, and set aside to crystallize. 

Phosphate of sodium occurs "in transparent colorless rhom- 
bic prisms, terminated by four converging planes, efflorescent, 
tasting like common salt." One part to ten of water constitutes 
"Solution of Phosphate of Sodium," B. P. The following 
equations show the two decompositions which occur during 
the operation : — 



112 THE METALLIC RADICALS. 

Ca 3 2P0 4 + 2H 2 S0 4 = CaH 4 2P0 4 + 2CaS0 4 

Phosphate Sulphuric Acid phosphate Sulphate of 

of calcium. acid. of calcium. calcium. 

CaH 4 2P0 4 + Na 2 C0 3 = Na 2 HP0 4 + H 2 

Acid phosphate Carbonate Phosphate of "Water. 

of calcium. of sodium. sodium. 

+ C0 2 + CaHPO, 



Ordinary phosphate of sodium (Na 2 HP0 4 ,12H 2 0) effloresces 
rapidly in the air until nearly half its water has escaped, when 
it has a permanent composition represented by the formula 
Na 2 HP0 4 ,7H 2 0. Phosphate of sodium has an alkaline reac- 
tion ; neutralization by acid results in the removal of half its 
sodium and formation of the salt NaH 2 P0 4 ,H 2 0. 

Hypochlorite of Calcium. 

Fifth Synthetical Reaction. — Pass chlorine, generated as 
already described, into damp slaked lime contained in a piece 
of wide tubing, open at the opposite end to that in which the 
delivery-tube is fixed. (A test-tube, the bottom of which has 
been accidentally broken, is very convenient for such opera- 
tions.) The product is ordinary bleaching-powder, a compound 
of hypochlorite and chloride of calcium, commonly called chlo- 
ride of lime (Calx Chlorata, U. S. P.). 

Mn0 2 + 4HC1 = MnCl 2 + 2H 2 + CI, 

Black oxide Hydrochloric Chloride of Water. Chlorine, 

of manganese. acid. manganese. 

2CaH 2 2 + 2CL = 2H 2 + CaCl 2 2 , CaCl 2 

Hydrate of Chlorine. Water. Hypochlorite of Chloride 

calcium. of calcium. of calcium. 

Chlorinated lime, exposed to air and moisture, as in disinfecting 
the air of sick-rooms, slowly yields hypochlorous acid (HCIO). Free 
hypochlorous acid soon breaks up into water, chloric acid (HC10 3 ), 
and free chlorine. Chloric acid is also unstable, decomposing into 
oxygen, water, chlorine, and perchloric acid (HC10J. The small 
quantity of hypochlorous acid diffused through an apartment when 
bleaching-powder is exposed thus, yields fourteen-fifteenths of its 
chlorine in the form of chlorine gas — one of the most efficient of 
known disinfectants. 

Constitution of Bleaching-powder. — Treated with alcohol, 
bleaching-powder does not yield its chloride of calcium to the 
solvent, hence the powder is not a mere mixture of chloride 
and hypochlorite of calcium : water, also, does not dissolve out 
first one salt, and then the other, but both together, in the 
molecular proportions of the above formula. On the other 



CALCIUM. 113 

hand, when the aqueous solution is cooled, or evaporated in 
vacuo, crystals are obtained which Kingzett has shown to be 
nearly pure hypochlorite of calcium, the solution containing 
chloride of calcium. While the former fact indicates that the 
powder is a compound, and not a mere mixture, the latter in- 
dicates that it is a feeble compound ; an adhesion of molecules 
of hypochlorite and chloride, as shown in the equation, rather 
than any more intimate or closer combination of atoms. If 
it be regarded as a single rather than a double salt, then the 

following formula may be employed, CaOCl 2 or Ca ■< ™q 

Blenching -liquor. — Digest chlorinated lime in water, in which 
the bleaching compound is soluble, filter from the undissolved 
lime, and test the bleaching powers of the clear liquid by add- 
ing a few drops to a decoction of logwood slightly acidulated. 
One pound of this bleaching-powder, shaken several times 
during three hours with 1 gallon of water, forms Solution of 
Chlorinated Lime (Liquor Calcis Chlorinate, B. P.). 

Sixth Synthetical Reaction. — Heat a mixture of 10 parts of 
powdered lime and 9 of sulphur in a crucible having a luted 
cover for an hour. The product, when cold, rubbed to powder, 
constitutes Sulphurated Lime (Calx Sulphurata, U. S. P.). 
It should contain not less than 36 per cent, of sulphide of 
calcium (CaS) ; the remainder is sulphate, with, probably, sul- 
phite and hyposulphite of calcium. 

Gummate of Calcium. 

Gummate of Calcium is the only official calcium salt that 
remains to be noticed. This compound is, in short, a rah ft), 
the ordinary Grum Acacia, or Gum Arabic (Acacia, U. S. P.), 
a substance too well known to need description. A solution 
of gum arabic in water (Mucilago Acacise, U. S. P.) yields a 
white precipitate of oxalate of calcium on the addition of solu- 
tion of oxalate of ammonium. Or a piece of gum burnt to an 
ash in a porcelain crucible yields a calcareous residue, which, 
dissolved in dilute acids, affords characteristic reactions with 
any of the following analytical reagents for calcium. In some 
specimens of gum arabic a portion of the calcium is displaced 
by an equivalent quantity of potassium or magnesium. The 
gummic or arabic radical may be precipitated as opaque gelat- 
inous gummate of lead by the addition of solution of oxy- 
acetate of lead (Liquor Plumbi Subacetat.is, U. S. P.) to an 
aqueous solution of gum. These statements may be experi- 
mentally verified by the practical student. 

10* 






114 THE METALLIC RADICALS. 



\ (lYagacantha, U. S. P.) is a mixture of soluble arabi- 
noid gum and a variety of calcium gum insoluble in water, termed 
bassorin. With water a gelatinous mucilage is formed {Mucilago 
Tragacanthce, U. S. P., contains 6 parts of tragacanth, 18 of gly- 
cerin, and 76 of water). 

Reactions having Analytical Interest (Tests). 

First Analytical Reaction. — Add sulphuric acid, very highly 
diluted, to a calcium solution contained in a test-tube or small 
test-glass ; sulphate of calcium (CaS0 4 ,2H 2 0) is formed, but 
is not precipitated, it being, unlike sulphate of barium, slightly 
soluble in water. 

Solution of Sulphate of Calcium. — A quarter of an ounce of that 
(dried) form of sulphate of calcium known as plaster of Paris (CaSOJ 
digested in one pint of water for a short time, with occasional shak- 
ing, and the mixture filtered, yields the official test-liquid termed 
" Solution of Sulphate of Calcium,'' B. P. About 400 parts of the 
solution contain 1 of calcium. 

Second Analytical Reaction. — Add yellow chromate of potas- 
sium (K 2 Cr0 4 ) or other neutral chromate (KNH 4 Cr0 4 ), to a 
calcium solution slightly acidified with acetic acid ; chromate 
of calcium (CaCr0 4 ) is probably formed, but it is not precipi- 
tated. Barium is precipitated by the chromic radical. 

These two negative reactions are most valuable in analysis, as 
every precipitant of calcium is also a precipitant of barium ; but 
the above two reagents are precipitants of barium only. Hence 
calcium, which when alone can be readily detected by the following 
reactions, cannot by any reaction be detected in the presence of 
barium. But by the sulphuric or chromic test barium is easily 
removed, and then either of the following reagents will throw down 
the calcium. 

Other Analytical Reactions. — Add carbonate of ammonium, 
phosphate of sodium, arseniate of ammonium, and oxalate of 
ammonium to calcium solutions as described under the ana- 
lytical reactions of barium, and write out descriptive equations. 
The precipitates correspond in appearance to those of barium ; 
their constitution is also similar, hence their correct formulae 
can easily be decFuced. Of these precipitants oxalate of am- 
monium is that most commonly used as a reagent for calcium 
salts, barium being absent. The oxalate of calcium is insoluble 
in acetic, but soluble in hydrochloric or nitric acid. Cal- 
cium compounds impart a reddish color to the flame. 



CALCIUM. 115 



QUESTIONS AND EXERCISES. 

143. Enumerate some of the common neutral compounds of cal- 
cium. 

144. Explain, by an equation, the action of hydrochloric acid on 
marble. AVhat official compounds result? 

145. Why is chloride of calcium used as a desiccator for gases ? 

146. How would you purify Chloride of Calcium which has been 
made from ferruginous marble ? Give diagrams. 

147. Write a few lines on the chemistry of the lime-kiln. 

148. In what sense is the conversion of chalk into lime an analyt- 
ical action ? 

149. What occurs when lime is " slaked " ? 

150. To what extent is lime soluble in water? to what in syrup? 

151. Describe the preparation of the official Precipitate of Carbo- 
nate of Calcium •, in what does it differ from Prepared Chalk ? 

152. In what does filtering-paper differ from other kinds of paper ? 

153. Explain the construction of "a washing-bottle" for cleans- 
ing precipitates by water. 

154. Describe decantation. 

155. Describe the construction and manner of employment of a 
siphon. 

156. Explain the mode of action of a siphon. 

157. What is the difference between Bone, Bone-earth, and Pre- 
cipitated Phosphate of Calcium ? 

158. How is "Bone-earth" purified for use in medicine? 

159. Explain the action of hydrochloric acid on Animal Char- 
coal in the conversion of Carbo Animalis into Carbo Animal is 
Purijicatus. 

160. What is the chemical difference between Carbo Animalis 
and Carbo Ligni? 

161. Give equations showing the conversion of Phosphate of Cal- 
cium into Phosphate of Sodium. 

162. Write a short article on the manufacture, composition, and 
uses of " bleaching-powder." 

163. How may calcium be detected in Gum Arabic ? 

164. State the chemical nature of Tragacanth. 

165. To what extent is sulphate of calcium soluble in water? 

166. Can calcium be precipitated from an aqueous solution con- 
taining barium? 

167. Barium being absent, what reagents may be used for the 
detection of calcium? Which is the chief test? 



116 THE METALLIC RADICALS. 

MAGNESIUM. 

Symbol Mg. Atomic weight 24. 

Source. — Magnesium is abundant in nature in the form of niagne- 
sian or mountain limestone, or dolomite, a double carbonate of mag- 
nesium and calcium in common use as a building-stone (e. g., the 
Houses of Parliament and the School of Mines in London), and 
magnesite, a tolerably pure carbonate of magnesium, though too 
"stony" for direct use in medicine, even if very finely powdered. 
Chloride of magnesium and sulphate of magnesium (Epsom salt) 
also occur in sea-water and in the water of many springs. A mono- 
hydrous sulphate (MgS0 4 ,H 2 0) termed kieserite occurs near Stass- 
furt in Prussia. Metallic magnesium may be obtained from the 
chloride by the action of sodium. It burns readily in the air, 
emitting a dazzling light, due to the white heat to which the result- 
ing particles of magnesia (MgO) are exposed. The chloride em- 
ployed as a source of the metal is obtained by dissolving the car- 
bonate in hydrochloric acid, adding some chloride of ammonium, 
evaporating to dryness, heating the residue in a flask (on the small 
scale a large test-tube or Florence flask) until the chloride of am- 
monium is all volatilized and the chloride of magnesium remains as 
a clear fused liquid. The latter is poured on to a clean earthenware 
slab. The chloride of ammonium prevents reaction between chlo- 
ride of magnesium and water in the last stages of the operation and 
consequent formation of oxide (or oxychloride) of magnesium and 
hydrochloric acid gas. 

Quantivalence. — The atom of magnesium is bivalent, Mg". 

Reactions having Synthetical Interest. 

Sulphate of Magnesium. 

First Synthetical Reaction. — To a few drops of sulphuric 
acid and a little water in a test-tube, made hot (or to larger 
quantities in larger vessels), add powdered native carbonate of 
magnesium, magnesite, MgC0 3 , until effervescence ceases, sub- 
sequently boiling to aid in the expulsion of the carbonic acid 
gas. The filtered liquid is a solution of sulphate of magnesium 
(MgS0 4 ), crystals of which, Epsom salt (MgS0 4 ,7H 2 0) (Mag- 
netic Sulphas, U. S. P.), may be obtained on evaporating most 
of the water and setting the concentrated solution aside to 
cool. This is an ordinary manufacturing process. Instead of 
magnesite, dolomite, the common magnesian limestone (carbo- 
nate of magnesium and calcium, CaC0 3 ,MgC0 3 ), may be em- 
ployed, any iron being removed by evaporating the solution 
(filtered from the sulphate of calcium produced) to dryness, 
gently igniting to decompose sulphate of iron, dissolving in 
water, filtering from oxide of iron, and crystallizing. (If 
neither mineral be at hand, the practical student may use a 



MAGNESIUM. 117 

little of the ordinary manufactured carbonate of pharmacy, 
for the chemical action is almost identical, and it is the chem- 
istry and not, just now, the commercial economy of the matter 
that he is studying. The manufacturer must, of course, com- 
mence with one of the above mineral carbonates furnished by 
nature, from that make his sulphate, and from the latter, as 
will be seen directly, make the pure pulverulent carbonate of 
pharmacy.) 

MgCO, + H 2 S0 4 = MgS0 4 + H 2 + CO, 

Carbonate of Sulphuric Sulphate of Water. Carbonic 

magnesium. acid. magnesium. acid gas. 

Sulphate of magnesium readily crystallizes in large, colorless, 
transparent, rhombic prisms ; but, from concentrated solutions, the 
crystals are deposited in short thin needles, a form more convenient 
for manipulation, solution, and general use in medicine. 

Iron may be detected in sulphate of magnesium by adding the 
common alkaline solution of chlorinated lime or chlorinated soda to 
some aqueous solution of the salt •, brown hydrate of iron (Fe 2 6HO) 
is then precipitated. Sulphydrate ammonium will also give a black 
precipitate if iron be present. 

Carbonates of Magnesium. 

Second Synthetical Reaction. — To solution of sulphate of 
magnesium add solution of carbonate of sodium, and boil ; the 
resulting precipitate is light carbonate of magnesium (Magnesise 
Carbonas Levis, B. P. ; Magnesii Carbonas, U. S. P.), the old 
light carbonate of magnesia, a white, partly amorphous, partly 
minutely crystalline mixture of carbonate and hydrate of mag- 
nesium (3MgC0 3 ,Mg2HO,4H 2 0, B. P. ; 4MgC0 3 ,Mg2HO,- 
5H. 2 0, U. S. P.). A denser, slightly granular precipitate of 
similar chemical composition (Magnesise Carbonas, B. P.), the 
old heavy carbonate of magnesia, is obtained on mixing strong 
solutions of the above salts, evaporating to dryness, then re- 
moving the sulphate of sodium by digesting the residue in hot 
water, filtering, washing, and drying the precipitate. 

4MgS0 4 + 4Na,CO, -f H a O = 

Sulphate of magnesium. Carbonate of sodium. Water. 

3MgC0 3 ,Mg2HO + 4Na 2 S0 4 -f CO, 

Official carbonate of magnesium. Sulphate of sodium. Carbonic arid gas. 

The official (B. P.) proportions for the light carbonate are 10 of 
sulphate of magnesium and 12 of crystals of carbonate o^ sodium, 
each dissolved in 80 of cold water, the solutions mixed, boiled for 15 
minutes, the precipitate collected on a filter, well washed, drained, 
and dried over a water-hath. The heavier carbonate is made with 
the same proportions of salts, each dissolved in 20 instead o[' 80 oi' 



118 THE METALLIC RADICALS. 

water, the mixture evaporated quite to dryness, and the residue 
washed by decantation or nitration until all sulphate of sodium is 
removed (shown by a white precipitate — sulphate of barium — ceas- 
ing to form on the addition of solution of chloride or nitrate of 
barium to a little of the nitrate). 

Another (Patthison's) Process. — Considerable quantities of 
carbonate of magnesium are now prepared by treating dolomite 
(see p. 115) with carbonic acid under pressure. Of the two 
carbonates the magnesian is dissolved first, and is precipitated 
from the clear liquid by the heat of a current of steam. (See 
next reaction.) 

Tli trd Synthetical Reaction. — Pass carbonic acid gas, gene- 
rated as described on page 71. into a mixture of water and car- 
bonate of magnesium contained in a test-tube. After some time, 
separate undissolved carbonate by filtration ; the filtrate contains 
normal carbonate of magnesium (MgC0 3 3H 2 0) dissolved by car- 
bonic acid. When of a strength of about 10 grains of official car- 
bonate in one ounce, such a solution constitutes u Fluid Magnesia " 
(Liquor JIagneside Carbonatis, B. P.). It is impossible to obtain 
a strength of over 3 per cent, at about 55° F. is reduced to 2 J 
per cent, at 70° and to about 2 per cent, at 80° F. 

Officially. 1 pint is directed to be made from freshly prepared car- 
bonate. The latter is obtained by adding a hot solution of 2 ounces 
of sulphate of magnesium in half a pint of water to one of 2J ounces 
of crystals of carbonate of sodium in another half pint of water, 
boiling the mixture for a short time (to complete decomposition), 
filtering, thoroughly washing the precipitate, placing the latter in 
1 pint of distilled water, and transmitting carbonate acid gas 
through the liquid (say. at the rate of three or four bubbles per 
second) for an hour or two, then leaving the solution in contact 
with the gas under pressure of about 3 atmospheres for twenty-four 
hours, and, finally, filtering from undissolved carbonate, and, after 
passing in a little more gas, keeping in a well-corked bottle. Slight 
pressure is best produced by placing the carbonate and water in a 
bottle fitted with a cork and tubes as for a wash-bottle (p. 97 or 108), 
conveying the gas by the tube which reaches to the bottom, and allow- 
ing excess of gas to flow Out by the upper tube, the external end of 
which is continued to the bottom of a common phial containing about 
an inch of mercury. The phial should be loosely plugged with cot- 
ton-wool, to prevent loss of metal by spurting during the flow of the 
<ras through it. (Each inch in depth of mercury through which 
the gas escapes corresponds to about half a pound pressure on 
every square inch of surface within the apparatus.) 

Heat a portion of the solution : true carbonate of magnesium con- 
taining combined water (MgC0 3 ,3H 2 0) is precipitated. The water 
in this compound is probably in the state of water of crystallization, 
for a salt having the same composition is deposited in crystals by the 



MAGNESIUM. 119 

spontaneous evaporation of the solution of carbonate of magnesium. 
The official "carbonate" (3MgC0 3 .Mg2HO,4II 2 0) is another of these 
very common hydrous compounds. 

Exposed to cold, the solution of "fluid magnesia" sometimes 
affords large thick crystals (MgC0 3 ,5H 2 0), which, in contact with 
the air, lose water, become opaque, and then have the composition 
of those deposited by evaporation (MgC0 3 ,3H 2 0). 

Oxide of Magnesium (Magnesia). 

Fourth Synthetical Reaction. — Heat light dry carbonate of 
magnesium in a porcelain crucible over a lamp (or in a larger 
earthen crucible in a furnace) till it ceases to effervesce on add- 
ing, to a small portion, water and acid ; the residue is light 
magnesia (MgO) (Magnesia Levis, B. P. ; Magnesia, U. S. P.). 
The same operation on the heavy carbonate yields heavy mag- 
nesia (MgO) {Magnesia Ponderosa, U. S. P.). Both are some- 
times spoken of as " calcined magnesia." A given weight of 
the official light magnesia occupies three and a half times the 
bulk of the weight of heavy magnesia. 

3MgC0 3 ,Mg2HO = 4MgO -f H 2 + 3CO a 

Official carbonate of Oxide of Water. Carbonic 

magnesium. magnesium. acid gas. 

A trace only of magnesia is dissolved by water. Moisten a 
grain or two of magnesia with water, and place the paste on a 
piece of- red litmus-paper ; the wet spot, after a time, becomes 
blue, showing that the magnesia is slightly soluble. 

" Effervescing Citrate of Magnesia" so called, is generally 
a mixture of bicarbonate of sodium, citric acid, tartaric acid, 
sugar, either carbonate or sulphate of magnesium, or both, and 
flavoring essences. True citrate of magnesium is easily made 
by heating together calcined magnesia and citric acid ; it is 
frequently prescribed in France in doses of two ounces. 

The official "Granulated Citrate of Magnesium" (Magnesii 
Cifras Granulatus, U. S. P.) is made as follows : Mix 11 parts 
of carbonate of magnesium intimately with 33 of citric acid. 
and enough distilled water to make a thick paste ; dry this at 
a temperature not exceeding 30° C (86° F.), and reduce it to 
a fine powder. Then mix it intimately with 8 of sugar (No. 
60 powder), 37 of bicarbonate of sodium, and 15 of citric acid 
previously reduced to a very fine powder. Dampen the mass 
with a sufficient quantity of alcohol, and rub it through a No, 
20 tinned-iron sieve, to form a coarse, granular powder. Lastly, 
dry it in a moderately warm place. 

The official Effervescing "Solution of Citrate of Magne- 
sium" (Liquor Magucsii Citrati$ : U. S. P.) is made by dissolv- 



120 THE METALLIC RADICALS. 

ing carbonate of magnesium in slight excess of solution of 
citric acid, adding syrup of citric acid, placing the diluted 
liquid in an aerated-water bottle, dropping in crystals of bicar- 
bonate of potassium, corking, " wiring," and snaking till the 
crystals are dissolved. 

The formula of citrate of magnesium deposited from solu- 
tion is Mg 3 2C 6 H 5 7 ,14H 2 0. 

Reactions having Analytical Interest (Tests). 

First Analytical Reaction. — Add solution of hydrate or car- 
bonate of ammonium to a magnesian solution (sulphate, for ex- 
ample) and warm the mixture in a test-tube ; the precipitation 
of part only of the magnesium as hydrate (Mg2HO) or car- 
bonate (MgC0 3 ) occurs. Add now to a small portion of the 
mixture of precipitate and liquid a considerable excess of solu- 
tion of chloride of ammonium ; the precipitate is dissolved. 

This is an important reaction, especially as regards carbonate of 
magnesium, the presence of chloride of ammonium enabling the ana- 
lyst to throw out from a solution barium and calcium by an alkaline 
carbonate, magnesium being retained. The cause of this retention is 
found in the tendency of magnesium to form soluble double salts with 
potassium, sodium, or ammonium. In analysis, the chloride of am- 
monium should be added before tjie carbonate, as it is easier to pre- 
vent precipitation than to redissolve a precipitate once formed. 

Second Analytical Reaction. — To some of the solution re- 
sulting from the last reaction, add solution of phosphate of 
sodium or ammonium ; phosphate of magnesium and ammo- 
nium (MgNH 4 P0 4 ) is precipitated. 3d. To another portion 

add arseniate of ammonium ; arseniate of magnesium and 
ammonium (MgNH 4 As0 4 ) is precipitated. 

Note. — Barium and calcium are also precipitated by alkaline phos- 
phates and arseniates. The other precipitants of magnesium are 
also precipitants of barium and calcium. In other words, there is 
no direct test for magnesium. Hence the analyst always removes 
any barium. or calcium by an alkaline carbonate, as above indicated 5 
the phosphate of sodium, or arseniate or phosphate of ammonium, 
then becomes a very delicate test of the presence of magnesium. In 
speaking of magnesium tests, the absence of barium and calcium 
salts is to be understood. 



QUESTIONS AND EXERCISES. 

168. Name the natural sources of the various salts of magne- 



QUANTIVALENCE. 121 

1G9. Give a process for the preparation of Epsom salt. 

170. Draw diagrams illustrative of the formation of sulphate of 
magnesium from magnesite and from dolomite. 

171. Show by an equation the process for the preparation of the 
official Carbonate of Magnesium. 

172. What circumstances determine the two different states of 
aggregation of the Magnesia 3 , Carbonas and Magnesioz Carbonas 
Levis f 

173. What are the relations of Magnesia and Magnesia Levis to 
the British official Carbonates of Magnesium? 

174. How much denser is the one than the other? 

175. Is magnesia soluble in water? 

176. How is "Fluid Magnesia" prepared? 

177. Mention the effects of heat and cold on " Fluid Magnesia." 

178. How much magnesia (MgO) can be obtained from 100 grains 
of Epsom salt? 

179. Calculate the amount of official Carbonate of Magnesium 
which will yield 100 grains of magnesia. 

180. Can magnesium be detected in presence of barium and cal- 
cium? 

181. Describe the analysis of an aqueous liquid containing salts of 
barium, calcium, and magnesium. 

182. How may magnesium be precipitated from solutions contain- 
ing ammoniacal salts? 






On reviewing the foregoing statements regarding compounds of 
the three univalent radicals, potassium, sodium, and ammonium, and 
the three bivalent elements, barium, calcium, and magnesium, the 
doctrine of quantivalence will be more clearly understood, and its 
usefulness more apparent. Quantivalence, or the value of atoms, is, 
in short, in chemistry, closely allied to value in commercial barter. 
A number of articles, differing much in weight, appearance, and 
general characters, may be of equal money value ; and if these be 
regarded, for convenience, as having a sort of unit of value, others 
worth double as much might be termed bivalent, three times as much 
trivalent, and so on. In like manner, chemical radicals, no matter 
whether elementary, like potassium (K), iodine (1), or sulphur (S), 
or compound, like those of nitrates (NO.,), sulphates (S0 4 ), or ace- 
tates (C 2 H 3 2 ), have a given chemical value in relation to each other, 
and are exchangeable for, and will unite with, each other to an extent 
determined by that value. 

Most chemical salts apparently, though probably not really, have 
two parts, a basylous and acidulous, the one quantivalently balancing 
the other. The formulae of the chief of these radicals and their quan- 
tivalence are given on the following page. Examples of formulae of 
salts containing univalent, bivalent, and trivalent radicals arc also 
appended. 
11 



122 



THE METALLIC EADICALS. 



QUANTIVALENCE OF COMMON RADICALS. 



Univalent Radicals, 


Bivalent Radicals, 


Trivalent Radicals, 


or Monads. 


or 


Dyads. 


or Triads. 


Acidulous. 


Basylous. 


Acidulous. 


Basylous. 


Acidulous. Basylous. 


H 


II 





Ca 


P0 4 As 


CI 


K 


so 4 


Mg 


B0 3 Sb 


I 


Na 


co 3 


Zn 


C 6 H 5 7 Bi 


HO 


NH 4 


C 2 4 


Cu 


As0 3 f Fe Ui (ic) 
As0 4 \ or 
C 4 H 3 5 (Fe^(ic) 


N0 3 


Ag 


C 4 H 4 


Hg(ic) 


C 2 H 3 2 


Hg(ous) 


s 


Fe(ous) 



Note 1. — The hydrogen (H) in the basylous parts of salts has en- 
tirely different functions from the hydrogen (H) in the acidulous 
part. The latter gives compounds commonly termed hydrides (e. g., 
AsH 3 ) ; in the former the element is the basylous radical of acids 
(e. g., HC1, H 2 S0 4 ). In compound radicals (e.g., C 2 H 3 2 or XH 4 ) 
the properties of hydrogen are no longer apparent; the chemical 
force resident in the atoms of such radicals seems to be mainly 
exerted in binding those atoms together. 

Note 2. — The name, symbol, and quantivalence of all the import- 
ant elements are given in a Table immediately preceding the Index. 

Examples of Formula? of Salts containing Univalent, Bivalent, and 
Trivalent Radicals. 

The reader will find instructive practice in writing twenty or thirty 
imaginary formulae of salts by placing in juxtaposition acidulous and 
basylous radicals, as in the following table of examples. Just as in 
a pair of scales a 2-lb. weight must be balanced by two 1-lb. weights, 
or a 4-lb. weight by two 2-lb. weights, or by one 3-lb. and one 1-lb. 
weight, so a bivalent radical unites with a bivalent radical or with 
two univalent radicals, a quadrivalent radical with two bivalent radi- 
cals, or with one trivalent and one univalent radical, and so on. 

(R = any basylous Radical.) (i? = any acidulous Radical.) 
General formula. Examples. 

WR' KI. XaCl. XH 4 C. 7 H 3 9 , A 2 X0 3 . 

R"R' 2 .... CaCl 2 , Zn2C,H 3 0:„ Pb2X0 3 (BaX0 3 C 2 H 3 2 ). 

W'R' Z .... Bi3N0 3 , AsH 3 , SbCl 3 . 

W*R" . . \ ( K 2 C0 3 , Na,S0 4 , H 2 C 4 H 4 6 . 

W'R'R" . . } ( KHC0 8 , NaHS0 4 KXaC 4 H 4 6 . 

RV2'" . . ) Am 3 P0 4 , K 3 C 6 H 5 7 . H 3 As0 3 . 

W 2 WR'" . \ \ Xa„HP0 4 . Xa.JlAs0 4 . 

R"R" .... CaC0 3 ,MffO, CuSO., HgO, FeS0 4 . 

H'V?'", .... Ca 3 2P0 4< Ca 3 2C 6 H 5 7 - 

WR'R'" . . . MgAmPO,, CuHAs0 3 . 

W"R"R' . . . B1OXO3. 

W\R" % R.". . . Bi 2 2 C0 3 . 

R"\R" % - . . . As 2 3 , Sb 2 3 , Fe 2 3 , Fe 2 3S0.. 

R^R/" .... BiC fi il 5 0- 

Vf" % Bf % .... Fe 2 Cl 6 , Fe./»X0 3 . Fe./>C 2 H 3 2 . 



ALKALI AND ALKALINE EARTH METALS. 123 

Quadrivalent Radicals or Tetrads, Quinquivalent Radicals or Pen- 
tads, and Sexivalent Radicals or Hexads, are known. 



EXERCISE. 



183. Write an exposition of the doctrine of Quantivalence within 
the limits of a sheet of note paper. 






Directions for applying the foregoing analytical 

reactions to the analysis of an aqueous solution* 

of a salt of one of the metals, barium, calcium, 

Magnesium. 

Add yellow chromate of potassium to a portion of the solu- 
tion to be examined ; a precipitate indicates barium. 

If no barium is present, add chloride and carbonate of ammo- 
nium, and boil ; a precipitate indicates calcium. 

If barium and calcium are proved to be absent, add chloride 
of ammonium, ammonia, and then either phosphate of sodium 
or arseniate of ammonium ; a white granular precipitate indi- 
cates magnesium. 

Ammonia is here added to yield the necessary elements to ammo- 
nio-magnesian phosphate or ammonio-magnesian arseniate, both of 
which are highly characteristic precipitates ; and chloride of ammo- 
nium is added to prevent a mere partial precipitate of the magne- 
sium by the ammonia. 

Directions for applying the foregoing analytical 
reactions to the analysis of an aqueous solution 
of one, two, or all three of the metals, Ba- 
rium, Calcium, Magnesium. 

Add chromate of potassium to the solution ; barium, if pres- 
ent, is precipitated. Filter, if necessary, and add to the fil- 
trate (that is, the liquid which has run through the filter) chlo- 
ride, hydrate, and carbonate of ammonium, and boil ; calcium, 
if present, is precipitated. Filter, if requisite, and add phos- 
phate of sodium ; magnesium, if present, is precipitated. 

Note. — Red chromate of potassium must not be used in these op- 
erations, or a portion of the barium will remain in the liquid and be 
thrown down with, or in place of, the carbonate of calcium (vide p. 
103). The yellow chromate must not contain carbonate of potas- 
sium, or calcium will be precipitated with, or in place oi\ barium. 

* In preparing such solutions for analysis, salts should be selected 
which do not decompose each other. Chlorides will serve in most 
cases, but nitrates and acetates are still more convenient, 



124 



THE METALLIC RADICALS. 



The absence of carbonate is proved by the non-occurrence of 
effervescence on the addition of hydrochloric acid to a little of the 
solution of the chromate, previously made hot in a test-tube. If 
the yellow chromate has been prepared by adding excess of ammo- 
nia to solution of red chromate of potassium, its addition to the 
liquid to be analyzed must be preceded by that of solution of chlo- 
ride of ammonium, the precipitation of a portion of the magnesium 
(by the free ammonia in the yellow chromate) is thus prevented, for 
chloride of ammonium solution is a good solvent of hydrate (and 
carbonate) of magnesium, as already stated on page 120. 

Note 1. — The analysis of solutions containing the foregoing met- 
als is commenced by the addition of chloride of ammonium (XH 4 C1) 
and ammonia (XII 4 HO), simply as a precautionary measure, the for- 
mer compound preventing partial precipitation of magnesium, the 
latter neutralizing acids. The carbonate of ammonium (XH,) 2 C0 3 is 
the important group reagent — the precipitant of barium and calcium. 

Note 2. — In the following, and in subsequent charts of analytical 
processes, the leading preeipitants will be found to be ammonium 
salts. These, being volatile, can be got rid of towards the end of 
the operations, and thus the detection of potassium and sodium be 
in no way prevented — an advantage which could not be had if such 
salts as chromate of potassium or phosphate of sodium were the 
group-precipitants employed. 

Note 3. — Acetic, and not hydrochloric or nitric, acid is used in 
dissolving the barium and calcium carbonates, because chromate of 
barium, on the precipitation of which the detection of barium de- 
pends, is soluble in the stronger acids, and therefore could not be 
thrown down in their presence. 

Table of short directions for applying the foregoing 
analytical reactions to the analysis of an aqueous 
solution of salts containing any or all of the 
metallic elements hitherto considered. 

To the solution add XH 4 C1, NH 4 H0, (XH 4 ) 2 C0 3 : boil and filter. 



Precipitate 

Ba Ca. 

Wash, dissolve in HC 2 H 3 2 . 

add K 2 Cr0 4 , and filter. 



Filtrate 

Mg Am Xa K. 

Add Ani,HP0 4 , shake, filter. 



Precipitate 


Filtrate 


Precipitate 


Filtrate 


Ba.* 


Ca. 


Mg. 


XH 4 Xa K. 




Test by 
(XH 4 )C 2 6 4 . 




Evap. to dryness, ignite, 






dissolve residue in 








water. 








Test for K bv PtCl 4 . 








Test for Xa bv flame. 








Test orig. sol. for XH 4 



* It is perhaps scarcely necessary to state that this precipitate is 



DISTILLATION. 125 

Note on Classification. — The compounds of barium, calcium, and 
magnesium, like those of the alkali metals, have many analogies ; 
the carbonate, phosphate, and arseniate of each is insoluble in 
water, which sufficiently distinguishes them from the members of 
the class first studied. They possess, however, well-marked differ- 
ences, so that their separation from each other is easy. The solu- 
bility of their hydrates in water marks their connection with the 
alkali metals ; the slightness of that solubility, diminishing as we 
advance further and further from the alkalies, baryta being most 
and magnesia least soluble in water, points to their connection with 
the next class of metals, the hydrates of which are insoluble in 
water. These considerations must not, however, be over-valued. 
Though the solubility of their hydrates places barium nearest and 
magnesium farthest from the alkali metals, the solubility of their 
sulphates gives them the opposite order, magnesium-sulphate being 
most soluble, calcium-sulphate next, strontium-sulphate third (stron- 
tium is a rarer element, which will be mentioned subsequently), and 
barium-sulphate insoluble in water. These elements are sometimes 
spoken of as the metals of the alkaline earths. 

Note. — In conneafcion with the bivalence of the metals Barium, 
Calcium, and Magnesium, it is interesting to note that just as biva- 
lent acidulous radicals give salts containing two atoms of univalent 
basylous radicals (K 2 S0 4 , NaHSO,, H 2 C6 3 , KNaC 4 H 4 6 ), so biva- 
lent basylous radicals yield salts containing two atoms of univalent 
acidulous radicals, as seen in acetonitrate of barium, BaC 2 H 3 2 N0 3 . 
a salt which is a definite compound, and not a mere mixture of ace- 
tate with nitrate of barium. A very large number of such salts is 
known. 

Distillation. 

The water with which, in analysis, solution of a salt or dilution 
of a liquid is effected should be pure. Well- or river-water is unfit 
for the purpose, because containing alkaline and earthy salts (about 
20 to 60 grains per gallon), derived from the soil through which the 
water percolates, and rain-water is not unfrequently contaminated 
with the dust and debris which fall on the roofs whence it is usually 
collected. Such water is purified by distillation, an operation in 
which the water is by ebullition converted into steam, and the steam 
condensed again to water in a separate vessel, the fixed earthy and 
other salts remaining in the vessel in which the water is boiled. 

of course not barium (Ba) itself, but chromate of barium (BaCrOJ, as 
any reader who has carefully gone through the "foregoing analytical 
reactions" will know. The occurrence of chromate of barium at this 
particular place, however, and under the circumstances described, is 
abundant evidence of the presence of barium (Ha, in some form or 
other) in the liquid analyzed— which was a part of the problem to be 
solved by the operator. Similar remarks apply, of course, to the Ca, 
which is finally precipitated as oxalate (CaC 8 4 ), to Mg, which is 
thrown out as ammonio-phosphate (MgNH 4 P0 4 ), to MI,N;i, and K. 
and to the elements similarly alluded to in tin- other subsequent tables 
for " short " directions for analysis. 



126 THE METALLIC RADICALS. 

On the large scale, ebullition is effected in metal boilers having a 
hood or head in which is a lateral opening through which passes 
the steam ; on the small scale, either a common glass flask is em- 
ployed, into the neck of which, by a cork, is inserted a glass tube 

Fig. 28, 




bent to an acute angle, or a retort is used (a, Fig. 28) a sort of long- 
necked Florence flask, dextrously bent near the body by the glass- 
worker to an appropriate angle (hence the name retort, from retor- 
queo, to bend back). Condensation is effected by surrounding the 
lateral steam-tube with cold water. In large stills the steam-tube, 
or condensing-worm, is usually a metal (tin) pipe, twisted into a 
spiral form for the sake of compactness, and so fixed in a tub that a 
few inches of one end of the pipe may pass through and closely fit 
a hole bored near the bottom of the tub. Cold water is kept in con- 
tact with the exterior of the pipe, provision being made for a con- 
tinuous supply to the bottom, while the lighter water heated by the 
condensing steam runs off from the top of the column. The con- 
denser for a flask or retort may be a simple glass tube of any size, 
placed within a second much wider tube (a common long, narrow 
lamp-glass answers very well for experimental operations), the inner 
tube being connected at the extremities of the wider by bored corks ; 
a stream of water passes into one end of the inclosed space (the end 
furthest from the retort) through a small glass tube inserted in the 
cork, and out at the other through a similar tube. The common 
(Liebig's) form of laboratory condenser is a glass tube three-fourths 
of an inch wide and a yard long (6, Fig. 28), surrounded by a 
shorter tin or zinc tube (c, Fig. 28) two inches in diameter, and 
having at each extremity a neck, through which the glass tube 
passes. The ends of the necks of the tin tube, and small portions 
of glass tube near them, are connected by means of a strip of sheet 
caoutchouc carefully bound round, or by short, wide India-rubber 
tubes (d and e, Fig. 28). An aperture near the lower part of the 
tin tube provides for the admission of a current of cold water, and 
a similar aperture near the top (g. Fig. 28) allows the escape of 
heated water. The inner tube may thus constantly be surrounded 
by cold water, and heated vapors passing through it be perfectly 
cooled and condensed in any receiver (h, Fig. 28). 



RECAPITULATION. 127 

The official Water (Aqua, U. S. P.) is to contain " not more than 
1 part of fixed impurities in 10,000 parts/' and to be so free from 
organic matter that when tinted rose-red with permanganate of 
potassium the color should not be destroyed after boiling the fluid 
for 5 minutes, or, in the case of Distilled Water, after setting the 
vessel aside, well covered, for ten hours. 

In distilling several gallons of water for analytical or medicinal 
purposes (Aqua Destillata, U. S. P.) the first two or three pints 
should be rejected, because likely to contain ammoniacal and other 
volatile impurities. 

Rectification is the process of redistilling a distilled liquid. Rec- 
tified spirit is spirit of wine thus treated. 

Dry or destructive distillation is distillation in which the con- 
densed products are directly formed by the decomposing influence 
of the heat applied to the dry or non-volatile substances in the 
retort or still. 



EXERCISE. 



184. Write from memory two or three paragraphs descriptive of 
distillation. 



Recapitulation. 



The subject just alluded to (distillation) naturally excites 
wonder respecting the cause of the physical difference between 
solid, liquid, and gaseous water. (Common observation will 
have suggested to the student that the force of heat has much 
to do with the difference, and if he will turn to the chapter 
on latent heat in any book on Physics he will find that, as 
already indicated (p. 85), when ice liquefies by heat a very 
large amount of heat must be used before the slightest rise of 
temperature occurs. Afterwards the addition of heat makes 
the water hotter and hotter until one other point is reached 
(the boiling-point), when here again a great amount of heat is 
absorbed without causing the slightest rise in temperature. 
Afterwards more heat makes the gaseous water hotter ami 
hotter, until, like a bar of iron, the steam, under special con- 
ditions, is made red hot or white hot.) Different bodies absorb 
different amounts of heat in changing their physical condition 
from solid to liquid or liquid to gas (or vapor). The amount 
is constant for any one body, hence definite comparative num- 
bers may be used for expressing the latent heats of substances. 

The absorption of heat at particular (liquefying ami vapor- 
izing) points must not be confounded with an analogous phys- 
ical action, namely, the absorption of heat which goes on 
when a body is rising in temperature. The amount oi' this 



128 



THE METALLIC RADICALS. 



absorption differs with different substances. That is to say, 
if equal weights of several substances, all at the same tem- 
perature, be all heated to a stated higher temperature, very 
different amounts of fuel will be required. The particular or 
specific amount in each case is always the same, hence the 
specific heats of substances may be expressed by numbers. See 
the chapter on " Specific Heat " in any manual of Physics. 

But after reading what has been stated respecting the con- 
stitution of matter (pp. 42 to 45), the chemical student will, 
in connection with the subject of distillation, be led, once more, 
to think over the subject of the molecular constitution of solid, 
liquid, and gaseous water, and of the molecular condition of 
bodies generally. As previously stated, little can be told him 
respecting the molecular condition of solids and liquids, for 
temperature and pressure affect them unequally, whence we 
conclude that, though the relation to each other of the mole- 
cules of any one substance is constant, this relation is different 
in different bodies. Different gases, however, are not differ- 
ently affected, but similarly affected by temperature and pres- 
sure, whence we conclude that their molecular constitution — ■ 
the relations of their molecules to one another — is similar. 

Another gas, ammonia, has been brought before the reader 
since the molecular constitution of gases was considered. 

A small quantity of ammonia gas inclosed in the upper part 
of a roughly graduated test-tube over mercury (water would 
dissolve it) and exposed to the continuous action of the electric 
spark by means of wires of platinum fused in the sides of the 
tube, is decomposed into its elements nitrogen and hydrogen, 
the bulk of gas operated on being exactly doubled. This 
expansion is not due to the gaseous molecules receding from 
each other, but to every two molecules becoming four similar- 
sized molecules : — 



N 
II 




N 
H 




N 




H 




H 




H 


II 
H 




H 
II 




N 




H 




II 




II 



Here each space (rectangular, chiefly for convenience in 
printing) represents a molecule, and each letter one atom. 
Each space, if regarded as the side of a double cube, may also, 
for the moment, represent two volumes — such two volumes 
yielding, in the decomposition, one volume of nitrogen and 
three volumes of hydrogen, or the four such volumes of ammo- 



zinc. 129 

nia shown in the diagram yielding two volumes of nitrogen 
and six volumes of hydrogen. 

Remembering that a symbol (of a gas) represents one vol* 
ume, that a formula (of a gas) always represents two volumes, 
the pupil will now see how full of meaning is such an equation 
as the following, including, as it does, names of the elements, 
number of the atoms, nature of the molecules, number of the 
molecules, weights of atoms of the molecules, and therefore 
weights of bulks of the bodies, and extent of expansion in the 
disunion of the elements, and therefore their extent of con- 
traction in the act of union : — 

2NH 3 - N 2 + 3H 2 . 



At this stage the learner is again recommended to 
read the paragraphs on the general principles op 
Chemical Philosophy, and to return to them from time 
TO time until they are thoroughly comprehended. 



ZINC, ALUMINIUM, IEON. 

These three elements are classed together for analytical conve- 
nience rather than for more general analogies. 

ZINC. 

Symbol Zn. Atomic weight 64.9. 

Source. — Zinc is tolerably abundant in nature as sulphide (ZnS) 
or blende, and carbonate (ZnC0 3 ), or calamine (from calamus, a 
reed, in allusion to the appearance of the mineral). The ores are 
roasted to expel sulphur, carbonic acid gas, and some impurities, 
and the resulting oxide distilled with charcoal, when the metal 
vaporizes and readily condenses. Zinc is a brittle metal, but at a 
temperature somewhat below 300° F. is malleable, and may be rolled 
into thin sheets. Above 400° it is again brittle, and may then be 
pulverized. At 773° F. it melts, and at a bright red heat is volatile. 
Zinc in exceptionally fine powder ignites spontaneously, especially 
if damp or if stored in a warm place. 

Uses. — Its use as a metal is familiar ; alloyed with nickel and cop- 
per it yields german silver, with twice its weight of copper forms 
common brass, and as a coating on iron (the so-called galvanized 
iron) greatly retards the formation of rust. Most of the salts of zinc 
are prepared directly or indirectly from the \ncti\\ (Zincum, V. S. P.). 

Quant ivalence. — The atom of zinc is bivalent, /a/'. 

Molecular Weight — Some remarks on this point will he made 
under Mercury. 



130 THE METALLIC RADICALS. 

Reactions having (a) Synthetical and (b) Analytical 
Interest. 

(a) Synthetical Reactions. 
Sulphate of Zinc. 
First Synthetical Reaction. — Heat zinc (4 parts) with water 
(20 parts) and sulphuric acid (3 fl. parts) in a test-tube (or 
larger vessel) until gas ceases to be evolved ; solution of sul- 
phate of zinc (ZnS0 4 ) results. Filter (to separate the particles 
of lead, carbon, etc., commonly contained in sheet zinc), and 
concentrate the solution in an evaporating-dish ; on cooling, 
colorless, transparent, prismatic crystals of Sulphate of Zinc 
(ZnSO*,7H 2 0) are deposited {Zinci Sulphas, U. S. P.). 
Zn 2 + 2H 2 S0 4 + *H 2 = 2ZnS0 4 + 2H 2 -f ccH 2 

Zinc. Sulphuric acid. Water. Sulphate of zinc. Hydrogen. Water. 

Zinc does not displace hydrogen from the sulphuric acid alone, 
nor from the water alone, yet it does from the mixture. The pos- 
sible explanation is that as sulphuric acid combines with several 
different quantities of water to form definite hydrous compounds 
(HjjSO^HjO ; H 2 S0 4 ,2H 2 ; etc.), it is one or more of these that 
is decomposed with elimination of hydrogen. At present we can 
only say that an unknown (x) amount of water is required in the 
reaction. 

Note. — This reaction affords hydrogen and sulphate of zinc ; it 
also develops electricity. Of several methods of evolving hydro- 
gen, it is the most convenient ; of the two or three means of pre- 
paring sulphate of zinc, it is the most commonly employed ; and 
of the many reactions which may be utilized in the development of 
dynamic electricity, it is one of the most convenient. The appa- 
ratus in which the reaction is effected differs according to the re- 
quirements of the operator : if the sulphate of zinc alone is wanted, 
an open dish is all that is necessary, the action being, perhaps, 
accelerated by heat ; if hydrogen, a closed vessel and delivery-tube 5 
if electricity, square vessels called cells, and certain complementary 
materials, forming altogether what is termed a battery. In each 
operation for one product, the other two are commonly wasted. It 
would not be difficult for the operator, as a matter of amusement, to 
construct an apparatus from which all three products should be col- 
lected. 

Purification. — Impure sulphate of zinc may be purified in the 
same manner as impure chloride (see next reaction). 

Sulphate of zinc is isomorphous with sulphate of magnesium, and 
like that salt, loses six-sevenths of its water of crystallization at 
212° F. 

Chloride of Zinc. 

Second Synthetical Reaction. — Dissolve zinc in hydrochloric 
acid mixed with half its bulk of water ; the resulting solution 



ZINC. 131 

contains chloride of zinc. Evaporate the liquid till no more 
steam escapes ; Chloride of Zinc (ZnCl 2 ) in a state of fusion 
remains, and on cooling is obtained as an opaque white solid 
(Zinci G hloridum, U. S. P.). 

It is soluble in water, alcohol, or ether. 

Zn 2 + 4HC1 = 2ZnCl 2 + 2H 2 

Zinc. Hydrochloric acid. Chloride of zinc. Hydrogen. 

This reaction is analogous to that previously prescribed. The 
Burnett deodorizing or disinfecting liquid is solution of chloride of 
zinc. 

Purification of Chloride or Sulphate of Zinc. — Zinc sometimes 
contains traces of iron or lead 5 and these, like zinc, are dissolved 
by most acids, with formation of soluble salts ; they may be recog- 
nized in the liquids by applying the tests described hereafter to a 
little of the solution in a test-tube. Should either be present in the 
above solution, a little chlorine-water is added to the liquid till the 
odor of chlorine is permanent, and then the whole well shaken with 
some hydrate of zinc or the common official "carbonate" of zinc 
(really hydrato-carbonate — see p. 132). In this way iron is precipi- 
tated as ferric hydrate, and lead as peroxide : — 

*2FeCl 2 + Cl ? = *Fe 2 Cl 6 

Ferrous chloride. Chlorine. Ferric chloride. 

Fe 2 Cl 6 + 3ZnC0 3 + 311,0 = Fe 2 6HO + 3ZnCl 2 + 3C0 2 

Ferric Carbonate Water. Ferric hydrate. Chloride Carbonic 

chloride. of zinc. of zinc. acid gas. 

PbCl 2 + Cl 2 + 2ZnC0 3 = Pb0 2 + 2ZnCl 2 + 2C0 2 

Chloride Chlorine. Carbonate Peroxide Chloride Carbonic 

of lead. of zinc. of lead. of zinc. acid gas. 

In the British Pharmacopoeia the possible presence of impurities in 
the zinc is recognized, and the process of purification just described 
incorporated with the process of preparation of Zinci Ckloridum, 
Liquor Zinci Chloridi, and Zinci Sulphas. In the purification of 
the sulphate of zinc the action of chlorine on any ferrous sulphate 
will result in the formation of ferric sulphate as well as ferric 
chloride : — 

6FeS0 4 + Cl 6 == 2(Fe 2 3SO,) + Fe 2 Cl 6 ; 

carbonate of zinc will then give chloride as well as sulphate of zinc, 
and thus the whole quantity of sulphate of zinc be slightly contami- 
nated by chloride. On evaporating and crystallizing, however, the 
chloride of zinc will be retained in the mother-liquor. This process 
admits of general application. 

For Liquor Zinci Chloridi, B. P., 1 pound of zinc is placed in a 
mixture of 44 fluidounces of hydrochloric acid and 20 of water, the 

* It will be noticed that the atom of iron is represented, in these 
equations, as exerting both bivalent and trivalent activity ; this will be 
alluded to when iron comes under consideration. 



132 THE METALLIC RADICALS. 

mixture ultimately warmed until no more gas escapes, filtered into a 
bottle, chlorine-water added until the liquid after shaking smells 
fairly of chlorine, about half an ounce or somewhat more of carbonate 
of zinc shaken up with the solution until a brown precipitate (of fer- 
ric hydrate or peroxide of lead, or both) appears, the whole filtered, 
and the filtrate evaporated to 40 fluidounces. One fluidounce con- 
tains 366 grains of chloride of zinc. If on testing a little of the 
solution first produced with ammonia and sulphydrate of ammo- 
nium, no black precipitate is produced, neither iron nor lead was 
present in the zinc, and the treatment with chlorine-waterand car- 
bonate of zinc is to be omitted. The Liquor Zinci Chloridi, U. S. P., 
is prepared by a somewhat similar process ; nitric acid, however, is 
used instead of chlorine-water ; the solution contains " about 50 per 
cent, of the salt (ZnCl 2 )," sp. gr. 1.555. It is miscible with alcohol 
in all proportions, indicating absence of basic chloride of zinc. 

Bromide of Zinc, ZnBe 2 (Zinci Bromidum, U. S. P.) may be made 
by the action of zinc on hydrobromic acid and evaporation to dry- 
ness. It is a white powder, but may be sublimed in needles. 

Iodide of Zinc, Znl 2 (Zinci Iodidum, U. S. P.) may be made from 
its elements. It is a white powder, but when volatilized condenses 
in acicular prisms. 

Carbonate of Zinc. 

Third Synthetical Reaction. — To solution of any given 
quantity of sulphate of zinc in twice its weight of water (in 
a test-tube, evaporating-basin, or other large or small vessel), 
add about an equal quantity of carbonate of sodium, also dis- 
solved in twice its weight of water, and boil ; the resulting 
white precipitate is so-called Carbonate of Zinc (Zinci Car- 
bonas, B. P., Zinci Carbonas Prsecipitatuz, U. S. P.), a mix- 
ture of carbonate (ZnC0 3 ) and hydrate (Zn2HO), in the pro- 
portion of two molecules of the former and three of the latter. 
It may be washed, drained, and dried in the usual manner. It 
is used in the arts under the name of zinc-white. 

5ZnSO, + 3H 2 + 5Xa 2 C0 3 = 

Sulphate of zinc. Water. Carbonate of sodium. 

2ZnC0 3 ,3ZnH 2 2 + 3C0 2 + 5Na 2 S0 4 

Official carbonate of zinc. Carbonic acid gas. Sulphate of sodium. 

Cidamina Prctparata, B. P., Prepared Calamine, is ferruginous 
carbonate of zinc, or calamine, calcined, powdered, and freed from 
gritty particles by elutriation. 

Elutriation (Lat. elutriatus, elutrio, eluo, to wash out) is the act of 
straining off water containing lighter particles in suspension from 
heavier and coarser particles which have become deposited. The 
decanted fluid yields a sediment of fine particles on standing. 

Acetate of Zinc. 

Fourth Synthetical Reaction. — Collect in a filter the precipitate 



zinc. 133 

obtained in the last reaction, wash with distilled water, and dis- 
solve a portion in strong acetic acid ; the resulting solution con- 
tains acetate of zinc (Zn2C 2 H 3 2 ), and, on evaporating and set- 
ting aside, yields lamellar pearly crystals (Zn2C 2 H 3 2 ,3H 2 0) 
(Zinci Acetas, U. S. P.). 

2ZnC0 3 ,3ZnH 2 2 + 10HC 2 H 3 O 2 = 

Official carbonate of zinc. Acetic acid. 

5(Zn2C 2 H 3 2 ) + 8H 2 _j_ 2C0 2 

Acetate of zinc. Water. Carbonic acid gas. 

Another process consists in digesting oxide of zinc in acetic 
acid, heating the mixture to boiling-point, filtering while hot, 
and setting aside the clear solution to crystallize. 

Oxide of Zinc. 

Fifth Synthetical Reaction. — Dry the remainder of the pre- 
cipitated carbonate (by placing the open filter on a plate over 
a dish of water kept boiling), and then heat it in a small cru- 
cible till it ceases to effervesce on the addition of water and 
acid to trial samples taken out of the crucible from time to 
time ; the product is Oxide of Zinc (Zinci Oxidum, U. S. P.). 

2ZnC0 3 ,3ZnH 2 2 = 5ZnO + 3H 2 + 2C0 2 

Official carbonate Oxide of Water. Carbonic 

of zinc. zinc. acid gas. 

Note. — This oxide is yellow while hot, and of a very pale yellow 
or slight buff tint when cold, not actually white, like the oxides pre- 
pared by the combustion of zinc in air. The preparation of the lat- 
ter variety, which also occurs in commerce, can only be practically 
accomplished on the large scale, but the chief features of the action 
may be observed by heating a piece of zinc on charcoal in the blow- 
pipe-flame (Fig. 29) till it burns ; flocks escape, float about in the 
air, and slowly fall. These are the old Flores Zinci, Lana Philoso- 
phica, or Nihilum Album. 

Fig. 29. Fig. 30. 




Tho Blowpipe. 



134 THE METALLIC RADICALS. 

A clear blowpipe-flame consists more or less of two portions 
(see Fig. 30), an inner cone, at the apex of which are hot gases 
greedy of oxygen, and an outer cone, at the apex of which is 
excess of hot oxygen. At the latter point oxidizable metals, 
etc. are readily oxidized, as in the foregoing experiment, and 
that part of the flame is therefore termed the oxidizing flame ; 
in the inner flame oxides and other compounds (a grain of 
acetate of lead may be employed for illustration) are reduced 
to the metallic state, hence that part is termed the reducing 
flame. A blowpipe-flame is much altered in character by 
slight variations in the position of the nozzle of the blowpipe, 
by the form of the nozzle, by the force with which air is ex- 
pelled from the blowpipe, and by the character of the jet of 
gas. Oxide of zinc slowly absorbs carbonic acid from moist 
air, and is partly reconverted into hydrato-carborrate. 

Valerianate of Zinc. 

Sixth Synthetical Reaction. — Valerianate of Zinc (Zn2C 5 - 
H 9 2 ,H 2 0) (Zinci Valeriaiias, U. S. P.) is prepared by mixing 
strong solutions of sulphate of zinc and valerianate of sodium, 
cooling, separating the white pearly crystalline matter, evapor- 
ating at 200° F. to a low bulk, cooling, again separating the 
lamellar crystals, washing the whole product with a small 
quantity of cold distilled water, draining, and drying by ex- 
posure to air at ordinary temperatures. Valerianate of zinc is 
soluble in ether, alcohol, or hot water. 

ZnS0 4 + 2NaC 5 H 9 2 = Na 2 S0 4 + Zn2C 5 H 9 2 

Sulphate Valerianate of Sulphate of Valerianate 

of zinc. sodium. sodium. of zinc. 

Note. — The compounds of zinc described in the foregoing six reac- 
tions are the only ones mentioned in the British Pharmacopoeia ; the 
processes are also those of that work. Sulphide and Hydrate of Zinc 
are mentioned in the following analytical paragraphs. The formula 
of Sulphite of Zinc is ZnS0 3 ,3"H 2 0. 

(b) Reactions having Analytical Interest (Tests'). 

First Analytical Reaction. — To solution of a zinc salt (sul- 
phate, e. g.) in a test-tube, add solution of sulphydrate of am- 
monium (NH 4 HS) ; white sulphide of zinc (ZnS) is precipitated, 
insoluble in acetic, soluble in the stronger acids. 

Note. — This is the only white sulphide that will be met with. Its 
formation, on the addition of the sulphydrate of ammonium, is 
therefore highly characteristic of zinc. If the zinc salt contains 
iron or lead as impurities, the precipitate will have a dark ap- 
pearance, the sulphides of those metals being black. Hydrate of 
aluminium, which is also white and precipitated by sulphydrate 



zinc. 135 

of ammonium, is the only substance sulphide of zinc is likely to 
be mistaken for, and vice versa; but, as will be seen immediately, 
there are good means of distinguishing these from each other. 

Second Analytical Reaction. — To solution of a zinc salt add 
ammonia ; white hydrate of zinc (Zn2HO) is precipitated. 
Add excess of ammonia ; the precipitate is redissolved. 

This reaction at once distinguishes a zinc salt from an aluminium 
salt, hydrate of aluminium being insoluble in dilute ammonia. 

Other Analytical Reactions. — The fixed alkali-hydrates afford 
a similar reaction to that just mentioned, the hydrate of zinc 

redissolving if the alkali is free from carbonate. Carbonate 

of ammonium yields a white precipitate of carbonate and hy- 
drate, soluble in excess. The fixed alkaline carbonates give 

a similar precipitate, which is not redissolved if the mixed 

solution and precipitate be well boiled. Ferrocyanide of 

potassium precipitates white ferrocyanide of zinc (Zn 2 FeCy 6 ). 

Sulphate of magnesium, which is isomorphous with, and in- 
distinguishable in appearance from, sulphate of zinc, is not pre- 
cipitated from its solutions either by ferrocyanide of potassium 
or sulphydrate of ammonium. 

Antidotes. — There are no efficient chemical means of counteract- 
ing the poisonous effects of zinc. Large doses, fortunately, act as 
powerful emetics. If vomiting has not occurred, or apparently to 
an insufficient extent, solution of carbonate of sodium (common 
washing salt), immediately followed by white of egg and demulcents, 
may be administered. 






QUESTIONS AND EXERCISES. 

185. Give the sources and uses of metallic zinc. 

186. Explain by a diagram what occurs when zinc is dissolved in 
diluted sulphuric acid. 

187. How may solutions of Chloride and of Sulphate of Zinc be 
purified from the salts of iron ? Give equations for the reactions. 

188. State the formula of Carbonate of Zinc, and illustrate by a 
diagram the reaction which takes place in its production. 

189. Give an equation for the synthesis of Acetate of Zinc. 

190. In what respect does Oxide of Zinc, resulting from the igni- 
tion of the carbonate, differ from that produced during the combus- 
tion of the metal ? 

191. How is Valerianate of Zinc prepared? 

1 92. What are the properties of Valerianate of Zinc ? 

193. Name the more important tests of Zinc. 

194. Tlow would you distinguish, chemically, between solutions 
of Sulphate of Zinc and Alum? 

195. Describe the treatment in cases of poisoning by zinc salts. 

196. Give reactions distinguishing Sulphate of Zinc from Sulphate 
of Magnesium. 



136 THE METALLIC RADICALS. 

ALUMINIUM. 

Symbol Al. Atomic weight 27. 

Note. — In the formulae of aluminium salts it will be observed 
that to one atom of metal there are three atoms of other univalent 
radicals ; hence, apparently, the atom of aluminium is trivalent, 
AY". But possibly it is quadrivalent; for one molecule of alu- 
minium compounds includes two atoms of the metal, three-fourths 
only of whose power may be supposed to be exerted in retaining the 
other constituents of the molecule, the remaining fourth enabling the 
aluminium atoms themselves to keep together. This is graphically 
shown in the following formula of chloride of aluminium (A1 2 C1 6 ), 
which represents each aluminium atom as a body having four arms 

CI CI 

I I 

CI Al Al— CI 

I I 

Jl Jl 

or bonds, three of which are engaged in grasping the arms of univ- 
alent chlorine atoms, while the fourth grasps the corresponding arm 
of its brother aluminium atom. Such graphic formulae, as they are 
called, are useful in facilitating the acquirement of hypotheses re- 
garding the constitution of chemical substances, especially if the 
error be avoided of supposing that they are pictures either of the 
position or absolute power of atoms in a molecule, or indeed, the 
true representation of a molecule at all ; for on this point man 
knows little or nothing. A1C1 3 may be the formula at very high 
temperatures. 

Source. — Aluminium is very abundant in nature, chiefly as silicate, 
in clays, slate, marl, granite, basalt, and a large number of minerals. 
Mica consists chiefly of silicates of aluminium, iron, and potassium. 
Ix'oiien-stone is a soft and friable aluminium silicate containing a little 
organic matter. The sapphire and ruby are almost pure oxide of 
aluminium. The metal aluminium is obtained from the double 
chloride of aluminium and sodium, by the action of metallic sodium, 
the source of the chloride being the mineral bauxite — a more or less 
ferruginous hydrate of aluminium. 

Aluminium readily alloys with other metals. One part fused 
with nine of copper gives aluminium-bronze. 

Alum (Alumen, U. S. P.), a double sulphate of aluminium and 
potassium (A1 2 3S0 4 ,K 2 S0 4 ,24H 2 0), may be obtained from aluminous 
schist (from cxtorbc, schistos, divided), a sort of pyritous slate or shale, 
by exposure to air ; oxidation and chemical change produce sulphate 
of aluminium, sulphate of iron, and silica, from the silicate of 
aluminium and bisulphide of iron (iron pyrites) originally present 
in the shale. The sulphate of aluminium and sulphate of iron are 
dissolved out of the mass by water, and sulphate of potassium 



ALUMINIUM. 137 

added ; on concentrating the liquid, alum crystallizes out, while the 
more soluble iron salt remains in the mother liquor. 

It is more frequently prepared by directly decomposing the sili- 
cate of aluminium in the calcined shale of the coal-measures by hot 
sulphuric acid, sulphate of potassium being added from time to 
time until a solution strong enough to crystallize is obtained. The 
liquid well agitated during cooling deposits alum, in minute crys- 
tals, termed alum-flour, which is afterwards recrystallized. 

Alums. — There are several alums, iron or chromium taking the 
place of aluminium, and ammonium or sodium that of potassium, all 
crystallizing in an eight-sided form, the octahedron — a sort of double 
pyramid. These are apparently alike in chemical constitution, and 
their general formula (M = either metal) is M" / 2 3S0 4 ,M / 2 S0 4 ,24H 2 0. 
The alum of the manufacturer commonly occurs in colorless, trans- 
parent, octahedral crystals, massed in lumps, which are roughly 
broken up for trade purposes, but still exhibit the faces of octahedra. 
It is liable to contain sulphate of ammonium or sulphate of potas- 
sium, according as one or other is the cheaper. 

Sulphate of Aluminium (A1 2 3S0 4 ,9H 2 0), or Alum Cake, prepared 
from natural silicates in the manner just described, is a common 
article of trade, serving most of the manufacturing purposes for 
which alum was formerly employed. It is official in the United 
States Pharmacopoeia {Aluminii Sulphas). It may be made by dis- 
solving hydrate of aluminium in diluted sulphuric acid, with subse- 
quent removal of water by evaporation. 

AL6HO + 3H 2 S0 4 = AL3SO, + 6H 2 0. 

The Jiydrate of aluminium {Aluminii Hydras, U. S. P.) is to be 
prepared by the addition of solution of alum to solution of carbo- 
nate of sodium, the precipitated hydrate being collected on a filter 
and well washed. 

AL3S0 4 ,K 2 S0 4 + 3Na 2 C0 3 + 3H 2 = Al 2 6HO + K 2 S0 4 + 3Na 2 S0 4 
+ 3C0 2 . 

Preparation of Alum. — Prepare alum by heating a small quan- 
tity of powdered pipe-clay (silicate of aluminium) with about twice 
its weight of sulphuric acid for some time, dissolving out the result- 
ing sulphate of aluminium and excess of sulphuric acid by water, 
and adding carbonate of potassium to the clear filtered solution only 
until, after well stirring, the excess of acid is neutralized. (If too 
much carbonate be added, the hydrate of aluminium precipitated 
when the carbonate is first poured in will not be redissolved on well 
mixing the whole. Perhaps the readiest indication of neutrality in 
this and similar cases is the presence of a little precipitate after 
stirring and warming the mixture.) On evaporating the clear solu- 
tion crystals of alum are obtained. 

The Ammonio-ferric Alum or Ammonio-ferric Sulphateoi Amer- 
ican pharmacy (Ferri et Ammonii Sulphas, V. S. P.) may be made 
by adding sulphate of ammonium to a hot solution of persulphate 
of iron, and setting the liquid aside to crystallize. It forms pale 






138 THE METALLIC RADICALS. 

violet octahedral crystals expressed by the formula Fe 2 3S0 4 j 
(NHJ 2 S0 4 ,24H 2 0. 

Dried Alum (Alumen Exsiccatum, U. S. P.) is alum from which 
the water of crystallization has been expelled by heat, the tempera- 
ture not exceeding 205° C. or 400° F. By calculation from the 
molecular weight of alum, it will be found that the salt contains 
between 45 and 46 per cent, of water. At temperatures above 4( M >° 
ammonium alum is decomposed, sulphate of ammonium and sul- 
phuric anhydride escaping, and pure oxide of aluminium (A1 2 3 ) 
remaining. Dried alum rapidly reabsorbs water from the atmo- 
sphere. 

Roche alum, or Rock alum (roche, French, rock), is the name of 
an impure native variety of alum containing iron. The article sold 
under this name is sometimes an artificial mixture of common alum 
with oxide of iron. 

Eeactions having Analytical Interest. 

First Analytical Reaction. — To a solution of an aluminium 
salt (alam, for example, which contains sulphate of aluminium) 
add sulphydrate of ammonium (NH + HS) ; a gelatinous white 
precipitate of hydrate of aluminium falls : — 

A1 2 3S0 4 + 6AmHS + 6H 2 = Al 2 6HO + 3Am 2 S0 4 + 6H 2 S. 

Second Analytical Reaction. — To a solution of alum add 
ammonia, NH 4 HO ; hydrate of aluminium falls : add excess of 
ammonia ; the precipitate is, practically, insoluble. 

Principle of Dyeing by help of Mordants. — The precipitated 
hydrate of aluminium, or alumina, has great affinity for vege- 
table coloring-matters and also for the fibre of cloth. Once 
more perform the above experiment, but before adding the 
ammonia introduce some decoction of logwood, solution of 
cochineal, or other similar colored liquid, into the test-tube. 
Add now the ammonia, and set the tube aside for the alumina 
to fall ; the latter takes down with it all the coloring principle. 
In dye-works the fabrics are passed through liquids holding 
the alumina but weakly in solution, and then through the color- 
ing solutions ; from the first bath the fibres abstract alumina, 
and from the second the alumina abstracts coloring-matter. 
Some other metallic hydrates, notably those of tin and iron, 
resemble alumina in this property ; they are all termed mor- 
dants (from mordens, biting) ; the substances they form with 
coloring-matters have the name of lakes. 

Third Analytical Reaction. — To the alum add solution of 
potash ; again hydrate of aluminium falls. Add excess of 
potash, and agitate ; the precipitate dissolves. 

Hydrate of aluminium may be precipitated from this solu- 



IRON. 139 

tion by neutralizing the potash with hydrochloric acid, and 
adding ammonia until, after shaking, the mixture has an am- 
moniacal smell, or by adding solution of chloride of ammonium 
to the potash liquid. But the former way is the better ; for it 
is difficult to know when a sufficiency of the chloride of am- 
monium has been poured in, whereas reaction with blue and 
red litmus-paper at once enables the operator to know when 
excess of hydrochloric acid or ammonia has been added. 

Alkaline phosphates, arseniates, and salts of other acidulous 
radicals also decompose solutions of aluminium salts and produce 
insoluble compounds of that metal, with the several acidulous 
radicals, but the resulting precipitates are of no special interest. 



QUESTIONS AND EXERCISES. 

197. What is there remarkable about the quantivalence of alu- 
minium ? 

198. Practically, what is the quantivalence of the atom of alu- 
minium ? 

199. Enumerate the chief natural compounds of aluminium. 

200. Write down a formula which will represent either of the 
Alums. 

201. Which alum is official, and commonly employed in the 
arts? 

202. State the source and explain the formation of alum. 

203. What is the crystalline form of alum ? Work a sum showing 
how much Dried Alum is theoretically producible from 100 pounds 
of alum. Ans. 52 lbs. 6 oz. 

204. Show by figures how ordinary ammonium alum is capable of 
yielding 11.356 per cent, of alumina. 

205. Why are aluminium compounds used in. dyeing? 

206. How are salts of aluminium analytically distinguished from 
those of zinc? 



IRON. 

Symbol Fe. Atomic weight 55.9. 

Sources. — Compounds of iron are abundant in nature. Magnetic 
Iron Ore, or Loadstone (Lodestonc or Leadstone. from the Saxon 
Icedan, to lead, in allusion to its use, or rather to the use of magnets 
made from it, in navigation), is the chief ore from which Swedish 
iron is made ; it is a mixture of ferrous and ferric oxides (l<YO,Fe.,O..Y 
Much of the Russian iron is made from Specular Iron Ore (from 
speculum, a mirror, in allusion to the lustrous nature oi^ the crystals 
of this mineral). This and Red Ilannatite (from a)ua, hainuu Mood, 
so named from the color of its streak), an ore raised in Lancashire. 
are composed of ferric oxide only (Fe.,0..). Brown ll<v»ntlit<\ an 



140 THE METALLIC RADICALS. 

oxyhydrate, is the source of much of the French iron. Spathic Iron 
Ore (from spatha, a slice, in allusion to the lamellar structure of the 
ore) is a ferrous carbonate (FeC0 3 ). An impure ferrous carbonate 
forms the Clay Ironstone, whence most of the English iron is derived. 
The chief Scotch ore is also an impure carbonate, containing much 
bituminous matter : it is known as Black Band. Iron Pyrites (from 
7ri>p, pur. fire, in allusion to the production of sparks when sharply 
struck) (FeS 2 ) is a yellow lustrous mineral, of use only for its 
sulphur. As met with in coal it is commonly termed coal brasses. 
Ferrous carbonate (FeC0 3 ), chloride (FeCl 2 ,4H 2 0), and sulphate 
(FeS0 4 ,7H 2 0) sometimes occur in springs, the water of which is 
hence termed chalybeate (chalybs, steel). 

Process. — Iron is obtained from its ores by processes of roasting, 
and reduction of the resulting impure oxide with coal or charcoal in 
the presence of chalk, the latter uniting with the sand, clay, etc. to 
form a fusible slag. The cast iron thus produced may be converted 
into wrought iron by burning out the 4 or 5 per cent, of carbon, 
silicon, and other impurities present, by oxidation in a furnace, an 
operation which is termed puddling. Steel is iron containing from 
one to two per cent, of carbon, and is made by the now celebrated 
Bessemer process of burning out from cast iron the variable amount 
of carbon it contains, and then adding melted iron containing a 
known proportion of carbon. The official varieties of the metal are 
"metallic iron, in the form of line, bright, and non-elastic wire" 
(Ferrum, U. S. P.) ; and " annealed iron wire," having a diameter about 
0.005 of an inch (about Xo. 35 wire gauge), or wrought-iron nails, 
free from oxide (Ferrum, B. P.), the conditions in which it is most 
easily employed for conversion into its compounds. In the form of 
a fine powder (see 17 Reae.) metallic iron is employed as a medicine. 

Properties. — The specific gravity of pure iron is 7.844, of the best 
bar iron 7.7 ; its color is bluish-white or gray. Bar iron requires the 
highest heat of a wind-furnace for fusion, but below that temperature 
assumes a pasty consistence, and in that state two pieces may be 
joined or welded (Germ, wellen. to join) by the pressure of blows 
from a hammer. A little sand thrown on to the hot metal facilitates 
this operation by forming with the superficial oxide of iron a fusible 
slag, which is dispersed by the blows : the purely metallic surfaces 
are thus better enabled to come into thorough contact and enter into 
perfect union. Iron is highly ductile, and of all common metals pos- 
sesses the greatest amount of tenacity. At a high temperature it 
burns in the air. forming oxide of iron. Rust of iron is chiefly red 
oxide of iron, with a little ferrous oxide and carbonate ; it is pro- 
daced by action of the moist carbonic acid of the air and subsequent 
oxidation. Steam passed over scrap iron heated to redness gives 
hydrogen gas and black oxide of iron. Iron exposed at a high tem- 
perature to oxidation by a limited amount of steam (Barff) or air 
(Bower) becomes coated with magnetic oxide of so closely coherent 
and adherent a nature that the metal is more or less permanently 
protected from alteration by atmospheric and many other influences. 

Quantivalence. — Iron combines with other elements and radicals 
in two proportions ; those salts in which the atom of iron appears tc 



IRON. 141 

possess inferior affinities (in which the other radicals are in the less 
amount) are termed ferrous, the higher being ferric salts. In the 
former the iron exerts bivalent (Fe // ), in the latter trivalent activity 
(Ye /// or Fe 2 VI ), as seen in the formulse of the chlorides, FeCl 2 (pos- 
sibly Fe 2 Cl 4 ) and Fe 2 Cl 6 (perhaps FeCl 3 at very high temperatures). 

The atom of iron is also sometimes considered to be sexivalent, on 
account of the analogy of its compounds with those of chromium, 
which is sexivalent, if the formula of its fluoride (CrF 6 ) be correct, 
and because the composition of ferrate of potassium (K 2 Fe0 4 ), a deep 
purple salt (obtained on warming a mixture, in a test-tube, of a few 
fragments of solid hydrate of potassium and of perchloride of iron 
with a few drops of bromine), is best explained on the assumption 
of the sexivalence of its iron. 

Why the quantivalence of the atom of iron should vary is not at 
present known. 

The Nomenclature of Iron Salts. — For educational and descrip- 
tive purposes the two classes of iron compounds are very conveniently 
spoken of as ferrous and ferric, the syllable "ferr" common to all 
indicating their allied ferruginous character, the syllables ous and ic 
indicating the lower and higher class respectively — functions fulfilled 
by these two syllables in other similar cases (sulphurous and sul- 
phuric, mercurous and mercuric). Officially the iron salts are known 
by other names, thus, Sulphate of Iron (Ferri Sulphas) and Phos- 
phate of Iron {Ferri Phosphas), names which are chemically inex- 
plicit, for there are two sulphates, and two phosphates, and the terms 
do not define which salt is intended. Consistency and uniformity 
would demand that the names Ferrous Sulphate, Ferrous Phosphate, 
or similar terms, should be employed. Practically, however, the old 
names cause no confusion, inasmuch as, commonly, only one sulphate, 
phosphate, etc. are used in medicine ; moreover, the higher salts 
usually have the prefix per attached (as persulphate, perchloride). 
These names are already well known, can be easily rendered in Latin, 
and then admit of simple abbreviations and adaptations such as are 
employed in prescriptions, advantages not possessed by the more 
rational terms. While, therefore, the comprehension of the chem- 
istry of iron is rendered simple and intelligible by the use of the 
terms ferrous and ferric, the employment of older and less definite 
names may very well be continued in pharmacy as being practically 
more convenient. 



Reactions having (a) Synthetical and (l>) Analyticai 
Interest. 

(ci) Synthetical Reactions. 

FERROUS SALTS. 
Green Sulphate of Iron. Ferrous Sulphate. 
First Synthetical Reaction. — Place iron (small tacks) in sul- 
phuric acid diluted with eight times its bulk of water (in a 



142 . THE METALLIC RADICALS. 

test-tube, basin, or other vessel of any required size), accele- 
rating the action by heat until effervescence ceases. 
Fe 2 + 2H 2 S0 4 + *H 2 = 2FeS0 4 + 2H 2 -f xU 2 

Iron. Sulphuric acid. Water. Ferrous sulphate. Hydrogen. Water. 

The solution contains what is generally known as Sulphate 
of Iron, that is, Ferrous Sulphate, the lower of the two sul- 
phates, and will yield crystals of that substance (FeS0 4 ,7H 2 0) 
{Ferri Sulphas, U. S. P.) on cooling or on further evaporation ; 
or if the hot concentrated solutions be poured into alcohol, the 
mixture being well stirred, the sulphate is at once thrown 
down in minute crystals {Ferri Sulphas Frsecipitatus, U. S. P.). 
At a temperature of 300° F. ferrous sulphate loses six-sevenths 
of its water, and becomes the Ferri Sulphas Fxsiccatus, U. S. P., 
a salt used in the preparation of Fihlse Aloes et Ferri, U. S. P. 
(For the nature of the chemical action with iron and diluted 
sulphuric acid see the analogous zinc reaction on p. 130.) 

Other Sources of Ferrous Sulphate. — In the laboratory ferrous 
sulphate is often obtained as a by-product in making sulphuretted 
hydrogen : — 

FeS + II 2 S0 4 = H 2 S + FeS0 4 . 

In manufactories it occurs as a by-product in the decomposition of 
aluminous shale, as already noticed (p. 135). 

Ten grains of granulated sulphate of iron dissolved in one ounce 
of water constitute " Solution of Sulphate of Iron," B. P. " The 
solution should be recently prepared." 

Notes. — Ferrous sulphate is sometimes termed green vitriol. Vit- 
riol (from vitrum, glass) was originally the name of any transparent 
crystalline substance, but afterwards restricted to the sulphates of 
zinc, iron, and copper, which were, and still are, occasionally known 
as white, green, and blue vitriol. Copperas (probably originally 
copper-rust, a term applied to verdigris and other green incrusta- 
tions of copper) is another name for this sulphate of iron, some- 
times distinguished as green copperas, sulphate of copper being blue 
copperas. Solid sulphate of iron is a constituent of Pilulw Aloes et 
Ferri, B. P. Ferrous sulphate forms a light-green double salt with 
sulphate of ammonium. 

Ferrous sulphate, when exposed to the air, gradually turns brown 
through absorption of oxygen, ferric oxy sulphate (Fe 2 02S0 4 ) being 
formed. The latter is not completely dissolved by water, owing to 
the formation of a still lower insoluble oxysalt (Fe 4 5 S0 4 ) and solu- 
ble ferric sulphate, 5(Fc 2 02S0 4 ) = Fe 4 5 S0 4 + 3(Fe 2 3S0 4 ). 

Iron heated with undiluted sulphuric acid gives sulphurous acid 
gas and ferrous sulphate : — 

Fe 2 + 4H 2 S0 4 = 2S0 2 + 2FeS0 4 + 4H 2 0. 
Carbonate of Iron. Ferrous Carbonate. 

Set ond Synthetical Reaction. — To solution of ferrous sul- 



IRON. 143 

phate, boiling, in a test-tube, add solution of bicarbonate of 
sodium (NaHC0 3 ) in recently boiled water; a white precipitate 
of ferrous carbonate (FeC0 3 ) is thrown down, rapidly becoming 
light green, bluish green, and, after a long, time, red, through 
absorption of oxygen, evolution of carbonic acid gas, and for- 
mation of ferric oxyhydrate. 

FeS0 4 + 2NaHC0 3 = FeC0 3 + Na 2 S0 4 + H 2 + C0 2 

Ferrous Bicarbonate of Ferrous Sulphate of Water. Carbonic 

sulphate. sodium. carbonate. sodium. acid gas. 

Saccharated Carbonate of Iron. — The above precipitate, rapidly 
washed with hot, well-boiled distilled water, and the moist powder 
mixed with sugar, and quickly dried — in short, all possible precau- 
tions taken to avoid exposure to air — forms the saccharated carbo- 
nate of iron {Ferri Carbonas Saccharatus, U. S. P.). 

The official proportions are 10 of the sulphate dissolved in 40 of 
hot water, and 7 of the bicarbonate dissolved in 100 of warm water, 
and each filtered. The former is then added to the latter in a flask, 
the mixture shaken, the precipitate washed by decantation until the 
washings give only a very slight turbidity with chloride of barium, 
drained, and while still somewhat moist mixed with 16 parts of 
sugar, and finally dried over a water-bath. 

Carbonate of iron, mixed with honey and sugar, forms the Massa 
Ferri Carbonatis, U. S. P. 

Ferrous carbonate is said to be more easily dissolved in the stom- 
ach than any other iron preparation. It is so unstable and prone to 
oxidation, that it must be washed in water containing no dissolved 
air and niixed with the sugar (which protects it from oxidation) as 
quickly as possible. In making the official compound mixture of 
iron (Mistura Ferri Composita, U. S. P.), " Griffith's mixture," the 
various ingredients, including the carbonate of potassium, should 
be placed in a bottle of the required size, space being left for 
the crystals or solution of ferrous sulphate, which should be 
added last, the bottle immediately filled up with the rose-water, 
and securely corked ; the minimum of oxidation is thus insured. 
More than 2 molecular weights of the carbonate of potassium to 1 
of the sulphate of iron are ordered in the official mixture ; hence, as 
the ferrous carbonate decomposes, the carbonic acid produced does 
not necessarily escape, but converts carbonate into bicarbonate of 
potassium. Fihdce Ferri Compositce, U. S. P., is made from myrrh, 
carbonate of soda, sulphate of iron, and syrup: carbonate of iron 
is gradually formed. 

FeS0 4 + K 2 C0 3 = FeC0 3 + K 2 S0 4 

Ferrous Carbonate of Ferrous Sulphate of 

sulphate. potassium. carbonate. potassium. 

Arseniate of Iron. Ferrous Arseniate. 
Third Synthetical Reaction^ by which the lower arseniate 
of iron, ferrous arseniate {Ferri Arsatias, B. P.) (Fe s 2As0 4 )j 
partially oxidized, is formed. This will be noticed again under 



144 THE METALLIC RADICALS. 

partially oxidized, is formed. This will be noticed again under 
Arsenicum. 

Phosphates of Iron. a. Ferrous Phosphate. 

Fourth Synthetical Reaction. — To a hot solution of ferrous 
sulphate in a test-tube add a hot solution of phosphate of so- 
dium and a little of a solution of bicarbonate of sodium ; the 
lower phosphate of iron, ferrous phosphate (Fe 3 2P0 4 ) is pre- 
cipitated (Ferris Phosphas, B. P.). 

3FeS0 4 + 2Na 2 HP0 4 -f- 2NaHC0 3 

Ferrous Phosphate of Bicarbonate 

sulphate. sodium. of sodium. 

= Fe^PO, + 3Na 2 S0 4 + 2H 2 + 2C0 2 

Ferrous Sulphate of Water. Carbonic 

phosphate. sodium. acid gas. 

Officially, solutions of 3 ounces of sulphate of iron in 30 of hot 
water and 2| ounces of phosphate in 30 of hot water, together with 
| of an ounce of bicarbonate of sodium dissolved in a little water, 
are well mixed, filtered, the precipitate well washed with hot water, 
and, to prevent oxidation as much as possible, dried at a tempera- 
ture not exceeding 120° F. These proportions will be found to fairly 
accord with the molecular weights of the crystalline salts, multi- 
plied as indicated in the foregoing equation. 3(FeS0 4 ,7H 2 0) = 834 ; 
2(Xa 2 HP0 4 ,12H 2 0) = 716 ; 2(XaHC0 3 ) = 168. 

The above reaction also occurs in making Syrupus Ferri Phos- 
phatis, B. P. 

The use of bicarbonate of sodium is to ensure the absence of free 
sulphuric acid in the solution. Sulphuric acid is a powerful solvent 
of ferrous phosphate. It is impossible to prevent the separation 
of sulphuric acid if only ferrous sulphate and phosphate of sodium 
be employed. Ferrous phosphate is white, but soon oxidizes and 
becomes slate-blue. The official salt contains at least 47 per cent, of 
hydrous ferrous phosphate, Fe 3 (P0 4 ) 2 (H 2 0) g , with ferric phosphate 
and some oxide. 

b. Ferric phosphate (see page 153). 

Sulphide of Iron. Ferrous Sulphide. 

Fifth Synthetical Reaction. — In a gas- or spirit-flame strongly 
heat sulphur with about twice its weight of iron filings in a 
test-tube (or in an earthen crucible in a furnace) ; ferrous sul- 
phide (FeS) is formed. When cold, add water to a small por- 
tion, and then a few drops of sulphuric acid; sulphuretted 
hydrogen gas (H 2 S), known by its odor, is evolved. 

FeS + H 2 SO, = FeSO, + H 2 S. 

Sticks of sulphur pressed against a white-hot bar of cast iron give 
a pure form of ferrous sulphide. The liquid sulphide thus formed 



IRON. 145 

is allowed to drop into a vessel of water. Or melted sulphur may 
be poured into a crucible full of red-hot iron nails, when a quantity 
of fluid ferrous sulphide is at once formed, and may be poured out 
on to a slab. 

Green Iodide of Iron. Ferrous Iodide. 

Sixth Synthetical Reaction. — -Place a piece of iodine, about 
the size of a pea, in a test-tube with a small quantity of water, 
and add a few iron filings, small nails, or iron wire. On gently 
warming, or merely shaking if longer time be allowed, the 
iodine disappears, and, on filtering, a clear light-green solution 
of iodide of iron (Fel 2 ) is obtained. On evaporation solid 
iodide remains. 

Solid iodide of iron contains about 18 per cent, of water of crys- 
tallization, and a little oxide of iron. It is deliquescent and liable 
to absorb oxygen from the air, with formation of insoluble ferric 
oxyiodide or hydrato-iodide. Iodide of iron thus spoiled may be 
purified by re-solution in water, addition of a little more iodine and 
some iron, warming, filtering, and evaporating as before. Syrup 
of Iodide of Iron which has become brown may usually be restored 
by immersing the bottle in a water-bath and slowly warming. 

Ferrous bromide (FeBr 2 ), occasionally used in medicine, could be 
made, as might be expected, in the same way as the iodide. Syrupus 
Ferri Bromidi, U. S. P., contains 10 per cent, of ferrous bromide. 

Ferri Iodidum Saccharatum, U. S. P., is made by mixing 6 parts 
of iron, 17 of iodine, and 20 of water, snaking until reaction ceases, 
filtering 4nto 40 parts of sugar of milk, evaporating to dryness 
with frequent stirring, and mixing the product in a mortar with 
20 additional parts of sugar of milk. It is a grayish or yellowish- 
white hygroscopic powder. 

Syrupus Ferri Iodidum, U. S. P., contains 10 per cent, of the 
iodide. 

FERRIC SALTS. 
Anhydrous Perchloride of Iron. Ferric Chloride. 
Seventh Synthetical Reaction. — Pass chlorine (generated as 
usual from black oxide of manganese and hydrochloric acid in 
a flask) through sulphuric acid contained in a small bottle, and 
thence by the ordinary narrow glass tubing quite to the bottom 
of a test-tube containing twenty or thirty small iron tacks (or 
a Florence flask containing 2 or 3 ounces of iron tacks), the 
latter kept hot by a gas-flame ; the higher chloride of iron, 
ferric chloride, or the perchloride* of iron (Fe a Cl 6 ), is formed, 
and condenses in the upper part of the tube or flask as a mass 

* The prefixes per and hyper used here and elsewhere are from inrip\ 

lii/pcr, over and above, and .simply mean "the highest " of several. 
Thus perchloride, the highest chloride. 



146 TIIE METALLIC RADICALS. 

of small dark, iridescent crystals. When a tolerably thick crust 
of the salt is formed, break off the part of the glass containing 
it, being careful that the remaining corroded tacks are ex- 
cluded, and place it in ten or twenty times its weight of water; 
the resulting solution, poured off from any pieces of glass, is a 
Fig. 31. 




Preparation of Anhydrous Ferric Chloride. 

pure neutral solution of hydrous ferric chloride, and will be 
serviceable in performing analytical reactions. 

Precaution. — The above experiment must be conducted in the open 
air, or in a cupboard having a draught outwards. 

Anhydrous Ferrous Chloride. — In breaking up the tube, small 
scales of a light buff color will be observed adhering to the nails ; 
they are crystals of ferrous chloride (FeCl 2 ). 

Note. — Solution of ferric chloride evolves some hydrochloric acid on 
boiling, while a darker colored solution of ferric oxychloride remains. 

Formula of Ferric Chloride. — Qualitative analysis shows that 
ferric chloride contains iron and chlorine. Quantitative analysis 
shows that to 56 parts of iron there are 106.5 parts of chlorine ; 
total, 162.5. And as 56 parts of iron are indicated by the symbol 
Fe, and 162.5 of chlorine by the symbol and figure Cl 3 , the formula 
for ferric chloride will, so far, be FeCl 3 . But equal volumes of 
gases and vapors contain equal numbers of molecules (see p. 53). 
A volume which, if water-vapor, weighs 18 grains, will, if ammonia, 
weigh 17 grains, or if carbonic acid gas, 44 grains, and if perchlo- 
ride of iron vapor, 325 grains. And these respective volumes con- 
taining equal numbers of molecules, one molecule of each will be 
represented by the same figures respectively ; that is to say, the 
equal volumes differing in weight as the figures 18, 17, 44, and 325 
differ •, and the volumes containing equal numbers of molecules, the 
respective molecules themselves will differ in weight as the figures 
18, 17, 44, and 325 differ. Now, 325 parts by weight of perchloride 
of iron can only be represented by the formula Fe 2 Cl 6 ; for FeCl 3 



IRON. 147 

would only represent half the number thus obtained by actual 
experiment. Hence Fe 2 Cl 6 is the formula for a molecule of perchlo- 
ride of iron, and not FeCl 3 — at all events, at temperatures between 
320° and 440° C. 

Green Chloride of Iron. Hydrous Ferrous Chloride. Solution 
of Hydrous Ferric Chloride. 

Eighth Synthetical Reaction. — Dissolve iron tacks, in a test- 
tube, in hydrochloric acid ; hydrogen escapes, and the solution 
on cooling, or on evaporation and cooling, deposits crystallized 
ferrous chloride (FeCl 2 ), associated with four molecules of 
water (4H 2 0) of crystallization (FeCl 2 ,4H 2 0). 

Through a portion of the solution of ferrous chloride pass 
chlorine gas ; the ferrous chloride becomes ferric chloride. 

The excess of chlorine dissolved by the liquid in this experiment 
may be removed by ebullition ; but the ferric chloride is liable to be 
slightly decomposed. The free chlorine is better carried off by pass- 
ing a current of air through the liquid for some time. 

Hydrous Ferric Chloride (another process). 

Ninth Synthetical Reaction. — To another portion of the solu- 
tion of ferrous chloride, in a test-tube, add a little hydrochloric 
acid ; heat the liquid, and continue to drop in nitric acid until 
the black color it first produces disappears ; the resulting red- 
dish-brown liquid is solution of ferric chloride. 
6FeCl 2 ± 2HN0 3 + 6HC1 = 3Fe a Cl 6 + 2NO + 4H 2 

Ferrous Nitric Hydrochloric Ferric Nitric Water, 

chloride. acid. acid. chloride. oxide. 

The black substance is a compound of nitric oxide gas (NO) with 
a portion of the ferrous salt ; it is decomposed by heat. 

This is the process for producing the Liquor Ferri Chloridi, U. S. 
P., definite weights of materials being employed and the solution 
of ferrous chloride being poured slowly into the nitric acid. The 
sp. gr. of the Liquor is 1.405. It contains some free hydrochloric 
acid. Percentage of anhydrous chloride, 37.8. 

35 parts of this solution and 65 of alcohol form the Tinctura Ferri 
Chloridi, U. S. P. 

Note. — The spirit in the tincture is unnecessary, useless, and dele- 
terious ; for it acts neither as a special solvent nor as a preservative, 
the offices usually performed by alcohol (Tinctura? ct Sued, 1>. P. 
and U. S. P.), but, unless the liquid contain excess of acid, decom- 
poses the ferric chloride and causes the formation of an insoluble 
oxychloride of iron. Even if the tincture be acid, it slowly loses 
color, ferrous chloride and chlorinated ethereal bodies being formed. 
A Liquor, of similar strength, is doubtless destined to displace the 
tincture altogether. 

A strong solution of ferric chloride, on standing, yields a mass oi' 
yellow crystals {Ferri Chhridum, U. S. P.) containing 1«Y,,01,., L2H a O, 
or, rarely, red crystals having the formula Fe.,C l 6 ,5 11. ,0. 



148 THE METALLIC RADICALS. 

Persulphate of Iron. Ferric Sulphate. 

Tenth Synthetical Reaction. — Dissolve ferrous sulphate with 
about a fifth of its weight of sulphuric acid in water in an 
evaporating-dish, heat the mixture and drop in nitric acid until 
the black color it first produces disappears ; the resulting liquid, 
when made of a certain prescribed strength, is the solution 
of ferric sulphate, or higher sulphate, " Solution of Tersul- 
phate of Iron " of the Pharmacopoeia, a heavy dark-red liquid, 
sp. gr. 1.320 (Liquor Ferri TersuZphatis, U. S. P.). Liquor 
Ferri Svbsulphatix, U. S. P. (Monsel's Solution), is a similar 
fluid, made with less acids, containing, therefore, ferric oxy- 
sulphate, Fe 4 05S0 4 (sp. gr. 1.555). 
6FeS0 4 + 3HS0 4 + 2HN0 3 = 3(Fe 2 3S0 4 ) + 2X0 + 4H 2 

Ferrous Sulphuric Nitric Ferric Nitric Water. 

sulphate. acid. acid. sulphate. oxide. 

The black color, as in the previous reaction, is due to a compound 
of ferrous salt with nitric oxide (2FeS0 4 — NO). 

Note. — In all the reactions in which iron passes from ferrous to 
ferric condition the element assumes different properties, the chief 
one being an alteration from bivalent to trivalent activity. 

The official " Solution of Normal Ferric Sulphate" or Tersulphate, 
just mentioned, is made by heating a mixture of 15 parts of sul- 
phuric acid, 11 of nitric, and 50 of water, and adding 80 of ferrous 
sulphate (about one-fourth at a time) ; then dropping in more nitric 
acid until red fumes cease to be produced and heating until the fluid 
has a reddish-brown color and is free from nitrous odor. "Water is 
added to make 200 parts. It contains 28.7 per cent, of anlrydrous 
ferric sulphate. 

Acetate of Iron. Ferric Acetate. 
Eleventh Synthetical Reaction. — Digest recently washed and 
drained ferric hydrate in glacial acetic acid ; ferric acetate, 
Fe 2 6C 2 H 3 Q 2 , is produced. 

Fe 2 6HO + 6HCAO, = Fe 2 6C 2 H 3 2 + 6H 2 

Ferric hydrate. Acetic acid. Ferric acetate. Water. 

The Solution of Acetate of Iron {Liquor Ferri Acetatis, IT. S. P.) 
is an aqueous solution of ferric acetate, containing 33 per cent, of 
Fe 2 6C 2 H 3 2 . It is made by dissolving the ferric hydrate prepared 
from a known quantity of ferric sulphate in a definite weight of gla- 
cial acetic acid. Sp. gr. 1.160. 5(J parts of this solution, 30 of al- 
cohol, and 20 of acetic ether form the Tinctura Ferri Acetatis, U. S. P. 

Ferric Oxyhydrate, or Hydrated Oxide of Iron. 
Twelfth Synthetical Reaction. — Pour a portion of the solution 
of ferric sulphate into excess of solution of ammonia; moist 
ferric hydrate, Fe 2 CHO, is precipitated (Ferri Oxidum Hijdra- 
tum, U. S. P.). 



IRON. 149 

Fe 2 3S0 4 + 6AmH0 == Fe 2 6HO + 3Am 2 S0 4 

Ferric Ammonia. Ferric Sulphate 

sulphate. hydrate. of ammonium. 

Wash the precipitate by decantation or on a filter, and dry it on a 
plate over boiling water ; ferric oxyhydrate, Fe 2 2 (HO). 2 {Ferri per- 
oxidum hydratum, B. P.), remains. When rubbed to a fine powder 
it is fit for medicinal use. 

Fe 2 CHO = Fe 2 2 (OH) 2 + 2H 2 

Ferric hydrate. Ferric oxyhydrate. Water. 

Either of the other alkalies (potash or soda) will produce a similar 
reaction ; soda is cheapest, ammonia most convenient. 

Ferric hydrate is an antidote to arsenic if administered directly 
the poison has been taken. 

It converts the soluble arsenic (As 2 3 ) into insoluble ferrous 
arseniate : — 

2(Fe. 2 6HO) + As 2 3 == Fe 3 2As0 4 + 5H 2 + Fe2HO. 

Dried ferric hydrate (having become an oxyhydrate — Fe 4 4 4HO) has 
less action on arsenic. Even the moist, recently prepared hydrate 
(Fe 2 6HO) loses much of this power as soon as it has become con- 
verted into an oxyhydrate (Fe 4 3 6HO), a change which occurs though 
the hydrate be kept under water (W. Procter, Jr.). According to 
T. and H. Smith this decomposition occurs gradually, but in an in- 
creasing ratio ; so that after four months the power of the moist 
mass is reduced to one-half and after five months to one-fourth. 
Now mere loss of water is not usually followed by any alteration 
of the essential chemical properties of a compound. It would seem, 
therefore", that ferric hydrate (two molecules) (Fe 4 12HO) probably 
suffers, on standing, actual decomposition into oxyhydrate (Fe 4 3 6HO) 
and water (3H 2 0), and does not merely lose water already existing 
in it as water. Ferric hydrate is also far more readily soluble in 
hydrochloric acid, tartaric acid, citric acid, and acid tartrate of 
potassium, than ferric oxyhydrate. Any formula exhibiting ferric 
hydrate (Fe 2 6IIO) as a combination of ferric oxide and water 
(Fe 2 3 ,3H 2 0), or the oxyhydrate (Fe 2 2 ,2IIO) as a similar combina- 
tion (Fe 2 3 ,H 2 0) are apparently, for these and other reasons, 
scarcely correct. 

Ferri Oxidum Hydration cum Magnesia. — As a more trustworthy 
arsenical antidote, a mixture of solution of ferric sulphate and mag- 
nesia is recommended in the United States Pharmacopoeia. Bottles 
containing (a) 100 parts of the official solution of ferric sulphate 
mixed with twice its weight of water, and (/>) lf> parts of magnesia 
well mixed and diluted with water, are to be kept on hand ready 
for immediate use. Their contents are simply mixed, shaken to- 
gether, and administered to the patient. 

Fe 2 3S0 4 + 3MgO + 3H 2 = 3MgSO< I VcjWlO 
Ferric Magnesia. Water. Sulphate of Ferric 

sulphate. magnesium. hydrate. 



150 THE METALLIC RADICALS. 

Peroxide of Iron. Ferric Oxide. 

The six univalent atoms of the HO, the characteristic elements of 
all hydrates, are thus, by two successive steps, split up into water 
and oxygen. But between the hydrate and oxide there obviously 
may be another oxyhydrate, in which only 2HO is displaced by // , 
and such a compound is well known ; it is a variety of broAvn iron 
ore. The other oxylrydrate, Fe 2 2 2IIO, is also native (needle iron 
ore), as well as being the Ferri Peroxidum Hydration, B. P. 

"Ferri Peroxidum Humidum 1 ' Fe"^ 6IIO 

A variety of brown iron ore Fe /// 2 // 4HO 

"Ferri Peroxidum Hydratum " (needle ore) . . Fe'^O'^HO 

Ferric oxide Ye /// 2 // s 

The moist ferric hydrate, as already stated, when kept for some 
months, even under water, loses the elements of water, and is 
converted into an oxyhydrate having the formula Fe 4 H 6 9 (iinio- 
nite or brown haematite), which is either a compound of the above 
oxvhydrates (Fe 2 04HO) + (Fe 2 2 2IIO), or is a definite intermediate 
oxyhydrate (Fe 4 O s 6HO). 

By ebullition with water for seven or eight hours, ferric hydrate 
is decomposed into water and an oxyhydrate having the formula 
Fe 4 H 2 7 (Saint Giles), which is either a mixture of the official 
oxyhydrate (Fe 2 2 2HO) with ferric oxide (Fe 2 3 ), or a definite in- 
termediate body (Fe 4 5 2IIO). The relation of these bodies to each 
other will be apparent from the following Table, in which, for con- 
venience, the formulas of ferric hydrate and oxide are doubled : — 

Ferric hydrate (B. P.) (as stalactite) . . . . Fe 4 12HO 

Kilbride mineral (?) Fe.OlOHO 

Brown iron ore (Huttenrode and Raschau) . . Fe 4 2 8HO 

Old, or frozen, ferric hydrate (limonite) . . . Fe 4 3 6HO 

Ferric oxyhydrate (B. P.) (gothite) .... Fe 4 4 4HO 

Boiled ferric hydrate (turgite) Fe 4 5 2H0 

Ferric oxide (red haematite) Fe 4 6 

A ferric oxycarbhyclrate (Fe 4 OC0 3 8HO) has been obtained by 
Rother. 

The English official ferric oxyhydrate (Fe 2 2 2HO) was formerly 
made by mixing solutions of ferrous sulphate and carbonate of 
sodium, and exposing the resulting ferrous carbonate to the air until 
it was nearly all converted into ferric oxyhydrate ; hence its old 
names, still sometimes seen on old bottles, of Ferri Carbonas and 
Ferri Subcarbonas. 

Ferric Oxide (another process). 
Thirteenth Synthetical Reaction. — Roast a crystal or two of 
ferrous sulphate in a small crucible until fumes cease to be 
evolved ; the residue is a variety of ferric oxide (Fe 2 3 ) or 
peroxide of iron, known in trade as red oxide of iron, colcothar, 
crocus, roucje (mineral), or Venetian red. It has sometimes 
been used in pharmacy in mistake for the official oxyliydrates 



IRON. 151 

(vide 12th Synthet. Reac), from which it differs not only in 
composition, but in the important respect of being almost in- 
soluble in acids. 

The Scale Compounds of Iron. 

Fourteenth Synthetical Reaction. — Repeat the twelfth reac- 
tion, introducing a little solution of citric or tartaric acid, or 
acid tartrate of potassium, before adding to the alkali (soda, 
potash, or ammonia), and notice that now no precipitation of 
ferric hydrate occurs. This experiment serves to illustrate, not 
the manufacture of a scale compound, but the chemistry of the 
manufacture. The effect is due to the formation of double 
compounds, termed Ammonio-Citrate, Potassio-Citrate, Am- 
monio-Tartrate, Potassio-Tartrate, and similar Sodium com- 
pounds of Iron, which remain in solution along with the second- 
ary product — sulphate of the alkali metal. Such ferric com- 
pounds, made with certain prescribed proportions of recently 
prepared ferric hydrate (from which all alkaline sulphate has 
been washed), and the respective acids (tartaric or citric) or 
acid salts (acid tartrate of potassium), etc., and the solutions 
evaporated to a syrupy consistence, and spread on flat plates 
till dry, form the scale preparations known as Ferri et Ammo- 
nii Citras, U. S. P., Ferri Oitras, U. S. P. (also Liquor Fern 
Citratis, U. S. P.), Ferri et Ammonii Tartras, U. S. P., and 
Ferri Fotassio-tartras, or rather Ferritin Tartaratum, B. P., 
Ferri et Potassii Tartras, U. S. P. A mixture of citrate of 
iron and ammonium with citrate of strychnine yields, on evap- 
oration, Ferri et Strychnin se Citras, U. S. P. A mixture of 
ferric citrate with citrate of ammonium and citrate of quinine 
yields, by similar treatment, the well-known scales of Fori et 
Quinhise Gitrqs, U. S. P. 

Specimens of these substances may be prepared by attending 
to the following details. It is essential, first, that the ferric 
hydrate be thoroughly washed, or an insoluble oxysulphate will 
be formed ; second, that the ferric hydrate be rapidly washed, 
or an insoluble ferric oxyhydrate will be produced; thirdly, 
that the whole operation be conducted quickly, or reduction to 
green ferrous salt will occur ; fourthly, that the solutions of the 
salts be not evaporated at a higher temperature than that stated, 
or decomposition will take place; and fifthly, that the Pull 
quantities of ferric hydrate be employed. 

In the pharmacopoeia! processes for the scale compounds, the ferric 
hydrate is in each case freshly made from solution of ferric sulphate 
l>v precipitation with solution of ammonia, 



152 THE METALLIC RADICALS. 

Fe 2 3S0 4 + 6AmH0 = Fe 2 6HO + 3Am 2 S0 4 

Ferric Hydrate of Ferric Sulphate of 

sulphate. ammonium. hydrate. ammonium. 

the solution of ferric sulphate being made of a definite strength (see 
p. 146) from a known weight of ferrous sulphate. The reason for 
adopting this course is that ferric hydrate is unstable and cannot be 
weighed, because it cannot be dried without decomposing and be- 
coming insoluble, as explained under the 12th reaction. 

Ferri Citras, U. S. P., and Ferri et Ammonii Citras, U. S. P. — 
Ferric hydrate is dissolved in solution of citric acid, and the whole 
evaporated to dryness without or with ammonia. 

To prepare the ferric hydrate, dilute 105 parts of official solution 
of ferric sulphate with water ; pour this into water containing excess 
of solution of ammonia. (If the opposite course were adopted, the 
alkaline liquid poured into the ferric solution, the precipitate would 
contain ferric oxysulphate, or hydrato-sulphate, which interferes 
with the brilliancy of the scales.) Thoroughly stir the mixture (it 
will smell strongly of ammonia, if enough of the latter has been 
added), allow the precipitate to subside, pour away the supernatant 
liquid, add more water, and repeat the washing until a little of the 
liquid tested for by-product (sulphate of ammonium) by solution of 
chloride or nitrate of barium ceases to give a white precipitate (sul- 
phate of barium). Collect the ferric hydrate on a filter, drain, and 
place in it, while still moist, 30 parts of citric acid, in an evaporat- 
ing-basin, over a water-bath ; stir frequently, until the hydrate has 
dissolved. Filter, and either evaporate until the liquid weighs 100 
parts (Liquor Ferri Citratis, U. S. P., sp. gr. 1.260; strength, 35.5 
per cent, of Fe 2 2C 6 H 5 7 ) or evaporate to a syrup at 60° C. and spread 
on glass plates to dry (Ferri Citras, U. S. P., Fe 2 2C 6 H 5 7 ,6H 2 0), or 
to 3 parts of the Liquor add 1 of ammonia-water and evaporate to 
form scales (Ferri et Ammonii Citras, U. S. P.). 

Ferri et Quinince Citras, U. S. P., is made by dissolving 12 parts 
of pure quinine (dried at 100° C.) and 88 parts of citrate of iron in 
water, evaporating and scaling. Liquor Ferri et Quinince Citratis. 
U. S. P., contains citrate of iron and ammonium and citrate of qui- 
nine. 

Ferri et Strychnines Citras, U. S. P., is prepared by mixing one 
part of strychnine and one of citric acid with a solution containing 
98 parts of citrate of iron and ammonium, evaporating the mixture 
at a temperature not exceeding 60° C. or 140° F. to a syrupy con- 
sistence, and scaling in the usual way by spreading it upon plates 
of glass. 

Ferri et Potassii Tartras, U. S. P. — Ferric hydrate is dissolved in 
solution of acid tartrate of potassium with a little ammonia, and 
the whole evaporated to dryness. 

The ferric hydrate obtainable from twelve parts of the official 
solution of ferric sulphate by the action of ammonia, in the manner 
detailed in the previous paragraphs, is mixed (in a mortar), while 
still moist but well drained, with four parts of acid tartrate of potas- 
sium. The whole is then heated in a dish over a water-bath to a 
temperature not exceeding 140° F., and the mixture kept warm 



IRON. 1 53 

until nothing more will dissolve ; a little ammonia added and the 
clear fluid evaporated at a temperature not exceeding 140° F. 
(greater heat causes decomposition), and, when the mixture has 
the consistence of syrup, spread on panes of glass and allowed to 
dry (in any warm and open place shown by a thermometer to be 
not hotter than 140° F.). The dry salt is then obtained in flakes. 
It should be kept in well-closed bottles. 

Ferri et Ammonii Tartras, U. S. P., is made by saturating solu- 
tion of acid tartrate of ammonium with ferric hydrate, evaporating, 
and scaling. The acid tartrate is prepared by exactly neutralizing 
half of any quantity of tartaric acid by carbonate of ammonium, 
and then adding the other half. 

The foregoing are the only official scale preparations of iron. 
Many others of similar character might be formed. The Citrate 
dissolves slowly in cold but readily in warm water. Few crystal- 
lize or give other indications of definite chemical composition. 
Their properties are only constant so long as they are made with 
unvarying proportions of constituents. Want of chemical com- 
pactness, the loose state in which the iron is combined, precludes! 
their recognition as well-defined chemical compounds, yet possibly 
enables them to be more readily assimilated as medicines than some 
of the more definite ferrous and ferric salts. 

A definite ferrous tartrate (FeC 4 H 4 6 ) and ferrous citrate 
(FeHC 6 H 5 7 ,H 2 0) have been obtained by, reaction of iron and 
acid in hot water. They occur as white masses of microscopic 
crystals. A sodio-ferrous citrate (FeNaC II 5 O 7 ) and hi/drato-cifra/e 
(FeNa 2 HOC 6 H 5 7 ) may be obtained in scales (Rother). 

Ferric phosphate (Fe 2 2P0 4 ), when freshly precipitated, is soluble 
in solution of citrates of the alkali-metals, and the mixture, on 
evaporation on glass plates, yields scales. The official (U. S. P.) 
Ferri Phosphas is to be made by adding G parts of phosphate of 
sodium to an aqueous solution of 5 parts of citrate of iron, evap- 
orating and scaling. It is a mixture of ferric phosphate and citrate 
of sodium. 

Wine of Iron, or "Steel" wine {Vinum Ferri, B. P.), made by 
digesting iron wire in sherry wine, probably contains tartrate of 
potassium and iron and other iron salts, formed by action of the 
metal on the acid tartrate of potassium and tartaric, citric, malic, 
and acetic acid present in the wine. Vinum, Ferri Citratis, U. S. P., 
contains ammonio -citrate of iron ; Vinum Ferri Aniarum, U. S. P., 
contains citrate of iron and quinine. 

Black Hydrate of Iron. Ferroso-ferric Hydrate. 

Fifteenth Synthetical Reaction. — To two-thirds of a small 
quantity of a solution of ferrous sulphate add a little sulphuric 
acid; warm, and gradually add nitric acid, as described in the 
tenth reaction, care being taken not to allow one drop more 
nitric acid than necessary to fall into the test-tube. Add the 
other third of ferrous sulphate, snake, and pour t ho liquid into 



154 THE METALLIC RADICALS. 

excess of an alkali ; black (at first brown) hydrate of iron, or 
ferroso-ferric hydrate (Fe 3 8HO = Fe2HO,Fe 2 6HO), is pro- 
duced. 

Fe 2 3SO, + FeS0 4 + 8NaHO = Fe 3 8HO + 4Na 2 S0 4 

Ferric Ferrous Soda. Blk. Hydrate Sulphate 

sulphate. sulphate. of iron. of sodium. 

It is so readily attracted by a magnet, even when moist, as to 
collect round the poles when the instrument is immersed in 
the supernatant liquid. Hence the name, magnetic oxide of iron. 

In this process the nitric acid oxidizes the hydrogen of the sul- 
phuric acid, the sulphuric radical uniting with the ferrous sulphate, 
the iron of which is at the same time altered from the ferrous to the 
ferric condition, ferric sulphate being formed. If too much nitric 
acid be employed, the second portion of ferrous sulphate will also 
be converted into ferric salt, and the solution, on the addition of 
alkali, yield only red ferric hydrate. This result may be avoided 
by evaporating the solution of ferric sulphate nearly to dryness, 
thus boiling off excess of nitric acid, or by pouring first the ferric 
and then the ferrous liquid into the alkali and thoroughly stirring 
the mixture ; any nitric acid is then neutralized and rendered in- 
capable of oxidizing the ferrous sulphate subsequently added. 

Black hydrate of iron is decomposed by heat, yielding, in a closed 
vessel, oxy hydrates, and, finally, black oxide of iron or ferroso-ferric 
oxide. Heated in the air it absorbs oxygen and gives ferric oxide. 
The black forge-scales which collect near the blacksmith's anvil 
have the composition of ferroso-ferric oxide : the black magma 
formed on exposing a mixture of iron and water to the air is fer- 
roso-ferric hydrate ; but these varieties are apt to contain particles 
of metal, and hence give hydrogen gas when dissolved in acids — a 
character which distinguishes them from the medicinal preparation. 

If a dried specimen of the black hydrate of iron be required, the 
mixture should be well boiled and then set aside for an hour or two 
to favor aggregation of the particles, the mixture filtered, and the 

f>recipitate washed until the washings contain no trace of sulphate 
that is, until they no longer yield a white precipitate with chloride 
of barium). Black hydrate of iron absorbs oxygen even at the 
temperature of the water-bath ; it should consequently be dried at 
120°, a temperature at which only slight oxidation occurs. 

Pernitrate of Iron. Ferric Nitrate. 

Sixteenth Synthetical Reaction. — Place a few iron tacks in 
dilute nitric acid and set aside ; solution of ferric nitrate, or 
pernitrate of iron, is formed (Fe 2 6N0 3 ). 

Fe 2 + 8HN0 3 == Fe a 6N0 8 + 4H 2 -f 2NO 

Iron. Nitric acid. Ferric nitrate. Water. Nitric oxide. 

Precipitate ferric hydrate from solution of ferric sulphate, 
wash, and dissolve it in nitric acid. 



155 



Fe. 2 6HO + 

Ferric hydrate. 



6HN0 8 

Nitric acid. 



Fe 2 6N0 3 

Ferric nitrate. 



6H 2 

Water. 



The latter is the official method for preparing Liquor Ferri Nitra- 
tis, U. S. P., definite quantities of solution of ferric sulphate and of 
nitric acid being employed. Sp. gr. 1.050. Strength, about 6 per 
cent, of anhydrous nitrate. 

Ferric nitrate and ferric acetate unite to form various aceto-nitrates, 
amongst which is one having the formula Fe 2 (C 2 H 3 0) 4 N0 3 ,HO,4II 2 0, 
crystallizing in hard, shining, brownish-red prisms. 



Reduced Iron. 

Seventeenth Synthetical Reaction. — Pass hydrogen gas (dried 
by passing over pieces of chloride of calcium contained in a 

Fig. 32. 




Preparation of Reduced Iron. 

tube, or through sulphuric acid in a wash-bottle) into a small 
quantity of ferric oxyhydrate (" subcarbonate," U. S. P.) con- 
tained in a tube arranged horizontally (a test-tube the bottom 
of which has been accidentally broken answers very well), the 
oxyhydrate being kept hot by a gas-flame ; oxygen is removed 
by the hydrogen, steam escapes at the open end of the tube, and 
after a short time, when moisture ceases to be evolved, metallic 
iron, in a minute state of division, remains. (See Fig. 32.) 

Fe,0 3 + 3H 2 = Fe 2 + 3H 2 

Ferric oxide. Hydrogen. Iron. Water. 

While still hot throw the iron out into the air; it takes fire 
and falls to the ground as oxide. 

If the ferric oxide is reduced in an iron tube heated by a strong 
furnace, the particles of iron aggregate to some extent, and, when 
cold, are only slowly oxidized in dry air. This latter form of re- 



156 THE METALLIC RADICALS. 

duced iron is Fer reduit or Quevennes Iron, the ferri pulvis, or Fer- 
ritin Reduction, U. S. P. — "a fine grayish-black powder, strongly 
attracted by the magnet, and exhibiting metallic streaks when rubbed 
with firm pressure in a mortar." 

Kate I. — The spontaneous ignition of the iron in the above experi- 
ment is an illustration of the influence of minute division on chemi- 
cal affinity. The action is the same as occurs whenever iron rusts, 
and the heat evolved and amount of oxide formed is not greater 
from a given quantity of iron ; but the surface exposed to the action 
of the oxygen of the air is, in the case of this variety of reduced 
iron, so enormous compared with the Aveight of the iron, that heat 
cannot be conducted away sufficiently fast to prevent elevation of 
temperature to a point at which the whole becomes incandescent. 
In the slow rusting of iron escape of heat occurs, but is not ob- 
served, because spread over a length of time ; in the spontaneous 
ignition of reduced iron the whole is evolved at one moment. The 
mixture of lead and carbon (lead pyrophorus) resulting when tartrate 
of lead is heated in a test-tube until fumes cease to be evolved, spon- 
taneously ignites when thrown into the air, and for the same reason. 
Many substances, solid and liquid, if sufficiently finely divided and 
liable to oxidation, and especially if exposed in a warm place, be- 
come hot, and even occasionally spontaneously burst into flame. 
Oil on cotton-waste, powdered charcoal, coal, especially if pyritic 
or if very porous, or if powdered, resins in powder, and even flour, 
are familiar illustrations of materials liable to " heat" or even burn 
spontaneously. 

Note II. — The student having time and opportunity for the 
experiment is advised to make this seventeenth reaction a 
roughly quantitative one, by way of realizing what has been 
stated (see, again, the General Principles of Chemical Phil- 
osophy, pp. 36-59) respecting the action of chemical force on 
definite weights only of matter. Three tubes, similar to the 
oxide-tube shown in the engraving, should be prepared, the 
second being connected to the first and the third to the second 
by India-rubber tubing in the usual manner. The first tube 
should contain pieces of chloride of calcium to absorb any 
traces of moisture not retained by the sulphuric acid. The 
second tube (the ends of the small tube being temporarily 
closed by small corks) should be weighed in any ordinary 
scales which will turn with a quarter or half of a grain, and, 
the weight being noted, 160 grains of dry ferric oxide should 
be neatly placed in the middle of the tube. (The oxide must 
be previously gently heated in a small crucible over a lamp to 
remove all traces of moisture.) The third tube should contain 
pieces of chloride of calcium to absorb the water produced in 
the reaction, and just before being connected should be weighed. 
The operation is now carried out. At its close, and when the 
middle tube is cold, the latter tube and the third tube are again 



IRON. 157 

weighed. The oxide-tube should weigh 48 grains less than 
before, and the terminal tube 54 grains more than before. 

FeA + 3H 2 = Fe 2 + 3H 2 

112 + 48 = 160 6 112 54 

The operation is more quickly and easily performed if one-half 
or one-quarter of the weight of oxide be taken ; in that case 
one-half or one-quarter of the weight of iron and of water will 
be obtained. Indeed any weight of oxide may be employed ; 
the amount of iron and water resulting will be always, exactly 
'proportionate to the weights just mentioned. Thus 16 parts 
of oxide yield 11.2 of iron and 5.4 of water. Iron, hydrogen, 
and oxygen always combine in proportions of 56, 1, and 16 
respectively ; hence our justification for agreeing that the sym- 
bol Fe shall stand for 56, more exactly 55.9, parts by weight 
of iron, H for 1 part by weight of hydrogen, and fur 1G parts 
by weight of oxygen. 

Ferric Pyrophosphate. 

Eighteenth Synthetical Reaction. — To solution of pyrophos- 
phate of sodium add solution of ferric sulphate ; a yellowish- 
white precipitate of ferric pyrophosphate (Fe 4 3P 2 7 ,9H 2 0)' 
separates. 

The official (U. S. P.) Ferri Pyrophosphate is to be made by 
adding 10 parts of pyrophosphate of sodium to an aqueous solu- 
tion of 9 parts of citrate of iron, evaporating and scaling. The 
apple-green product is a mixture of ferric pyrophosphate and 
citrate of sodium. 

Dialyzed Iron. 

"Liquor Ferri Dialysatus" B. P. — This solution of Dialyzed 

Iron, so called, is a solution of highly basic ferric oxychloride 

or chloroxide of iron, from which most of the acidulous matter 

has been removed by dialysis. Vide " Dialysis " in Index. 

(b) Reactions having Analytical Interest (Tests'). 

(The iron occurring as a ferrous salt.) 

First Analytical Reaction. — Pass sulphuretted hydrogen (H 2 S) 
through a solution of a ferrous salt (c. //., ferrous sulphate) 
slightly acidulated by hydrochloric acid ; no precipitate occurs. 

This is a valuable negative fact, as will be evident presently. 

Second Analytical Reaction, — Add sulphydrate of ammo- 
nium (NHJ-IS) to solution of a ferrous salt; a black precipi- 
tate of ferrous sulphide (FeS) falls. 



158 THE METALLIC RADICALS. 

FeS0 4 + 2NH 4 HS = FeS + (NH 4 ) 2 SO, + H 2 S. 

Third Analytical Reaction. — Add solution of ferroeyanide of 
potassium (yellow prussiate of potash), K 4 Fe"Cy 6 , or K 4 Fcy"", 
to solution of a ferrous salt ; a precipitate (K 2 Fe"Fe // Cy 6 , or 
K 2 Fe"Fcy) falls, at first white or bluish-gray, but rapidly be- 
coming blue, owing to absorption of oxygen. 

Fourth Analytical Reaction. — To solution of a ferrous salt 
add ferricyanide of potassium (red prussiate of potash), 
K 6 Fe'". 2 Cy 12 , or K 6 Fdcy ; a precipitate (Fe" 3 Fe'" 2 Cy 12 , or 
Fe" 3 Fdcy) (Turnbull's blue) resembling Prussian blue in 
color is thrown down. 

Other Analytical Reactions. — The precipitates produced from 
ferrous solutions on the addition of alkaline carbonates, phos- 
phates, and arseniates, as already described in the synthetical 
reactions of ferrous salts, are characteristic, and hence have a 
certain amount of analytical interest, but are inferior in this 
respect to the four reactions above mentioned. 

Note. — Alkalies (potash, soda, or ammonia) are incomplete 
precipitants of ferrous salts, hence are almost useless as tests, 
To solution of a ferrous salt add ammonia (NH 4 HO) ; on fil- 
tering off the whitish ferrous hydrate and testing the solution 
with sulphydrate of ammonium, iron will still be found. To 
another portion of the ferrous solution add a few drops of nitric 
acid or excess of chlorine-water, and boil ; this converts the 
ferrous into ferric salt, and now alkalies will wholly remove 
the iron, as already twice seen during the performance of the 
synthetical experiments. 

In actual analysis, the separation of iron as ferric hydrate is an 
operation of frequent performance. This is always accomplished by 
the addition of alkali, and, if the iron occurs as a ferrous salt, by 
previous ebullition with a little nitric acid. Ferroeyanide and ferrid- 
cyanide of potassium are the reagents used in distinguishing ferrous 
from ferric salts. 

(The iron occurring as a ferric salt.) 

Fifth Analytical Reaction. — Through a ferric solution (fer- 
ric chloride, e.g.) pass sulphuretted hydrogen ; a white precipi- 
tate of the sulphur of the sulphuretted hydrogen falls, and the 
ferric is reduced to a ferrous salt, the latter remaining in solu- 
tion. This reaction is of frequent occurrence in practical 



2Fe 2 Cl 6 + 2H 2 S = 4FeCl 2 + 4HC1 + S,. 
Sixth Analytical Reaction. — Add sulphydrate of ammo- 
nium to a ferric solution ; the latter is reduced to the ferrous 
state, and black ferrous sulphide (FeS) is precipitated as in 
the second analytical reaction, sulphur being set free. 



ZINC, ALUMINIUM, IRON. 159 

Seventh Analytical Reaction. — To a ferric solution add ferro- 
cyanide of potassium (K 4 FeCy 6 , or K 4 Fcy"") ; a precipitate 
of Prussian blue, the common pigment, occurs (Fe'" 4 3Fe"Cy 6 , 
or Fe'" 4 Fcy"" 3 ). 

Eighth Analytical Reaction. — To a ferric solution add solu- 
tion of ferridcyanide of potassium ; no precipitate occurs, but 
the liquid is darkened to a brownish-red or to a greenish or 
olive hue if the salts are not quite pure. 

Ninth Analytical Reaction. — This is the production of a red 
precipitate of ferric hydrate, on the addition of alkalies to fer- 
ric salts, and is identical with the twelfth synthetical reaction. 

Note. — This reaction illustrates the conventional character of the 
terms synthesis and analysis. It is of equal importance to the 
manufacturer and the analyst, and is synthetical or analytical ac- 
cording to the intention with which it is performed. 

Other ferric reactions have occasional analytical interest. In 
neutral ferric solutions the tannic acid in aqueous infusion of 
galls occasions a bluish-black inky precipitate, the basis of most 

black writing inks. SuJphocyanide of Potassium (KCyS) 

causes the formation of ferric sulphocyanide, which is of a 

deep blood-red color. There is no ferric carbonate ; alkaline 

carbonates cause the precipitation of ferric hydrate, while car- 
bonic acid gas escapes. 

Note. — Cyanogen (CN, or Cy'), ferrocyanogen (FeC 6 N 6 , or FeCy G , 
or simply Fcy //V/ ), and ferricyanogen (Fe 2 Cy 12 , or Fdcy VI ), are radi- 
cals which play the part of non-metallic elements, just as ammonium 
in its chemical relations resembles the metallic elements. They will 
be again referred to. 

Memorandum. — The reader must on no account omit to write 
out equations or diagrams expressive of each of the reactions 
of iron, analytical as well as synthetical. It is presumed that 
this has already been done immediately after each reaction has 
been performed. 

directions for applying the foregoing analytical 
reactions to the analysis of an aqueous solution 
of salts containing one of the metals, zlnc, 
Aluminium, Iron. 
Add solution of ammonia gradually : 

A dirty-green precipitate indicates iron in the state of a 
ferrous salt. 

A red precipitate indicates iron in the state of a ferric salt. 
A white precipitate, insoluble in excess, indicates the pres- 
ence of an aluminium salt. 



160 THE METALLIC RADICALS. 

A white precipitate, soluble in excess, indicates zinc. 

These results may be confirmed by the application of some of the 
other tests to fresh portions of the solution. 

TABLE OF SHORT DIRECTIONS FOR APPLYING THE FOREGOING 
ANALYTICAL REACTION TO THE ANALYSIS OF AN AQUEOUS 
SOLUTION OF SALTS OF ONE, TWO, OK ALL THREE OF 
THE METALS, ZlNC, ALUMINIUM, IRON. 

Boil about half a test-tubeful of the solution with a few drops of 
nitric acid. This insures the conversion of ferrous into ferric salts, 
and enables the next reagent (ammonia) completely to precipitate 
the iron. Add excess of ammonia, and shake the mixture. Filter. 



Precipitate 

Al Fe* 

Dissolve in HC1, add excess of KIIO, 

stir, filter. 



Ppt. 

Fe 

(red ppt.). 



Filtrate 

Al. 

Make slightly acid by HC1, 

and add excess of NH 4 HOf 

(white ppt.). 



Filtrate 

Zn. 

Test by NHJIS 

(white ppt.). 



Note I. — If iron is present, portions of the original solution 
must be tested by ferridcyanide of potassium for ferrous, and 
by ferrocyanide for ferric salts ; dark-blue precipitates with 
both indicate both salts. 

Note II. — If no ferrous salt is present, ebullition with nitric 
acid is unnecessary. It is, perhaps, therefore advisable always 
to determine this point by previously testing a little of the 
original solution with ferridcyanide ; if no blue precipitate 
occurs, the nitric acid treatment may be omitted. 

* The aluminium precipitate (Al 2 6HO) is white, the iron (Fe 2 6HO) 
red. If the precipitate is red, iron must be and aluminium may be 
present ; if white, iron is absent, and further operations on the ppt. 
are unnecessary. This precipitate (Al 2 6HO and Fe 2 6HO) may also, 
if sufficient is at disposal, be analyzed by simply well shaking a 
washed portion in a tube with solution of potash or soda ; the hydrate 
of iron is not thereby affected, while the hydrate of aluminium is dis- 
solved, and may be detected in the clear decanted fluid by neutralizing 
all alkali by a little excess of acid, and then adding excess of ammonia. 

f Alumina, when in small quantity, is sometimes prevented from 
being precipitated by ammonia through the presence of organic mat- 
ter derived from the filter-paper by action of the potash. In cases of 
doubt, therefore, before adding ammonia boil the liquid with a little 
nitric add, which destroys any organic matter. Avoid great excess of 
ammonia. 



CHART FOR METALS HITHERTO CONSIDERED. 161 





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162 THE METALLIC RADICALS. 

Chart for all Metals hitherto considered. 

The preceding Table (vide p. 161) is perhaps the best, but not the 
only, adaptation of the ordinary reactions to systematic analysis. In 
it the analytical scheme for the third group is added to that of the 
first two groups. As before, analysis is commenced by the addition 
of chloride of ammonium (NH 4 C1) to prevent partial precipitation 
of magnesium, and by ammonia (NH 4 HO) to neutralize any acid. 
For acid destroys the group precipitant, sulphydrate of ammonium 
(NHJECS), preventing its useful action, and causing a precipitation 
of the free sulphur it commonly contains. Any precipitate by the 
ammonia may be disregarded, for the sulphydrate attacks both solid 
and liquid. 

Note. — When a test gives no reaction, absence of the body sought 
for may be fairly inferred. If a group-test (that is, a test which 
precipitates a group of substances) gives no reaction, the analyst 
is saved the trouble of looking for any of the members of that 
group. 

QUESTIONS AND EXERCISES. 

207. Name the chief ores of iron. 

208. How is the metal obtained from the ores ? 

209. What is the chemical difference between cast iron, wrought 
iron, and steel? 

210. Explain the process of welding. 

211. What is the nature of chalybeate waters? 

212. Illustrate by formula the difference between ferrous and ferric 
salts. 

213. Under what different circumstances may the atom of iron be 
considered to exert bivalent, trivalent, and sexivalent activity ? 

214. Write a paragraph on the nomenclature of iron salts. 

215. Give a diagram of the official process for the preparation of 
ferrous sulphate. 

216. In what respects do Sulphate of Iron, Granulated Sulphate 
of Iron, and dried Sulphate of Iron differ? 

217. How is ferrous sulphate obtained on the large scale? 

218. Give the chemical names of white, green, and blue vitriol. 

219. Why does ferrous sulphate become brown by prolonged 
exposure to air? 

220. Show the formation of Ferrous Carbonate by a diagram. 

221. Describe the action of atmospheric oxygen on ferrous carbo- 
nate. Can the effect be prevented ? 

222. In what order would you mix the ingredients of Mistura 
Fcrri Composite ', and why ? 

223. Write out an equation illustrative of the formation of the 
Phosphate of Iron. 

224. Why is bicarbonate of sodium used in the preparation of 
ferrous phosphate? 

225. Which four compounds of iron may be formed by the direct 
union of their elements ? 



ARSENICUM. 103 

226. Give the official method for the preparation of Solution of 
Ferric Chloride. 

227. Of what use is the spirit in Tincture of Perchloride of Iron ? 

228. How may Ferrous be converted into Ferric Sulphate? 

229. What is the formula of Ferric Acetate ? And how is it pre- 
pared for use in pharmacy? 

230. Give the formula for Ftrri Peroxidum Hydration, B. P. 

231. How does Ferric Hydrate act as an antidote to arsenic? 

232. What are the properties of anhydrous ferric oxide ? 

233. What are the general characters and mode of production of 
the medicinal scale preparations of iron ? 

234. In what state is the iron in Vinum Ferri Amarum, U. S. P. ? 

235. What other form of Wine of Iron is official? 

236. Give equations illustrating the chief steps in the artificial 
production of the so-called Magnetic Oxide of Iron. 

237. How is precipitated magnetic oxide of iron distinguished 
from the varieties made directly from the metal? 

238. Why is magnetic oxide of iron directed to be dried at a tem- 
perature not exceeding 120° Fahr. ? 

239. Give a diagram showing the formation of Ferric Nitrate. 

240. AVork out a sum showing how much ferric oxide will yield, 
theoretically, one hundred-weight of iron. Ans. 160 lbs. 

241 . What are the properties of anhydrous ferric oxide ? 

242. Explain the action of the following tests for iron, distin- 
guishing between ferrous and ferric reactions, and illustrating each 
by an equation or a diagram : — a. Sulphydrate of ammonium ; 
b. Ferrocyanide of potassium ; c. Ferridcyanide of potassium ; 
d. Caustic alkalies ; e. Sulphocyanide of potassium. 

243. Describe the action of ammonia on salts of iron, aluminium, 
and zinc respectively. 

244. What precautions must be used in testing for calcium a solu- 
tion containing iron? 

245. How is magnesium detected in the presence of zinc ? 

246. How is aluminium detected in the presence of magnesium ? 

247. Draw up a scheme for the analysis of an aqueous liquid con- 
taining salts of iron, barium, and potassium. 

248. How may zinc, magnesium, and ammonium be consecutively 
removed from aqueous solution ? 



ARSENICUM AND STIBIUM OR ANTIMONY. 

These elements resemble metals in appearance and in the character 
of some of their compounds ; but they are still more closely allied to 
the non-metals, especially to phosphorus and nitrogen. Their atoms 
are quinquivalent (As v , Sb v ), as seen in arsenic anhydride (As./),) 
and pentachloridc of antimony (SbCl 5 ), but usually exert trivalent 
activity only (As IU , Sb 111 ), as seen in the hydrogen and other coin- 
pounds (AsH 3 , AsCl 3 , AsBr s , Asl 3 ). A few preparations of these 
elements are used in medicine; but all are more or less powerful 
poisons, and hence have considerable toxicological interest. The 



164 THE METALLIC RADICALS. 

iodide (Arsenii Iodidum, U. S. P.) may be made by cautiously fusing 
together atomic proportions of arsenicum and iodine. It is an 
orange-red crystalline solid, soluble in water. The Liquor Arsenii 
et Hydrargyrilodidi, U. S. P.. or ''Donovan's Solution," is made by 
dissolving iodide of arsenicum and red iodide of mercury in water, 
in the proportion of 1 per cent, of each. The old Donovan's Solu- 
tion contained in each fluidounce (wine measure) the equivalents of 
1 grain of white arsenic (As 2 3 ), 2 grains of peroxide of mercury, 
and about 7 grains of iodine. 

Arsenicum is an exception to the rule that the atomic weights 
(taken in grains, grammes, or other weight) of elements, under sim- 
ilar circumstances of temperature and pressure, give equal volumes 
of vapor, the equivalent weight (75) of arsenicum only occupying 
half such a volume. Hence, while the molecular weights (that is. 
double the atomic weights of oxygen (0 2 = 32), hydrogen (Ff 2 = 2), 
nitrogen (N 2 = 28), etc.) give a similar bulk of vapor at any given 
temperature and pressure, the double atomic weight of arsenicum 
(As 2 =150). at the same temperature and pressure, only affords half 
this bulk. It would appear, therefore, that the molecule of arsenicum 
contains four atoms, and that its formula is As 4 . As in the case of 
sulphur, however, arsenicum, in the state ordinarily known to us, 
may be abnormal, and conditions yet be found in which the molecular 
weight is double (instead of quadruple) the atomic weight. 

From observed analogy between the two metals, the molecular 
constitution of stibium is probably similar to that of arsenicum. 



ARSENICUM. 

Symbol As. Atomic weight 74.9. 

Sources. — Arsenical ores are frequently met with in nature, the 
commonest being the arsenio-sulphide of iron (FeSAs). This min- 
eral is roasted in a current of air, the oxygen of which, combining with 
the arsenicum, forms common white arsenic (As 2 3 , possibly As 4 6 ) 
(Acidum Arseniosum. U. S. P.). arsenious oxide, sometimes called 
anhydrous arsenious acid, or, better, arsenious anhydride, which is 
condensed in chambers or long flues. It commonly " occurs as a 
heavy white powder, or in sublimed masses, which usually present a 
stratified appearance, caused by the existence of separate layers, 
differing from each other in degrees of opacity." The vitreous or 
amorphous arsenic is far more soluble than the crystalline variety. 
and in other respects they differ in properties. Such differences 
between the crystalline and amorphous varieties of an element or 
compound are not unfrequent : they have not yet been satisfactorily 
explained. Realgar (red algar) is the red native sulphide (As 2 S 2 ), 
and orpiment (auripigmentum, the golden pigment) the yellow native 
sulphide (As 2 S :i ) of arsenicum. The iodide of arsenicum (As 3 I 3 ) 
(Arsenii Iodidum, U. S. P.) may be made from its elements or by 
dissolving white arsenic in aqueous hydriodic acid and evaporating. 



ARSENICUM. 16' 5 



Reactions having («) Synthetical and (&) Analytical 
Interest. 

(a) Reactions having Synthetical Interest. 
Alkaline Solution of Arsenic. 
First Synthetical Reaction. — Boil a grain or two of powdered 
arsenic (As 2 3 ) in water containing an equal weight of bicar- 
bonate of potassium, and, if necessary, filter. The solution, 
colored with compound tincture of lavender, and containing 1 
per cent, of arsenic, forms the Liquor Pot ass ii Arsenitis ) 
U. S. P. {Fowler s Solution). 

Note. — This official solution does not generally contain arsenite of 
potassium ; for the arsenic does not decompose the carbonate of potas- 
sium, or only after long boiling. From concentrated solutions car- 
bonic acid gas is more quickly eliminated. 

Arsenious Acids and other Arsenites. 

Arsenic or arsenious anhydride (the so-called arsenious acid), 
when dissolved in water, is said to yield true arsenious acid (H 3 As0 3 ) 
■ — the arsenite of hydrogen. 



As 2 3 + 


3H 2 = 


= 2H 3 As0 3 


Arsenious 


Water. 


Arsenious 


anhydride. 




acid. 



When arsenic (As 2 3 ) is dissolved in excess of solutions of potash 
or soda, arsenites are formed having the formulae KH 2 As0 3 and 
NaII 2 As0 3 . Boiled with excess of arsenic, one molecule of these 
salts combines with one of arsenic. The usual character of such 
compounds is that of oily alkaline liquids. Arsenic fused with alka- 
line carbonates yields pyroarscniates (Na 4 As 2 7 or H 4 As 2 7 ) and 
metallic arscnicum. Arsenites have the general formula R/ 3 As0 3 . 

Acid Solution of Arsenic. 

Second Synthetical Reaction. — Boil arsenic with dilute hydro- 
chloric acid. Such a solution made with prescribed propor- 
tions of acid (2 per cent.) and water, and containing 1 per 
cent of arsenic (As 2 ;! ), forms the Liquor Acidi Arseniosi, 
U. S. P. (I)e Valanyuts Solution contained a grain and a 
half per ounce.) 

Note. — No decomposition occurs in this experiment. The liquid 
is simply a- solution of arsenic in dilute hydrochloric acid. These 
two solutions may be preserved for analytical operations. 

Metn. — The practical student should boil arsenic in water also. 
and thus have an acid, alkaline, and aqueous solution for analytical 
comparison. 



166 THE METALLIC RADICALS. 

Arsenicum. 

Third Synthetical Reaction. — Place a grain or less of arsenic 
at the bottom of a narrow test-tube, cover it with about half 
an inch or an inch of small fragments of dry charcoal, and hold 
the tube, nearly horizontally, in a flame, the mouth being 
loosely covered by the thumb. At first let the bottom of the 
tube project slightly beyond the flame, so that the charcoal 
may become nearly red hot ; then heat the bottom of the tube. 
The arsenic will sublime, become deoxidized by the charcoal, car- 
bonic oxide being formed, and the element arsenium, sometimes 
termed arsenicum, and also formerly called arsenic, be deposited 
in the cooler part of the tube as a dark mirror-like incrustration. 

There is a characteristic odor, resembling garlic, emitted during 
this operation, probably clue to a partially oxidized trace of arseni- 
cum, which escapes from the tube ; for arsenic does not give this 
odor ; moreover, arsenicum being a freely oxidizable element, its 
vaporous particles could scarcely exist in the air in an entirely 
unoxidized state. 

Metallic arsenicum may be obtained in large quantities by the 
above process if the operation be conducted in vessels of commen- 
surate size. But performed with great care, in narrow tubes, using 
not charcoal alone, but black Jinx ( a mixture of charcoal and car- 
bonate of potassium obtained by heating acid tartrate of potassium 
in a test-tube or other closed vessel till no more fumes are evolved), 
the reaction has considerable analytical interest, the garlic odor and 
the formation of the mirror-like ring being highly characteristic of 
arsenicum. Compounds of mercury and antimony, however, give 
sublimates which may be mistaken for arsenicum. 

Arsenic Acid and other Arseniates. 

Fourth Synthetical Reaction. — Boil a grain or two of arsenic 
with a few drops of nitric acid until red fumes cease to. be 
evolved ; evaporate the solution in a small dish to dryness, to 
remove excess of nitric acid ; dissolve the residue in water ; 
the product is Arsen'ic acid (H.. 5 As0 4 ). 

Arsenic acid, when strongly heated, loses the elements of water, 
and arsenic anhydride remains (As 2 5 ). 

Arsenic anhydride readily absorbs water and becomes arsenic acid 
(II 3 AsOJ. Arsenic acid is reduced to arsenious by the action of 
sulphurous acid H 3 As0 4 + H 2 S0 3 = H 3 As0 3 -f H 2 S0 4 . 

Salts analogous to arsenic acid, the arseniate of hydrogen, are 
termed arseniates, and have the general formula R / g As0 4 . The am- 
monium arseniate (XII 4 )IIAs0 4 may be made by neutralizing arsenic 
acid with ammonia. Its solution in water forms a useful reagent. 

Arsenic acid is used as an oxidizing agent in the manufacture 

of the well-known dye, magenta. 

Arsenite and arseniate of sodium are used in the cleansing opera- 
tions of the calico-printer. 



ARSENICUM. 167 

Pyroarseniate and Arseniate of Sodium. 

Fifth Synthetical Reaction. — Fuse two or three grains of 
common white arsenic (As 2 3 ) with nitrate of sodium (NaN0 3 ) 
and dried carbonate of sodium (Na 2 C0 3 ) in a porcelain cru- 
cible, and dissolve the mass in water ; solution of arseniate of 
sodium (Na 2 HAs0 4 ) results. 



As 2 3 + 2NaN0 3 


+ Na 2 C0 3 


= Na 4 As 2 7 


+ N 2 3 + C0 2 


Arsenic. Nitrate of 


Carbonate 


Pyroarseniate 


Nitrous Carbonic 


sodium. 


of sodium. 


of sodium. 


anbydride. acid gas. 



The official proportions (B. P.) are 10 of arsenic to 8J of nitrate 
of sodium and 5 J of dried carbonate, each powdered, the whole well 
mixed, fused in a crucible at a red heat till effervescence ceases, and 
the liquid poured out on a slab. The product is pyroarseniate of 
sodium (Na 4 As 2 7 ). Dissolved in water, crystallized and dried, the 
salt has the formula Na 2 HAs0 4 ,7H 2 (Sodii Arsenias, U. S. P.). 

Na 4 As 2 7 + 15H 2 = 2(Na 2 HAs0 4 ,7H 2 0). 

Heated to 300° F. the crystals lose all water. A solution of 1 part 
of the anhydrous salt (Na 2 HAs0 4 ) in 99 of water forms the Liquor 
Sodii Arseniatis, U. S. P. The anhydrous salt is used in this 
preparation because the crystallized is of somewhat uncertain 
composition. The fresh crystals are represented by the formula 
Na 2 HAs0 4 ,12H 2 (=53.7 per cent, of water); these soon effloresce 
and yield a stable salt having the formula Na 2 HAs0 4 ,7H 2 (= 40.4 
per cent, of water). To avoid the possible employment of a mix- 
ture of these bodies, the invariable anhydrous salt is officially used, 
constancy In the strength of a powerful preparation being thereby 
secured. 

The student will find useful practice in verifying the above num- 
bers representing the centesimal proportion of water in the two 
arseniates of sodium. This will readily be accomplished if what 
has already been stated respecting a symbol representing a number 
as well as a name, and the remarks concerning a molecular weight, 
be remembered. 

The shape of each of the two varieties of arseniate of sodium 
(Na 2 HAs0 4 ,12H 2 0, and Na 2 HAs0 4 ,7II 2 0) is identical with that 
of the corresponding phosphate of sodium (Na 2 HP0 4 ,12H 2 0, and 
Na 2 IIP0 4 ,7H 2 0) ; the structure of the molecule of the 12-arseniate 
is the same as that of the 12-phosphatc, and the 7-arseniate as that 
of the 7-phosphate ; the two former are isomorphous, the two latter 
are isomorphous. This is only one instance of the strong analogy 
of arsenicum and its compounds with phosphorus and its corre- 
sponding compounds. The preparation and characters of the next 
substance, arseniate of iron, will remind the learner of phosphate 
of iron. 

Arseniate of Iron. Ferrous Arseniate. 
Sixth Synthetical Reaction. — To a hot solution oi' arseniate 
of sodium add a little solution of bicarbonate of sodium, and 



168 THE METALLIC RADICALS. 

then solution of ferrous sulphate ; a precipitate of ferrous ar- 
seniate occurs (Fe 3 2As0 4 ) {Ferri Arsenias, B. P.). On the 
large scale 15f parts of dried arseniate dissolved in 100 of hot 
water, and 20| of sulphate in 120 of hot water, with 4i of bi- 
carbonate of sodium, may be employed. The precipitate should 
be collected on a calico filter, washed, squeezed, and dried at a 
low temperature (100° F.) over a water-bath to avoid excessive 
oxidation. 

2Na 2 HAsO, + 2NaHC0 3 + 3FeS0 4 

Arseniate of Bicarbonate of Ferrous 

sodium. sodium. sulphate. 

= Fe 3 2As0 4 + 3Na 2 S0 4 + 2H,0 + 2C0 2 

Ferrous arseniate. Sulphate of sodium. Water. Carbonic acid gas. 

The use of the bicarbonate of sodium is to ensure the absence of 
free sulphuric acid in solution. Sulphuric acid is a solvent of fer- 
rous arseniate. It is impossible to prevent the separation of sul- 
phuric acid, if only ferrous sulphate and arseniate of sodium be 
employed. At the instant of precipitation ferrous arseniate is white, 
but rapidly becomes of a green or greenish-blue color, owing to ab- 
sorption of oxygen and formation of a ferroso-ferric arseniate. When 
dry it is a tasteless, amorphous, much oxidized powder, soluble in 
acids. 

The Hydride and Sulphides of Arsenicum, and the Ar seniles 
and Arseniates of Copper and of Silver , are mentioned in the 
following analytical paragraphs : — 

(b) Reactions having Analytical Interest ( Tests). 

First Analytical Reaction. — Repeat the third synthetical re- 
action, operating on not more arsenic than has about the bulk 
of a small pin's head, and using not charcoal alone, but the 
black flux already mentioned (p. 166), or a well-made and per- 
fectly dry mixture of charcoal and carbonate of potassium ob- 
tained by heating the bicarbonate of potassium. The tube 
employed should be a narrow test-tube, or, better, a tube 
(easily made from glass tubing) having the following (Ber- 
zelius's) form : — 

Fig. 33. 



The arsenic and black flux are placed in the bulb of the tube, 
which is then heated in a flame ; the arsenicum condenses on 
the constricted portion of the tube. If now the bulb be care- 
fully fused off in a flame, the arsenicum may be chased up and 



ARSENICUM. 169 

down the narrower part of the tube until the air in the tube 
has reoxidized it to arsenious anhydride. 

If the operation has been performed in a less delicate manner 
in an ordinary test-tube, cut or break off portions of the tube 
containing the sublimate of arsenicum, put them into a test- 
tube and heat the bottom of the latter, holding it nearly hori- 
zontally, and partially covering the mouth with the finger or 
thumb ; the arsenicum (As 4 ) will absorb oxygen from the air 
in the tube, and the resulting arsenious anhydride (As. 2 3 ) be 
deposited on the cool part of the tube in brilliant transparent, 
generally imperfect, octahedral crystals. 

Microscopic Test. — Prove that the crystals are identical in 
form with those of common white arsenic, by heating a grain 

Fig. 34. Fig. 34a. 





A sublimate of White Arsenic. (Magnified.) A perfect Octahedron. 

or less of the latter in another test-tube, examining the two 
sublimates by a good lens or compound microscope. 

The appearance of a sublimate of arsenic is peculiar and 
quite characteristic. The primary form of each crystal is an 
octahedron (o-ktw, okto, eight ; kdpa, hedra t side) (fig. 34a), or, 
rarely, a tetrahedron, and in a sublimate a few perfect octa 
hedra are generally present. Usually, however, the crystals 
are modifications of octahedra, such as are shown in fig. 34 — 
which is drawn from actual sublimates. 

Second Analytical Reaction. — Place a thin piece of copper, 
about a quarter inch wide and half inch long, in a solution of 
arsenic, acidified by hydrochloric acid, and boil (nitric acid 
must not be present, or the copper itself will be dissolved) ; 
arsenicum is deposited on the plate in a metallic condition, an 
equivalent portion of copper going into solution. Pour off the 
supernatant liquid from the copper, wash the latter once or 
twice with water, dry the piece of metal by holding in the 
clean lingers and passing through a flame, and finally place it 
15 



170 THE METALLIC RADICALS. 

at the bottom of a clean dry narrow test-tube or a Berzelius 
tube ; sublime as described in the last reaction, again noticing 
the form of the resulting crystals. 

This is commonly known as Reinsch's test of arsenicum, it having 
been introduced by Reinsch in 1843. The tube may be reserved for 
subsequent comparison with an antimonial sublimate (p. 186). 

Note. — Copper itself frequently contains arsenicum, a fact that 
may not, perhaps, much trouble an operator so long as he is per- 
forming experiments in practical chemistry merely for educational 
purposes ; but when he engages in the analysis of bodies of un- 
known composition, he must assure himself that neither his appa- 
ratus nor materials already contain the element for which he is in 
search. 

The detection of arsenicum in metallic copper is best accomplished 
by distilling a mixture of a few grains of the sample with five or six 
times its weight of ferric hydrate or chloride (free from arsenicum) 
and excess of hydrochloric acid. The arsenicum is thus volatilized 
in the form of chloride of arsenicum, and may be condensed in water 
and detected by sulphuretted hydrogen (6th Analytical Reaction) or 
Reinsch's test. The ferric chloride solution is, if necessary, freed 
from any trace of arsenicum hj evaporating once or twice to diTiiess 
with excess of hydrochloric acid. 

Th ird Analytical Reaction : The hydrogen test, or " Marsh 's " 
test. — Generate hydrogen in the usual way from water by zinc 
and sulphuric acid, a bottle of about four or six ounces capacity 
being used, and a funnel-tube and short delivery-tube passing 
through the cork in the usual manner (see following figure). 
Dry the escaping hydrogen (except in rough experiments, 
when it is unnecessary) by adapting to the delivery-tube, by a 
pierced cork, a short piece of wider tubing filled with frag- 
ments of chloride of calcium, a. To the opposite end of the 
drying tube fit a piece of narrow tubing ten or twelve inches 
long, made of hard German glass, and having its aperture nar- 
rowed by drawing out in the flame of the blowpipe. When 
the hydrogen has been escaping for a sufficient number of 
minutes, and at such a rate as to warrant the operator in con- 
cluding that all the air originally existing in the bottle has 
been expelled, set light to the jet, and then pour eight or ten 
drops of the aqueous solution of arsenic, or three or four 
drops of the acid or alkaline solution of arsenic, previously 
prepared, into the funnel-tube, washing the liquid into the 
generating-bottle with a little water. The arsenic is at once 
reduced to the state of arsenicum, and the latter combines 
with some of the hydrogen to form hydride of arsenicum or 
arseniuretted hydrogen gas (AsH 3 ). Immediately hold a piece 
of earthenware or porcelain (the lid of a porcelain crucible, b, 



ARSENICUM. 171 

if at hand) in the hydrogen jet at the extremity of the de- 
livery-tube ; a brown spot of arsenicum is deposited on the 

Fig. 35. 




The Hydrogen Test for Arsenicum. 

porcelain. Collect several of these spots,, and retain them for 
future comparison with antimonial spots (p. 183). 

The separation of arsenicum in the flame is due to the decomposi- 
tion of the arseniuretted hydrogen by the heat of combustion. The 
cool porcelain at once condenses the arsenicum, and thus prevents 
its oxidation to white arsenic, which would otherwise take place at 
the outer edge of the flame. 

Hold a small beaker, c, or wide test-tube over the flame for 
a few minutes ; a white film of arsenic (As 2 3 ) will be slowly 
deposited, and may be further examined in contrast with a 
similar antimonial film (p. 183). 

During these experiments the effect produced by the arsenical 
vapors on the color of the hydrogen-flame will have been noticed ; 
they give it a dull livid tint. This is characteristic. 

Apply the flame of a gas-lamp to the middle of the hard 
delivery -tube, d ; the arseniuretted hydrogen, as before, is de- 
composed by the heat, but the liberated arsenicum (As,) imme- 
diately condenses in the cool part of the tube beyond the flame, 
forming a dark metallic mirror. The tube may be removed ami 
kept for comparison with the antimonial deposit. 

Note I. — Zinc, like copper, frequently itself contains arsenicum. 
When a specimen free from arsenicum is met with, it should be 
reserved for analytical experiments, or a quantity ol' guaranteed 
purity should be purchased of the chemical-apparatus maker. Sul- 
phuric acid is more easily obtained Tree from arsenic. 

Note II. — In delicate and important applications oi' Marsh's test, 
magnesium may be substituted for sine with safety, as arsenicum 



172 THE METALLIC RADICALS. 

has not yet been, and is not likely to be, found in magnesium. 
Magnesium in rods is convenient for this purpose, and may be 
obtained from most dealers in chemicals. Both magnesium and zinc, 
if perfectly pure, react with acids extremely slowly ; the addition of 
a little perchloride of platinum, however, at once promotes an abun- 
dant evolution of hydrogen. 

Note III. — Sulphuric acid, which is often used for drying gases, 
decomposes arseniuretted hydrogen. Chloride of calcium is there- 
fore the appropriate desiccating agent for this gas. 

Note IV. — The original apparatus proposed by Mr. Marsh of Wool- 
wich in 1836 was a U-shaped tube, one limb of which was short and 
closed by a stopcock, so that the whole of a small quantity of the 
arseniuretted hydrogen could be collected and examined at leisure. 

Fourth Analytical Reaction: Fleitmanns test. — Generate 
hydrogen by heating in a test-tube to near the boiling-point a 
strong solution of caustic soda or potash and some pieces of 
zinc (or aluminium). 

(Zn -f 2NaHO = H 2 + Na,ZnO— zincate of sodium.) 

Add a drop of arsenical solution, and spread over the mouth 
of the tube a cap of filter-paper moistened with one drop of 
solution of nitrate of silver. Again heat the tube, taking 
care that the liquid itself shall not spirt up on to the cap. A 
plug of cotton-wool may even be placed in the mouth of the 
test-tube to prevent this spurting. The arsenic is reduced to 
arsenicum. the latter uniting with the hydrogen as in Marsh's 
test ; and the arseniuretted hydrogen, passing up through the 
cap, reacts on the nitrate of silver, causing the production of a 
purplish-black spot. 

AsH 3 + 3H 2 + 6AgN0 3 = H 3 AsO. + 6HX0 3 -f 3Ag 2 . 

Note I. — This reaction is particularly valuable, enabling the ana- 
lyst to quickly distinguish arsenicum in the presence of its sister 
element antimony, which, although it combines with the hydrogen 
evolved from dilute acid and zinc, does not combine with the hydro- 
gen evolved from solution of alkali and zinc, and therefore does not 
give the effect just described. 

Xote II. — Aluminium answers as AvelL as zinc for Fleitmann's test 
(Gatehouse), or magnesium may be used : or, instead of zinc and 
alkali, weak sodium amalgam may be employed (Davy). 

Fifth Analytical Reaction — Bettendorffs Test. — To a solution 
of chloride of tin in strong hydrochloric acid add a very small 
quantity of any arsenical solution. Arsenicum then separates, 
especially on the application of heat, giving the mixture a yel- 
lowish and then brownish hue or grayish-brown turbidity, or 
even a sediment of gray-brown flocks, according to the amount 
present. Much water prevents the reaction ; its presence, there- 



ARSENICUM. 173 

fore, must be avoided as for as possible ; indeed a liquid satu- 
rated by hydrochloric acid gas gives best results. Arsenic in 
sulphuric or hydrochloric acid or in tartar emetic, etc., may be 
detected by this method. Nitrates, such as subnitrate of bis- 
muth, must first be heated with sulphuric acid to remove the 
nitric radical before applying this reduction test for arsenicum. 
The stannous is converted to stannic salt during the reaction. 



Distinction between Arsenious and Arsenic Combinations. — The 
above tests are those of arsenicum, whether existing in the arsen- 
ious or arsenic condition, though from the latter the element is not 
generally eliminated so quickly as from the former. Of the fol- 
lowing reactions, that with nitrate of silver at once distinguishes 
arsenious acid and other arsenites from arsenic acid and other 
arseniates. 

Mem. — The exact nature of all these analytical reactions will be 
more fully evident if traced out by diagrams or equations. 



Sixth Analytical Reaction. — Through an acidified solution 
of arsenic pass sulphuretted hydrogen ; a yellow precipitate of 
sulphide of arsenicum or arsenious sulphide (As 2 S 3 ) quickly 
falls. Add an alkaline hydrate or sulphydrate to a portion of 
the precipitate ; it readily dissolves. The precipitate conse- 
quently would not be obtained on passing sulphuretted hydro- 
gen through an alkaline solution of arsenic. To another por- 
tion of the precipitate, well drained, add strong hydrochloric 
acid; it is insoluble, unlike sulphide of antimony. Neither 
sulphide is soluble in the weak acid. 

Note I. — Cadmium also affords a yellow sulphide in an acid solu- 
tion by action of sulphuretted hydrogen, but this sulphide is insol- 
uble in alkaline liquids. Under certain circumstances, tin, too, 
yields a yellow sulphide ; but tin is otherwise easily distinguished 
(vide Tin). 

Note II. — A trace of sulphide of arsenicum is sometimes met with 
in sulphur (distilled from arsenical pyrites). It may be detected by 
digesting the sulphur in solution of ammonia, filtering, and evapo- 
rating to dryness ; a yellow residue of sulphide of arsenicum is 
obtained if that substance be present. 

Seventh Analytical Reaction. — Through an acidified solution 
of arsenic acid, or any other arseniate, pass a rapid current of 
sulphuretted hydrogen ; arsenic sulphide (As a S 6 ) slowly falls. 
Brauner and Tornieck state that by a slow current the arsenic 
compound is gradually reduced to the arsenious and a yellow- 
precipitate of arsenious sulphide and sulphur (As,S :t -f- S,.) 
15* 



174 THE METALLIC RADICALS. 

slowly falls. The precipitate is soluble in alkaline hydrates 
and sulphydrates. This reaction is more rapid if the solution 
be warmed. 

Chemical Analogy of Sulphur and Oxygen. — The potassium arsenite 
and sulph-arsenite, arseniate and sulph-arseniate, have the composi- 
tion represented by the following formulae : — 

K 3 As0 3 K 3 As0 4 

K 3 AsS 3 K 3 AsS 4 ; 

and the corresponding ammonium and sodium salts have a similar 
composition : — 

6NH 4 HS -f As 2 S 3 = 2(NH 4 ) 3 AsS 3 + 3H 2 S 
6XHJIS + As 2 S 5 = 2(NH 4 ) 3 AsS 4 + 3H 2 S. 

Eighth Analytical Reaction. — To an aqueous solution of 
arsenic add two or three drops of solution of sulphate of cop- 
per, and then cautiously add diluted solution of ammonia, drop 
by drop, until a green precipitate is obtained. The production 
of this precipitate is characteristic of arsenicum. To a por- 
tion of the mixture add an acid ; the precipitate dissolves. To 
another portion add alkali : the precipitate dissolves. These 
two experiments show the advantage of testing a suspected 
arsenical solution by litmus-paper before applying this reaction ; 
if acid, cautiously adding alkali, if alkaline, adding acid, till 
neutrality is obtained. (Or a special copper reagent may be 
used; see a note to the Eleventh Analytical Reaction, below). 

The precipitate is arsenite of copper (Cu^HAsOg) or Scheelrfs 
Green. More or less pure, or mixed with acetate or, occasionally, 
carbonate of copper, it is used as a pigment under many names, such 
as Brunswick Green and Schweinfurth Green, by painters and others. 

Ninth Analytical Reaction. — Apply the test just described 
to a solution of arsenic acid or other arseniate ; a somewhat 
similar precipitate of arseniate of copper is obtained. 

Tenth Analytical Reaction. — Repeat the eighth reaction, 
substituting nitrate of silver for sulphate of copper; in this 
case yellow arsenite of silver (Ag 3 As0 3 ) falls, also soluble in 
acids and alkalies. 

Eleventh Analytical Reaction. — Apply the test to a solution 
of arsenic acid or other arseniate ; a chocolate-colored precipi- 
tate of arseniate of silver (Ag 3 As0 4 ) falls. 

This reaction may be utilized for the detection of arsenic when 
occurring in ores and other substances as ordered by the U. S. Phar- 
macopoeia in the case of Ardimonii Sulphidum Purificatum; 

" If 2 gm. of the salt be mixed and cautiously ignited, in a por- 
celain crucible, with 8 gm. of pure nitrate of sodium, and the fused 



AKSENICTJM. 175 

mass boiled with 25 gm. of water, there will remain a residue which 
should be white, or nearly so, and not yellowish nor brownish (abs. 
of other metallic sulphides). On boiling the filtrate with an excess 
of nitric acid, until no more nitrous vapors are evolved, then dis- 
solving in it 0.1 gm. of nitrate of silver, filtering again, if neces- 
sary, and cautiously pouring a few drops of water of ammonia on 
top, not more than a white cloud, but no red nor reddish precipitate, 
should appear at the line of contact of the two liquids (abs. of more 
than traces of arsenic)." 

Copper and Silver Reagents for Arsenicuih. — The last four reac- 
tions may be performed with increased delicacy and certainty of 
result if the copper and cilver reagents be previously prepared in 
the following manner : To solution of pure sulphate of copper (about 
1 part in 20 of water) add ammonia until the blue precipitate at first 
formed is nearly but not quite redissolved ; filter and preserve the 
liquid as an arsenicum reagent, labelling it solution of ammonio-sul- 
phate of copper (B. P.). Treat solution of nitrate of silver (about 
1 part in 40) in the same way, and label it solution of ammonio- 
nitrate of silver (B. P.). The composition of these two salts will be 
referred to subsequently. 

Arsenious and Arsenic Compounds. — While many reagents may 
be used for the detection of arsenicum, only nitrate of silver, as 
already stated, will readily indicate in which state of oxidation the 
arsenicum exists ; for the two sulphides and the two copper precip- 
itates, though differing in composition, resemble each other in ap- 
pearance, whereas the two silver precipitates differ in color as well 
as in composition. 

Soluble arseniates also give insoluble arseniates with solutions of 
salts of barium, calcium, zinc, and some other metals. 

In group-testing, arsenicum, if existing as arsenic acid or other 
arseniate, is not readily affected by such tests as sulphuretted hydro- 
gen or even hydrogen itself. Hence, if its presence in that state is 
suspected, the liquid under analysis should be warmed with a little 
sulphurous acid or oxalic acid, and then tested with sulphuretted 
hydrogen. 

Antidote. — In cases of poisoning by arsenic or arsenical prep- 
arations, the most effective antidote is recently precipitated 
moist ferric hydrate (Ferri Oxidum IL/drafum, U. 8. P.). It 
is perhaps best administered in the form of a mixture or so- 
lution of ferric sulphate (Liquor Ferri Tersulphatis, V. S. P.) 
or perchloride of iron (Liquor or Tinctura) with carbonate of 
sodium — two or three ounces of the former to about one ounce 
of the crystals of the latter. Instead of the carbonate oi' so- 
dium, about a quarter of an ounce of calcined magnesia may 
be used. (See Fcrri Oxidum Hydratum cum Magnesia^ l. S. 
P., page 149.) These quantities will render at least 10 grains 
of arsenic insoluble. Kinetics should also be given, and the 
stomach-pump applied as quickly as possible. 



176 THE METALLIC RADICALS. 

The above statements regarding the antidote for arsenic may be 
verified by mixing the various substances together, filtering, and 
proving the absence of arsenicum in the filtrate by applying some 
of the foregoing tests. 

Mode of Action of the Antidote. — The action of the carbonate of 
sodium or the magnesia is to precipitate ferric hydrate (Fe 2 6HO) — 
chloride of sodium (NaCI) or magnesium (MgCi 2 ) being formed, 
which are harmless, if not beneficial, under the circumstances. 
The reaction between the ferric hydrate and the arsenic results in 
the formation of insoluble ferrous arseniate. 

2(Fe,6HO) + As 2 3 = Fe 3 2As0 4 + 5H 2 + Fe2HO 

Ferric Arsenic. Ferrous Water. Ferrous 

hydrate. arseiriate. hydrate. 

The so-called Solution of Dialyzed Iron (see Index) is also, as 
might be expected from its composition, an antidote to arsenic. It 
should be administered with a little bicarbonate of either sodium or 
potassium, or with magnesia, or with any other salt which serves to 
neutralize any acid that may be present. 



QUESTIONS AND EXERCISES. 

249. What is the formula of a molecule of arsenicum? 

250. In what form does arsenicum occur in nature ? 

25 1 . Describe the characters of white arsenic. 

252. Name the official preparations of arsenicum. 

253. What proportion of arsenic (As 2 3 ) is contained in Liquor 
Potassii Arsenitis, U. S. P., and in Liquor Acidi Arseniosi, U. S. P.? 

254. By what method may arsenic be reduced to arsenicum ? 

255. Give the formulae of arsenious and arsenic acids and anhy- 
drides. 

256. Explain, by diagrams, the reactions which occur in convert- 
ing arsenic into Arseniate of Sodium by the process of the British 
Pharmacopoeia. 

257. Why is anhydrous instead of crystallized arseniate of sodium 
employed in the preparation of Liquor Sodii Arseniatis, U. S. P.? 

258. In the preparation of Arseniate of Iron from ferrous sulphate 
and arseniate of sodium, why is acetate of sodium included ? 

259. Describe the manipulations necessary to obtain arsenic in its 
characteristic crystalline form. 

260. How is Reinseh's test for arsenicum applied, and under what 
circumstances may its indications be fallacious ? 

261. Give the details of Marsh's test for arsenicum, and the pre- 
cautions to be observed in its performance. Explain the reactions 
by diagrams ? 

262. What peculiar value has Fleitmann's test for arsenicum? 

263. Describe the conditions under which sulphuretted hydrogen 
becomes a trustworthy test for arsenicum ? 



ANTIMONY. 177 

264. How may a trace of sulphide of arsenicum be detected hi 
sulphur ? 

265. How are the salts of copper and silver applied as reagents 
for the detection of arsenicum ? 

266. How are arsenites distinguished from arseniates ? 

267. Mention the best antidote in cases of poisoning by arsenic, 
explain the process by which it may be most quickly prepared, and 
describe its action. 

268. Do you know of any other antidote to arsenic ? If so, de^ 
scribe the mode of administration. 



ANTIMONY. 

Symbol Sb (Stibium). Atomic weight 120. 

Sources and Uses. — Antimony occurs in nature chiefly as sulphide, 
Sb 2 S 3 . The crude or black antimony of pharmacy is this native sul- 
phide freed from impurities by fusion ; it has a striated, crystalline, 
lustrous fracture ; subsequently powdered, and if it contains any 
soluble salt of arsenicum, the latter removed by digestion in solution 
of ammonia, it forms the grayish-black, crystalline Antimonii >SuI- 
phidum, U. S. P. When this powder is washed with solution of 
ammonia to remove any traces of sulphide of arsenicum and dried, 
it forms the Antimonii Sulphidum Purijicatum, U. S. P. The metal 
is obtained from the sulphide by roasting, the resulting oxide being 
reduced with charcoal and carbonate of sodium. Metallic antimony 
is an important constituent of Type-metal, Britannia metal (tea and 
coffee pots, spoons, etc.), and the best varieties of Pewter. The old 
pocula emetica, or everlasting emetic cups, were made of antimony ; 
wine kept in them for a day or two was said to have acquired a vari- 
able amount of emetic quality. The metal is not used in making 
official antimonial preparations, the sulphide alone being, directly 
or indirectly, employed for this purpose. 

Antimony has very close chemical analogies with arsenicum. Its 
atom, in the common salts, exerts trivalent activity (e.g., SbCl 3 ), but 
sometimes it is quinquivalent (e. g., SbCl 5 ). 

Antimony, like arsenicum, unites with iodine to form a tri-iodide 
(Sbl 3 ). A bromide (SbBr 3 ) is also known. 

Reactions having (a.) Synthetical and (/>) Analytical 
Interest. 

(«) Reactions having Synthetical Interest. 
Chloride of Antimony. Antimonious Chloride. 
First Synthetical Reaction. — Boil half an ounce or less of 
sulphide of antimony with four or five times its weight of 
hydrochloric acid in a dish in a fume-chamber or in the open 
air; sulphuretted hydrogen is evolved, and solution of chloride 
of antimony, SbCl ;1 , is obtained. 



178 THE METALLIC RADICALS. 

Sb 2 S 3 + 6HC1 = 2SbCl 3 + 3H 2 S 

Sulphide of Hydrochloric Chloride of Sulphuretted 

antimony, acid. antimony. hydrogen. 

This solution, cleared by subsidence, is what is commonly known 
as Butter of antimony {Liquor Antimonii Chloridi, B. P.). If pure 
sulphide has been used in its preparation, the liquid is nearly color- 
less ; but much of that met with in veterinary pharmacy is simply 
a by-product in the generation of sulphuretted hydrogen from native 
ferruginous sulphide of antimony and hydrochloric acid, and is more 
or less brown from the presence of chloride of iron. It not unfre- 
quently darkens in color on keeping ; this is due to absorption of 
oxygen from the air and conversion of light-colored ferrous into 
dark-brown ferric chloride or oxychloride. 

True butter of antimony (SbCl 3 ) is obtained on evaporating the 
above solution to a low bulk, and distilling the residue. The butter 
condenses (as a white crystalline semi-transparent mass in the neck 
of the retort) ; at the close of the operation it may be easily melted 
and run down in a bottle, which should be subsequently well stop- 
pered. 

Pentachloride of antimony (SbCl 5 ), or antimonic chloride, is a 
fuming liquid, obtained on passing chlorine over the lower chloride. 

Oxychloride of Antimony. Antimonious Oxychloride. 

Second Synthetical Reaction. — Pour the solution of chloride 
of antimony produced in the last reaction into several ounces 
of water ; a white precipitate of oxychloride of antimony 
(2SbCl 3 ,5Sb 2 3 ) falls, some chloride of antimony remaining in 
the supernatant acid liquid. 

This is the old pulvis Algarothi, pulvis angelicus, or mereurius 
vita;. On standing under water it gradually becomes crystalline. 



12SbCl 3 + 


15H 2 = 


= 2SbCl 3 ,5Sb 2 8 


-f 30HC1 


Chloride of 


Water. 


Oxychloride of 


Hydrochloric 


antimony. 




antimony. 


acid. 



Oxide of Antimony. Antimonious Oxide. 
Well wash the precipitate with water, by decantation (vide 
p. 109), and add solution of carbonate of sodium ; the chloride 
remaining with the oxide is thus decomposed, and oxide of 
antimony (Sb 2 3 ) alone remains. This is Antimonii Oxidum, 
U. S. P. It is of a light buff or grayish-white color, or quite 
white if absolutely free from iron, insoluble in water, soluble 
in hydrochloric acid, fusible at a low red heat. The moist 
oxide of antimony may be well washed and employed for the 
next reaction, or dried over a water-bath. At temperatures 
above 212° oxygen is absorbed, and other oxides of antimony 
formed. The presence of the latter is detected on boiling the 
powder in solution of acid tartrate of potassium, in which 



ANTIMONY. 179 

oxide of antimony (Sb 2 3 ) is soluble, but antimonic anhydride 
(Sb 2 5 ) and the double oxide or so-called antimonious anhydride 
(Sb 4 8 ) are insoluble. 



2SbCl s ,5Sb 2 3 + 3Na 2 CO s = 


= 6Sb 2 3 + 6NaCl + 3CO, 


Oxychloride of Carbonate of 


Oxide of Chloride of Carbonic 


antimony. sodium. 


antimony. sodium. acid gas. 



The higher oxide of antimony (Sb 2 5 ), termed antimonic oxide 
or anhydride, corresponding with arsenic anhydride, is obtained on 
decomposing the pentachloride by water, or on boiling metallic anti- 
mony with nitric acid. The variety obtained from the chloride differs 
in saturating power from that obtained from the metal, and is termed 
metantimonic (juera, meta, beyond). 

Tartar Emetic. 

Third Synthetical Reaction. — Mix the moist oxide of anti- 
mony obtained in the previous reaction with about an equal 
quantity of cream of tartar (6 of the latter to 5 of the dry 
oxide) and sufficient water to form a paste ; set aside for a day 
to facilitate complete combination ; boil the product with water, 
and filter; the resulting liquid contains the oxy-tartrate of anti- 
mony and potassium (KSbOC 4 H 4 6 ), potassio-tartrate of anti- 
mony, tartrated antimony, or tartar emetic (emetic, from epiat, 
emeo, I vomit ; tartar, from rdprapos, tartaros See Index). 

2KHC 4 H 4 6 + Sb a O s = 2KSbOC 4 H 4 6 + H 2 

-Acid tartrate of Oxide of Tartar emetic. Water, 

potassium. antimony. 

On evaporation the salt is obtained in colorless transparent 
triangular-faced crystals of the above composition, with a mole- 
cule of water of crystallization, forming the Antimonii ct Po- 
tassii Tartras, U. S. P., 2KSbOC 4 H 4 6 ,H 2 0. 

The formula for tartar emetic is apparently inconsistent with 
the general formula for tartrates (R'R'C 4 H 4 6 ) ; this will be 
subsequently fully explained in connection with Tartaric Acid. 
The salt appears to be an oxy tartrate (KSbC 4 H 4 (J 0). 

Tartar emetic is soluble in water, and slightly so in proof- 
spirit. Dissolved in sherry wine, it forms the official Ymum 
Antimonii, U. S. P. 

Sulphurated Antimony and Various Oxysulphides of 
Antimony. 

Fourth Synthetical Reaction. — Boil a few grains of sulphide 
of antimony and of sulphur with solution of soda in a test-tube, 
and filter (or larger quantities in larger vessels, 1 part oi 1 sul- 
phide to 12 of soda, and 30 of water for 2 hours, frequently 
stirring, and occasionally replacing water lost by evaporation). 



180 THE METALLIC RADICALS. 

Into the filtrate, before cool, stir diluted sulphuric acid until 
the liquid is slightly acid to test-paper ; a brownish-red precip- 
itate of oxysulphide of antimony, Antimonium Sulphuratum, 
U. S. P., falls ; filter, wash, and dry over a water-bath. It is a 
mixture of the so-called pentasulphide of antimony (Sb 2 S 5 or 
Sb 2 S 3 S 2 ") with a little oxide (Sb 2 3 or possibly Sb 3 S 5 ). The 
oxide results from the double decomposition of sulphide of 
antimony and soda. 

These are some of the many varieties of mineral kermes, so called 
from their similarity in color to the insect kermes. Kermes is the 
name, now obsolete, of the Coccus I litis, a sort of cochineal, insect, 
full of reddish juice, and used for dyeing from the earliest times. 
The term mineral kermes was apparently applied originally to the 
amorphous or precipitated orange sulphide of antimony (SbS 3 ). It 
afterward included any oxysulphide and pentasulphide. A brownish- 
red variety may be prepared without the addition of any free sul- 
phur. The color of the precipitate is affected by the temperature as 
well as state of dilution of the alkaline liquid when the acid is added. 
When the alkaline liquid is boiled, especially if long exposed to 
air, oxygen is absorbed by some of the antimony, whose sulphur, 
uniting with the trisulphate, forms a portion of the lighter yellow 
pentasulphide. 

Explanation of Processes. — The sulphides and oxides of antimony, 
like those of arsenicum, react with the sulphides, hydrates, and 
oxides of certain metals to form salts of greater or less degree of 
solubility. Thus, antimonite of sodium (Na 3 Sb0 3 ) is formed and 
remains in solution, and sulph-antimoniate of sodium (Na 3 SbS 3 ) is 
formed and is deposited in brilliant yellow tetrahedral crystals when 
a hot alkaline solution of the trisulphide of antimony is set aside to 
cool. Sulphur, being present, is slightly soluble in antimoniate of 
sodium (Na 3 Sb0 4 ), and sulph-antimoniate of sodium (Na 3 SbS 4 ) is 
produced. 



2Sb 2 S, + 

Sulphide of 
antimony. 


6NaIIO = 

Soda. Si 


2Na 3 SbS 3 + SbjOs + 3H 2 

llph-antimonite Antimonious Water, 
of sodium. oxide. 




SbA + 6XaIIO 

Antinionious Soda, 
oxide. 


= 


2Na 3 Sb0 3 + 

Antimonite 
of sodium. 


3H 2 

Water. 






2Sb,S 3 + 

Sulphide of 
antimony. 


2S 2 


+ 


6NaIIO 

Soda. 






= 2Na 3 SbS 4 + Sb 2 5 + 

Sulph-antimoniate Antimonic 
of sodium. oxide. 


H 2 + 

Water. ! 


2H 2 S 

Sulphuretted 
hydrogen. 




Sb 2 5 + 6NaIIO 

Antimonic Soda, 
oxide. 


= 


2Na 3 Sb0 4 + 

Antimoniate. 


2H 2 



In the hot solutions of these sulphur salts and oxygen salts sul- 
phide and oxide of antimony are soluble, and arc reprecipitated in 



ANTIMONY. 



181 



an indefinite state of combination, partially on cooling or wholly on 
the addition of acid. The acid also decomposes the oxysalts with 
precipitation of oxides, and the sulphur salts with precipitation of 
sulphides of antimony. The acid should be added to the liquids 
before much oxysulp'hide has deposited (that is, before the solution 
is cool) if uniformity of product is desired. 

2Na 3 SbS 3 + 3H 2 S0 4 = = 3Na,S0 4 + Sb 2 S 3 + 3H 2 S 

Sulphate of Antimonious Sulphuretted 
sodium. sulphide. hydrogen. 



3H 2 S0 4 

Sulphuric 
acid. 



2Na 3 Sb0 3 -f 

Antimonite of 
sodium. 

2Na 3 SbS 4 4 

Sulph-antimoniate 
of sodium. 

2Na 3 Sb0 4 -+ 

Antimoniate 
of sodium. 



3H. 2 S0 4 

Sulphuric 
acid. 

3H 2 S0 4 

Sulphuric 
acid. 

3H 2 S0 4 

Sulphuric 
acid. 



3Na 2 S0 4 

Sulphate of 
sodium. 

3Na 3 S0 4 

Sulphate of 
sodium. 

3Na 2 S0 4 

Sulphate of 
sodium. 



+ Sb 2 S 3 - 

Antimonious 
sulphide. 

+ Sb 2 3 - 

Antimonious 
oxide. 

+ Sb 2 S 5 

Antimonic 
sulphide. 

+ Sb 2 5 

Antimonic 
oxide. 



3H 2 

"Water. 

+ 3H 2 S 

Sulphuretted 
hydrogen. 

-f 3H 2 

Water. 



The oxide and sulphide indicated in these equations, together with 
excess of sulphide of antimony originally dissolved by the alkaline 
liquid, are all precipitated when the acid is added, and form the 
varieties of kermes. Kermes may be formed by union as well as by 
aqueous solution of the components. The student is strongly recom- 
mended carefully to study the foregoing paragraphs, for, although 
neither the official nor any other variety of kermes is itself of much 
importance in modern practical pharmacy, a thoughtful consideration 
of the chemistry will, by revealing chemical actions and analogies 
that are general, sow the seeds of chemical principles in the mind. 



The previous four synthetical reactions illustrate the official pro- 
cesses for the respective substances. The solution of chloride of 
antimony is only used in the preparation of oxide; the oxide, lie- 
sides its use in the preparation of tartar emetic, is mixed with twice 
its weight of phosphate of calcium (purified bone-earth) to form 
Prdvis Antimonialis, U. S. P., or u James s Powder. 

Sulphides and hydride of antimony are incidentally mentioned in 
the following analytical paragraphs. 

(h) Reaction having Analytical Interest (Tests). 
First Analytical Reaction. — Through an acidified antimonial 
solution pass sulphuretted hydrogen; an orange precipitate of 
amorphous sulphide of antimony falls. It has the same com- 
position as the crystalline black sulphide (Sb a S 3 )j into which, 
indeed, when dried, it is quickly converted by heat, lake sul- 
phide of arsenicum, it is soluble in alkaline solutions. Collect 
a portion on a filter, and, when well drained, add strong hydro- 
chloric acid ; it dissolves — unlike sulphide oi' arsenicum. 
16 



182 THE METALLIC RADICALS. 

A higher sulphide of antimony (Sb 2 S 5 ), corresponding to the 
higher sulphide of arsenicum, exists. It is formed on passing 
sulphuretted hydrogen through an acidified solution of the 
higher chloride (SbCl 5 ), or on boiling black sulphide of anti- 
mony and sulphur with an alkali, and decomposing the result- 
ing filtered liquid by an acid. 

Note. — The arsenious and antimonious compounds are those chiefly 
employed in medicine ; arseniates of sodium and iron are, however, 
sometimes employed. The arseniates and rarely an antimoniate are 
useful in analysis, and the antimonic chloride in chemical research. 
The higher compounds of both elements are noticed here chiefly to 
draw attention to the close analogy existing between arsenicum and 
antimony, an analogy carried out in the numerous other compounds 
of these elements. 

Second Analytical Reaction. — Dilute two or three drops of 
the solution of chloride of antimony with water ; a precipitate 
of oxychloride occurs, the formation of which has been ex- 
plained under the similar synthetical reaction. The occurrence 
of this precipitate distinguishes antimony from arsenicum, but 
is a reaction that cannot be fully relied upon in analysis, be- 
cause requiring the presence of too much material and the ob- 
servance of too many conditions. Add a sufficient quantity of 
hydrochloric acid to dissolve the precipitate, and boil a piece 
of copper in the solution, as directed in the corresponding test 
for arsenicum (vide page 170) ; antimony is deposited on the 
copper. Wash, dry, and heat the copper in a test-tube as be- 
fore ; the antimony, like the arsenicum, is volatilized off the 
copper and condenses on the side of the tube as white oxide, 
but the sublimate, from its low degree of volatility, condenses 
close to the copper ; moreover, it is destitute of crystalline cha- 
racter — that is to say, it is amorphous (a, a, without ; /M>p<p7], 
morphe, shape). 

Shake out the copper, and boil water in the tube for several 
minutes. Do the same with the arsenical sublimate similarly 
obtained. The deposit of arsenic slowly dissolves, and may be 
recognized in the solution by ammonio-nitrate of silver ; the 
antimonial sublimate is insoluble. 

Third Analytical Reaction. — Perform the experiments de- 
scribed under Marsh's test for arsenicum (pp. 170, 171), care- 
fully observing all the details there mentioned, but using a few 
drops of solution of chloride of antimony or tartar emetic in- 
stead of the arsenical solution. Antimoniuretted hydrogen, or 
hydride of antimony (SbH 3 ), is formed and decomposed in the 
same way as arseniuretted hydrogen. 



ANTIMONY. 183 

To one of the arsenicum spots on the porcelain lid (p. 171 ) 
add a drop of a solution of " chloride of lime " (bleaching- 
powder) ; it quickly dissolves. Do the same with an antimony 
spot ; it is unaffected. 

Heat more quickly causes the volatilization of an arsenicum than 
an antimony spot ; sulpfrydrate of ammonium more readily dissolves 
the antimony than the arsenicum. 

Boil water for several minutes in the beaker or wide test- 
tube containing the arsenious sublimate (page 171) ; it slowly 
dissolves, and may be recognized in the solution by the yellow 
precipitate given on the addition of solution of ammonio-nitrate 
of silver. The antimonial sublimate, similarly treated, does 
not dissolve. 

Pass a slow current of sulphuretted hydrogen through the 
delivery-tube removed from the hydrogen-apparatus (page 171), 
and, when the air may be considered to have been expelled from 
the tube, gently heat that portion containing the deposit of 
arsenicum ; the latter will be converted into a yellow sublimate 
of sulphide of arsenicum. Remove the tube from the sul- 
phuretted-hydrogen apparatus, and repeat the experiment with 
a similar antimony deposit ; it is converted into orange sul- 
phide of antimony, which, moreover, owing to inferior vola- 
tility, condenses nearer to the flame than sulphide of ar- 
senicum. 

Pass" dry hydrochloric acid gas through the two delivery- 
tubes. This is accomplished by adapting first one tube and 
then the other by a cork to the test-tube containing a few 
lumps of common salt, on which a little sulphuric acid is 
poured during the momentary removal of the cork. The sul- 
phide of antimony dissolves and disappears ; the sulphide of 
arsenicum is unaffected. 

Thorough conception of the chemistry of arsenicum and antimony 
will be obtained on constructing equations or diagrams descriptive of 
each of the foregoing reactions. 

Antidote. — The introduction of poisonous doses of antimo- 
nial s into the stomach is fortunately quickly followed by vom- 
iting. If vomiting has not occurred, or apparently to an in- 
sufficient extent, any form of tannic acid may be administered 
(infusion of tea, nutgalls, cinchona, oak-bark, or other astrin- 
gent solutions or tinctures), an insoluble tannate of antimony 
being formed, and absorption of the poison consequently some- 
what retarded. The stomach-pump must be applied as quickly 
as possible. 



184 THE METALLIC RADICALS. 

Recently precipitated moist ferric hydrate is also, according 
to T. and H. Smith, a perfect absorbent of antimony from its 
solutions, the chemical actions being probably, they say, similar 
to that which takes place between ferric hydrate and arsenious 
anhydride. It may be given in the form of a mixture of per- 
chloride of iron either with carbonate of sodium or with mag- 



These statements may be verified by mixing together the various 
substances, filtering, and testing the filtrate for antimony in the 
usual manner. 



Directions for applying the foregoing reactions to 
the analysis of an aqueous solution of salts of 
one of the elements arsenicum and antimony. 

Acidify the liquid with hydrochloric acid, and pass through 
it sulphuretted hydrogen — 

A yellow precipitate indicates arsenicum. 

An orange precipitate indicates antimony. 

The result may be confirmed by the application of other 
tests. 

Directions for applying the foregoing reactions to 
the analysis of an aqueous solution of salts of 
both Arsenicum and Antimony. 

Acidify a small portion of the liquid with hydrochloric acid, 
and pass through it sulphuretted hydrogen. 

Note I. — If the precipitate by sulphuretted hydrogen is unmis- 
takably orange, antimony may be put down as present, and arseni- 
cum only further sought by the application of FleitnianiVs test to 
fche solution of the sulphide in aqua regia* freed from sulphur by 
boiling, or, better, to the original solution. 

Note II. — Sulphide of antimony is far less readily soluble than 
sulphide of arsenicum in solution of carbonate of ammonium. But 
this fact possesses limited analytical value 5 for the color of the sul- 
phides is already sufficient to distinguish the one from the other 
when they are unmixed ; and when mixed, much sulphide of anti- 
mony will prevent a little sulphide of arsenicum from being dis- 
solved by the alkaline carbonate, while much sulphide of arsenicum 
will carry a little sulphide of antimony into the solution. When the 
proportions are, apparently, from the color of the precipitate, less 
wide, solution of carbonate of ammonium will be found useful in 

* Aqua Regia is a mixture of fifteen parts hydrochloric and four parts 
nitric acid. It was so called from its property of dissolving gold, the 
" king" of metals. 



ARSENICUM AND ANTIMONY. 185 

roughly separating the one sulphide from the- other. On filtering 
and neutralizing the alkaline solution by an acid, the yellow sulphide 
of arsenicum is reprecipitated. The orange sulphide of antimony 
will remain on the filter. 

Note III. — Solution of bisulphite of potassium is said by Wohler 
to be a good reagent for separating the sulphides of arsenicum 
and antimony, the former being soluble, the latter insoluble in 
the liquid. 

Note IV. — Another reagent for separating the sulphides of arsen- 
icum and antimony is strong hydrochloric acid. As little water as 
possible must be present. On boiling, the sulphide of antimony dis- 
solves, while the sulphide of arsenicum remains insoluble. The 
liquid slightly diluted, filtered, more water added, and sulphuretted 
hydrogen again transmitted, gives orange sulphide of antimony. 
The process should previously be tried on the precipitated mixed 
sulphides. The presence of arsenicum may be confirmed by the 
application of Fleitmann's test to the original solution. 

Note V. — If the precipitate by sulphuretted hydrogen is unmis- 
takably yellow, arsenicum may be put down as present, and any 
antimony detected by the previous or one of the following two pro- 
cesses. These two processes are rather long, and require much 
care in their performance, but are useful, because a small quantity 
of antimony in much arsenicum, or vice versa, may be detected by 
their means. 

First Process. — Generate hydrogen and pass it through a 
small wash-bottle containing solution of acetate of lead, to free 
the gas from any trace of sulphuretted hydrogen it may pos- 
sess, and then through a dilute solution of nitrate of silver con- 
tained in a test-tube. When the apparatus is in good working 
order, pour into the generating-bottle the solution to be ex- 
amined, adding it gradually to prevent violent action. After 
the gas has been passing for five or ten minutes, examine the 
contents of the nitrate-of-silver tube ; arsenicum, if present, 
will be found in the solution in the state of arsenious acid, 

AsH 3 + 3H 2 + 6AgN0 3 = H 3 As0 3 + 6HN0 3 + 3Ag 2 ; 

while antimony, if present, will be found in the black precipi- 
tate that has fallen, according to the following equation : — 

SbH 3 + 3AgN0 3 = SbAg 3 + 3HN0 3 . 

The arsenious radical may be detected in the clear, filtered, 
supernatant liquid, which still contains much nitrate of silver, 
by cautiously neutralizing with a very dilute solution of am- 
monia, or by adding a few drops of solution of ammonio-nitrate 
of silver, yellow arsenite of silver being produced. The anti- 
mony may be detected by washing the black precipitate, boil- 
ing it in an open dish with solution of tartaric acid, acidulating 
with hydrochloric acid, filtering, and passing sulphuretted hv- 



186 THE METALLIC RADICALS. 

drogen through the solution — the orange sulphide of antimony 
being precipitated (Hofmann). 

Second Process. — Obtain the metallic deposit in the middle 
of the delivery-tube, as already described under Marsh's test. 
Act on the deposit by sulphuretted hydrogen gas, and then by 
hydrochloric acid gas, as detailed in the third analytical reaction 
of antimony (p. 182). If both arsenicum and antimony are 
present, the deposit, after the action of sulphuretted hydrogen, 
will be found to be of two colors, the yellow sulphide of arseni- 
cum being usually further removed from the heated portion of 
the tube than the orange sulphide of antimony. Moreover, 
subsequent action of hydrochloric acid gas causes disappear- 
ance of the antimonial deposit, which is converted into chloride 
of antimony and carried off in the stream of gas. 

The chief objection to this process is the liability of the operator 
mistaking sulphur, deposited from the sulphuretted hydrogen gas 
by heat, for sulphide of arsenicum. But the presence or absence 
of arsenicum is easily confirmed by applying Fleitmann's test to the 
original solution, while the process is most useful for the detection 
of a small quantity of a salt of antimony when mixed with much 
of an arsenical compound. 



The laboratory student may now proceed to the analysis of aque- 
ous solution of salts of any of the metallic elements hitherto con- 
sidered. The method followed may be that for the separation of 
the previous three groups, sulphuretted hydrogen being first passed 
through the solution to throw out arsenicum and antimony. The 
whole scheme of analysis is given on the next page. Three or four 
solutions should be examined before proceeding to the last group of 
metals. 

Learners who have no opportunity of working at practical anal- 
ysis will gain much knowledge by endeavoring not to remember, 
but to understand these methods of separating "elements from each 
other in a solution containing several compounds. 



QUESTIONS AXD EXERCISES. 

2G9. What is the composition and source of the Black Aniimony 
of pharmacy? 

27<>. In what alloys is metallic antimony a characteristic ingre- 
dient? 

"271. What is the quantivalence of antimony as far as indicated 
by the formulae of the official preparations? 

272. By a diagram show how "Butter of antimony'* is prepared. 

273. Write out equations or diagrams expressive of the reactions 
which occur in converting chloride of antimony into oxide. 



QUESTIONS AND EXERCISES. 187 

274. What is the formula of Tartar Emetic ? 

275. Explain the official process for the preparation of Oxysul- 
phide of Antimony (Antimonium Sulphuratum, U. S. P.) by aid of 
diagrams. 

276. Give a comparative statement of the tests for arsenicum and 
antimony. 

277. How is antimony detected in the presence of arsenicum ? 

278. How may arsenicum and iron be distinguished analytically? 

279. Describe a method by which antimony, magnesium, and iron 
may be separated from each other. 

280. Draw out an analytical chart for the examination of an 
aqueous liquid containing salts of arsenicum, zinc, calcium, and 
ammonium. 



COPPER, MERCURY, LEAD, SILVER, 

These metals, like arsenicum and antimony, are precipitated from 
acidified solutions by sulphuretted hydrogen, in the form of sulphides ; 
but the sulphides, unlike those of arsenicum and antimony, are in- 
soluble in alkalies. The atom of copper is usually bivalent, Cu" ; 
mercury bivalent in the mercuric salts, Hg // , and univalent in the 
mercurous salts, Hg' ; lead sometimes quadrivalent, Pb 7/// , but gene- 
rally exerting only bivalent activity, Pb" ; and silver univalent, Ag'. 

COPPER. 

Symbol Cu. Atomic weight 63.4. 

Source. — The commonest ore of this metal is copper pyrites, a 
double sulphide of copper and iron, raised in Cornwall; Australia 
and Russia supply malachite, a mixed carbonate and hydrate ; much 
ore is also imported from Spain and from South America. It is 
smelted in enormous quantities at Swansea, South Wales, a locality 
peculiarly fitted for the operation on account of its proximity to the 
coal-fields and its position as a sea-coast town — these advantages at 
all times ensuring cheap fuel and freightage to the different metal- 
lurgical establishments. An economical method of smelting copper 
pyrites and other sulphides has recently been introduced by 1 loll- 
way. After the sulphide is once melted air is driven, not over, as 
usual, but through the mass ; the combustion of the sulphur then 
becomes self-supporting and is greatly accelerated. 

Alchemy. — The alchemists termed this metal Venus, perhaps on 
account of the beauty of its lustre, and gave it her symbol $, a com- 
pound hieroglyphic also indicating a mixture of gold and a certain 
hypothetical substance called acrimony ©, the corrosive nature oi' 
which was symbolized by the points of a Maltese cross. To this day 
the blue show-bottle in the shop-window of the pharmacist is occa- 
sionally ornamented by such a symbol, indicative, possibly, of the 
fact that the blue liquid in the vessel is a preparation of copper. 

Coinage. — The material of British copper coinage is now a bronze 
mixture composed, in 100 parts by weight, oi' 95 copper, 1 tin. and 
1 zinc, the same as in the copper coinage oi' France. The penny 



188 



THE METALLIC RADICALS. 



c A _s 

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t^&ls 






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g I 1 

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CD ^ K 

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c c x 5 , <u 

grS-Sffi'o* ci g © 

go g ^^^2 ^.S 

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1 a 2-H ^ 'l'~ §3 

>-> a^-r 5^^ - a 

* C -I- CO >T3 -M- ^ P-cT 
fc£ — « O C3 CS 



COPPER. 189 

is coined at the rate of 48 pence in one pound avoirdupois, of 7000 
grains, or 453.6 grammes ; the halfpenny at 80 in the pound avoir- 
dupois, and the farthing at 160. British bronze coins are a legal 
tender in payments to the amount of Is. 

Metallic Copper , U. S. P., occurs " in slender wire, or thin foil cut 
into strips." 

Quantivalence. — Copper forma two classes of salts ; in one the 
atom is bivalent (Cu // ), in the other it exerts univalent activity 
(Cu/). The former are of primary importance, the latter being 
for the most part unstable and wanting in technical interest. Their 
compounds are distinguished as cupric and cuprous 5 but those of 
the higher class only have general interest, and will be almost ex- 
clusively alluded to in the following paragraphs. Cuprous iodide 
(Cu 2 I 2 ) will subsequently be referred to as a convenient form in 
which to remove iodine from solution, while the formation of 
cuprous oxide (Cu 2 0), under given circumstances, will come under 
notice as an indicator of the presence of sugar in a liquid. 

Reactions having (a) Synthetical and (U) Analytical 
Interest. 

(a) Synthetical Reactions. 

The processes for the following salts include the only synthet- 
ical reactions having any medical or pharmaceutical interest : 
1, cupric oxide, the black oxide of copper, prepared by heating 
fragments of copper to low redness on a piece of earthenware in 
an open fire ; 2, cupric sulphate, the common sulphate of cop- 
per, prepared by boiling black oxide and about an equal weight 
of sulphuric acid in water, filtering, and setting aside the solu- 
tion so that crystals may form on cooling; and 3, ammonio- 
sulphate of copper, for the preparation of which see p. 174 ; 
also p. 189. 

Cu, + 2 = 2CuO 

Copper. Oxygen. Cupric oxide. 

CuO + H 2 S0 4 == CuS0 4 + 11,0 

Cupric oxide. Sulphuric acid. Cupric sulphate. Water. 

Sulphate of Copper (Cupri Sulphas, U. S. P.) (CuS0 4 ,5H 2 0), blut 
vitriol, brimstone, or cupric sulphate, is the only copper salt much 
used in pharmacy. It is a by-product in silver-refining (2Ag 2 S0 4 
Cu 2 = 2CuS0 4 -j-2Ag 2 ). A little is also formed in roasting copper 
pyrites. In the latter case some sulphide of iron and the sulphide 
of copper are oxidized to sulphates; but the low rod heat finally 
employed decomposes the sulphate of iron, while the sulphate of 
copper is unaffected; it is purified by crystallization from a hot 
aqueous solution, though frequently much sulphate o{' iron remains 
in the crystals. Sulphate of copper results on dissolving in diluted 
sulphuric acid the black oxide (CuO) obtained in annealing cop- 
per plates (see the foregoing equations); it may also be pre- 



190 _ THE METALLIC KADICALS. 

pared by boiling copper with three times its weight of sulphuric 
acid (2H 2 S0 4 + Cu = CuS0 4 + S0 2 + 2H 2 0), diluting, filtering, 
evaporating, and crystallizing. In this process a little black 
sulphide of copper is formed. 

Anhydrous Sulphate of Copper (CuS0 4 ) is a yellowish-white 
powder prepared by depriving the ordinary blue crystals of sulphate 
of copper of their water of crystallization by exposing them to a 
temperature of about 400° F. It is used in testing alcohol and 
similar spirituous liquids for water, becoming blue if the latter be 
present. 

Verdigris (from vcrde-gris, Sp. green-gray) is a Subacetate or 
Oxy acetate of Copper (B. P.) (Cu 2 02C 2 H 3 2 ), obtained by exposing 
alternate layers of copper and fermenting refuse grape-husks to the 
action of air. Digested with twice its weight of acetic acid and 
a little water, the mixture being evaporated to dryness and the 
residue dissolved in water, it forms a Solution of Acetate of Copper 
(Cu2C 2 IT 3 2 .II 2 0). from which deep-green prismatic ciystals of the 
acetate (Cupri Acetas, U. S. P.) may be obtained. 

The modes of forming cupric suljjhide, hydrate, oxide, ferrocyanide, 
and arsenite, as well as the precipitation of metallic copper, arc inci- 
dentally alluded to in the following analytical paragraphs. 

(b) Reactions having Analytical Interest {Tests). 

First Analytical Reaction. — Pass sulphuretted hydrogen 
through an acidified solution of a copper salt (sulphate, for ex- 
ample) ; black cupric sulphide (CuS) falls. 

Second Analytical Reaction. — Add sulph^drate of ammonium 
to an aqueous copper solution ; cupric sulphide is again pre- 
cipitated, insoluble in excess. 

Note. — Cupric sulphide is not altogether insoluble in sulphydrate 
of ammonium if free ammonia or much ammoniacal salt be present ; 
it is quite insoluble in the fixed alkaline sulphides. 

Third Analytical Reaction. — Immerse a piece of iron or 
steel, such as the point of a penknife or a piece of wire, in a 
few drops of a copper solution ; the copper is deposited, of cha- 
racteristic color, an equivalent quantity of iron passing into 
solution. 

By this reaction copper may be recovered on the larger scale from 
waste solutions, old hoop or other scrap iron being thrown into the 
liquors. 

Fourth Analytical Reaction. — Add ammonia to a cupric solu- 
tion ; cupric hydrate (Cu2HO) of a light -blue color is precipi- 
tated. Add excess of ammonia ; the precipitate is redissolved, 
forming a blue solution of ammonio-salt of copper, so deep in 
color as to render ammonia an exceedingly delicate test for this 
metal. 



COPPER. 191 

An ammonio-sulphate of copper may be obtained in large crystals 
by adding strongest solution of ammonia to powdered sulphate of 
copper until the salt is dissolved, placing the liquid in a test-glass 
or cylinder, cautiously pouring in twice its volume of strong alcohol 
or methylated spirit, taking care that the liquids do not become 
mixed, tying over the vessel with bladder, and setting aside for 
some weeks in a cool place (Wittstein.) The constitution of am- 
monio-sulphate and other ammonio-salts of copper and correspond- 
ing salts of silver will be alluded to in connection with " white pre- 
cipitate," the official " ammoniated mercury." 

Cuprum Ammoniatum is an ammonio-sulphate of copper pre- 
pared by rubbing together sulphate of copper and carbonate of am- 
monium until effervescence ceases, and drying the product. 

Fifth Analytical Reaction. — Add solution of potash or soda 
to a cupric solution ; cupric hydrate (Cu2HO) is precipitated, 
insoluble in excess. Boil the mixture in the test-tube ; the 
hydrate is decomposed, losing the elements of water, and be- 
coming the black anhydrous oxide (CuO). 

Sixth Analytical Reaction. — Add solution of ferrocyanide of 
potassium (K 4 Fcy) to an aqueous cupric solution ; a reddish- 
brown precipitate of cupric ferrocyanide (Cu 2 Fcy) falls. This 
is an extremely delicate test for copper. 

Seventh Analytical Reaction. — To a cupric solution add so- 
lution of arsenic, and cautiously neutralize with alkali ; green 
cupric arsenite (CuHAsO ; J falls. 

Note-. — This precipitate has been already mentioned under arsen- 
icum. An arsenicum salt is thus a test for copper as a copper salt 
is for arsenicum — a remark that may obviously be extended to most 
analytical reactions •, for the body acted upon characteristically by 
a reagent is as good a test for the reagent as the reagent is for it : 
indeed it becomes a reagent when the other body is the object of 
search. Most copper salts color flame green, the chloride blue. 

Antidotes. — In cases of poisoning by compounds of copper, 
iron filings should be administered, the action of which has just 
been explained (see third analytical reaction). Ferrocyanide 
of potassium may also be given (sec sixth analytical reaction). 
Albumen forms with copper a compound insoluble in water ; 
hence raw eggs should be swallowed, vomiting being induced, 
or the stomach-pump applied as speedily as possible. 



QUESTIONS AND EXERCISES. 

281. What are the analytical relations of copper, mercury, lead, 
and silver to each other and to arsenicum and antimony? 
2S2. Name the sources of copper. 






192 THE METALLIC RADICALS. 

283. What proportion of copper is contained in English and 
French "copper" coins? 

284. Give diagrams showing how Sulphate of Copper is prepared 
on the small and large scales. 

285. Work out a sum showing how much Crystallized Sulphate of 
Copper may be made from 100 parts of sulphide. — Ans. 26 \\ parts. 

286. How may Oxide of Copper be prepared ? 

287. Mention the formula of Verdigris. 

288. Name a good clinical test for copper. 

289. What is the analytical position of copper ? 

290. Mention the chief tests for copper. 

291. How may copper be separated from arsenicum? 

292. Why is finely divided iron an effective antidote in cases of 
poisoning by copper? 

MERCURY. 

Symbol Hg. Atomic weight 199.7. 
Molecular weight 199.7 (not double the atomic weight). 

Source. — Mercury occurs in nature as sulphide (HgS), forming 
the ore cinnabar (an Indian name expressive of something red), and 
is obtained from Spain, California, Eastern Hungary, China, Japan, 
and Peru. 

Preparation. — The metal is separated by roasting off the sulphur 
and then distilling, or, better, distilling with lime, which combines 
with and retains the sulphur. 

Properties. — Mercury (Hydrargyrum, U. S. P.) is a silver-white 
lustrous metal, liquid at common temperatures. It boils at 662° F., 
and at — 40° F. solidifies to a malleable mass of octahedral crystals. 
When quite free from other metals it does not tarnish, its globules 
roll freely over a sheet of white paper without leaving any streak or 
losing their spherical form, and when boiled with strong solution of 
sodium hyposulphite it does not lose its lustre and does not acquire 
more than a slightly yellowish shade. 

Formula. — The formula of the mercury molecule is Hg and not 
Hg 2 , because (at all events at the high temperature at which alone 
the weight of its vapor can be determined) two volumes, which if 
hydrogen would weigh two parts (H 2 ) or oxygen thirty-two parts 
(0. 2 ), in the case of mercury vapor weigh only two hundred parts 
(Hg) ; that is, only once the atomic weight, not twice. That 200, 
and not 100, is the atomic weight of mercury is shown by the fact 
that 200 is the minimum proportion relative to 1 of hydrogen in 
which mercury combines, and by its relations to heat. Still it is 
difficult to imagine an atom existing in the free state in nature ; and 
the suggestion has been made that (as is proved to be the case with 
sulphur) mercury, as we know it, is in abnormal condition, and that 
if the weight of its vapor could be taken at a lower temperature, or 
under some other condition, its molecular weight might be found to 
be 400. Similar remarks may be made respecting zinc, the molec- 
ular weight of which, so far as we know, is identical with its atomic 
weight. 



MERCURY. 193 

Medicinal Compounds. — The compounds of mercury used in medi- 
cine are all obtained from the metal. The metal itself, rubbed with 
chalk and sugar of milk, or with confection of roses and powdered 
liquorice-root, or with lard and suet, until globules are not visible 
to the unaided eye, is often used in medicine. The preparations are : 
the Hydrargyrum cum Creta, U. S. P., or "Gray Powder •," Massa 
Hydrargyria U. S. P., " Blue Mass " or " Blue Pill ;" and Unguentum 
Hydrargyria U. S. P., or " Blue Ointment." There are also a Com- 
pound Ointment, a Plaster of Mercury, a Plaster of Ammoniacum 
and Mercury, a Liniment, and a Suppository. Their therapeutic 
effects are probably due not to the large quantity of metallic mercury 
in them, but to the small quantities of black and red oxide which 
occur in them through the action of the oxygen of the air on the 
finely-divided metal. The proportion of oxide or oxides varies ac 
cording to the age of the specimen. 

All these medicinal preparations of metallic mercury are indefinite 
and unsatisfactory, and that through no fault of the pharmacist. 
They much need investigation by therapeutists. Here, as in many 
similar cases, if Medicine would first ascertain her own requirements 
and then make them known, her handmaid Pharmacy would be found 
quite capable of supplying them. 

Mercurous and Mercuric Compounds. — Mercury combines with 
other elements and radicals in two proportions ; those compounds 
in which the other, acidulous, radicals are in the lesser amount 
are termed mercurous, the higher being mercuric. Thus, calomel 
(HgCl*) is mercurous chloride, while corrosive sublimate (HgCl,) 
is mercuric chloride. In every pair of mercuric compounds the 
mercuric contains twice as much complementary radical, in propor- 
tion to the mercury, as the mercurous. 

Note on Nomenclature. — The remarks made concerning the two 
classes of iron salts, ferrous and ferric (p. 140), apply in the main to 
the two series of mercury salts. The latter are systematically dis- 
tinguished in most modern works by the terms mercurous and mer- 
curic In the British and United States Pharmacopoeias, however, 
which include only a few in comparison with the whole number of 
mercury salts, older and more strongly contrasted names are em- 
ployed, thus : — 

Systematic names. Official names. 

Mercurous iodide Green iodide of mercury. 

Mercuric iodide Red iodide of mercury. 

Mercurous nitrate Not mentioned. 

Mercuric nitrate Nitrate of mercury. 

Mercurous sulphate .... Not mentioned. 

Mercuric sulphate Sulphate of mercury. 

*The specific gravity of the vapor of calomel, and the fact that the 
salt is not decomposed at the temperature at which its specific gravity 
is taken, indicate that the formula of calomel is EfgCl, and not 
H&CL, 

17 



194 THE METALLIC RADICALS. 

Systematic names. Official names. 

Mercurous chloride .... Subchloride of mercury. 

Mercuric chloride Perchloride of mercury. 

Mercurous oxide Black oxide of mercury. 

Mercuric oxide Red oxide of mercury. 

Specific gravity. — Mercury is 13.6 times as heavy as water. 

Amalgams. — The compound formed infusing metals together is 
usually termed an alloy {ad and ligo, to bind) ; but if mercury is a 
constituent, an amalgam {/Lta?,ay/ia, malagma, from /ua/A(j(ju, malasso, 
to soften, the presence of mercury lowering the melting-point of 
such a mixture). Most metals, even hydrogen, according to Leow, 
form amalgams. 

Reactions having (a) Synthetical and (b) Analytical 
Interest. 

(a) Synthetical Reactions. 
The Two Iodides. 
First Synthetical Reaction. — Rub together a small quantity 
of mercury and iodine, controlling the rapidity of combination 
by adding, previously, and afterward occasionally, a few drops 
of spirit of wine, which, by evaporation, absorbs heat, and 
thus keeps down temperature. The product is either mercuric 
iodide, mercurous iodide, or a mixture of the two, as well as 
mercury or iodine if excess of either has been employed. If 
the two elements have been previously weighed in single atom- 
ic proportions, 200 of mercury to 127 of iodine (about 8 to 5, 
or 1 ounce of mercury to 278 grains of iodine), the mercurous 
or green (grayish-green) iodide results (Hgl) {Hydrargyria lo- 
didum Viride, U. S. P.) ; if in the proportion of one atom of 
mercury to two atoms of iodine (200 to twice 127, or about 4 
to 5), the mercuric or red iodide, Hgl 2 , results, an iodide that 
is also official, but made in another way. (See page 195.) 
The green iodide should be made and dried (without heat) 
with as little exposure to light as possible. The product 
should be well washed with alcohol to remove mercuric iodide. 

Mercurous iodide is decomposed slowly by light, and quickly by 
heat, into mercuric iodide and mercury. Mercuric iodide occurring 
as an impurity in mercurous iodide may be detected by digesting in 
ether (in which mercurous iodide is insoluble), filtering and evap- 
orating to dryness ; mercuric iodide remains. Mercuric iodide is 
stable, and may be sublimed in scarlet crystals without decomposi- 
tion. (For details of the method by which a specimen of the crystals 
may be obtained, and the precautions to be observed, vide " Corro- 
sive Sublimate," p. 199.) 

Relation of Mercuric Iodide to Light. — In condensing, mercuric 






MERCURY. 195 

iodide is at first yellow, afterwards acquiring its characteristic scar- 
let color. This may be shown by smearing or rubbing a sheet of 
white paper with the red iodide, and then holding the sheet before a 
fire or over a flame for a few seconds. As soon as the paper becomes 
hot the red instantly changes to yellow, and the salt does not quickly 
regain its red color, even when cold, if the paper is carefully handled. 
But if a mark be made across the sheet with anything at hand, or the 
salt be pressed or rubbed in any way, the portions touched immedi- 
ately return to the scarlet condition. According to Warrington, 
this change is consequent upon rhomboidal crystals being converted 
into octahedra with a square base, and will serve as an excellent 
illustration of the influence of physical structure in causing color. 
The yellow modification so acts on the rays of white light shining on 
its particles as to absorb the violet and reflect the complementary 
* hue, the yellow, which, entering the eye of the observer, strikes his 
retina, and thus conveys to the brain the impression of yellowness -, 
and the red modification, though actually the same chemical sub- 
stance, is sufficiently different in the structure of its particles to 
absorb the green constituent of white light and reflect the comple- 
mentary ray, the red. 

Illustration of the Chemical Law of Multiple Proportions (p. 48). 
— Applying the atomic theory to the above iodides, it will at once be 
apparent why mercury and iodine should combine in the proportion 
of 200 of mercury with either 127 or 254 of iodine, and not with any 
intermediate quantity. For it is part of that theory that masses are 
composed of atoms, and that atoms are indivisible ; and that the 
weight of the atom of mercury is to that of iodine as 200 is to 127. 
Mercury and iodine can only combine, therefore, in atomic propor- 
tions, atom to atom (which is the same as 200 to 127), or one atom 
to two atoms (which is the same as 200 to 254). To attempt to com- 
bine them in any intermediate proportion would be useless ; a mere 
mixture of the two iodides would result. A higher proportion of 
mercury than 200 to 127 of iodine gives but a mixture of mercurous 
iodide and mercury; a higher proportion of iodine than 254 to 200 
of mercury gives but a mixture of mercuric iodide and iodine. Or, 
for example, 200 grains of mercury, mixed with, say, 200 of iodine, 
would yield 139 grains of mercurous iodide and 261 grains of mer- 
curic iodide; for the 200 grains of mercury uniting with 127 grains 
of the iodine give, for the moment, 327 grains of mercurous iodide 
and 73 grains of iodine still free. The 73 grains of iodine will im- 
mediately unite with 188 grains of the mercurous iodide (for if 127 
of I require 327 of llgl to form IIgI 2 , 73 will require 188), and form 
261 grains of mercuric iodide, diminishing the 327 grains of mer- 
curous iodide to 139 grains. 

Preparation of Red Iodide of Mercury by precipitation. — To 
a few drops of a solution of a mercuric salt (corrosive subli- 
mate, for example), add solution of iodide of potassium, drop 
by drop; a precipitate of mercuric iodide, Hgl 2 , forms, and at 
first quickly redissolves, but is permanent when sufficient iodide 



196 THE METALLIC RADICALS. 

of potassium has been added. Continue the addition of iodide 
of potassium ; the precipitate is once more redissolved. 



HgCl 2 


+ 


2KI = 


= Hgl 2 


+ 


2KC1 


Mercuric 




Iodide of 


Mercuric 




Chloride of 


chloride. 




potassium. 


iodide. 




potassium. 



Note. — When first precipitated, mercuric iodide is yellowish-red, 
but soon changes to a beautiful scarlet. Its solubility either in solu- 
tion of the mercuric salt or in solution of iodide of potassium renders 
the detection of a small quantity of a mercuric salt by iodide of 
potassium, or a small quantity of an iodide by a mercuric solution, 
difficult, and hence lessens the value of the reaction as a test. But 
the reaction has synthetical interest, the method by precipitation 
being that adopted in the British and United States Pharmacopoeias 
{Hydrargyri Iodidum Rubrum, U. S. P.). Mercuric iodide thus made 
nas the same composition as that prepared by direct combination of 
its elements. Equivalent proportions of the two salts must be used 
in making the preparation (IIgCl 2 — 271 ; 2KI — 332). About 4 
parts of corrosive sublimate are dissolved in 50 or 60 of water 
(warmth quickens solution), and 5 of iodide of potassium in 15 or 
20 of water, the solutions mixed, and the precipitate collected on a 
filter, drained, washed twice with distilled water, and dried on a 
plate over a water-bath. Mercuric nitrate, which is more soluble, 
and therefore somewhat more convenient for use on the large scale, 
may be used instead of the mercuric chloride. The mercury in mer- 
curic or mercurous iodide is set free and sublimes in globules on heat- 
ing either powder with dried carbonate of sodium in a test-tube ; the 
iodine may be detected by digesting with solution of soda, filtering, 
and to the solution of iodide of sodium thus formed adding starch 
paste and acidulating with nitrous acid, when blue iodide of starch 
results. Mercuric iodide is insoluble in water, slightly soluble in 
alcohol, tolerably soluble in ether. Precipitated red iodide of mer- 
cury mixed with white wax, lard, and oil, forms the Unguent urn 
Hydrargyri Iodidi Rubri, B. P. 100 parts of a 5-per cent, solution 
of mercuric chloride with 367 parts of a 5-per cent, solution of iodide 
of potassium forms the " Test Solution of Iodide of Mercury and 
Potassium," U. S. P. 

The Two Nitrates. 

Second Synthetical Reaction. — Place a globule of mercury, 
about half the size of a pea, in a test-tube ; add twenty or 
thirty drops of nitric acid; boil slowly until red fumes (nitric 
oxide, NO) no longer form ; set aside. On cooling, if a globule 
of mercury still remains in the tube, crystals of mercurous 
nitrate separate. These may be dissolved in water slightly 
acidulated by nitric acid. The solution may be retained for 
subsequent analytical operations. 

Hg 3 + 4HN0 3 = 3HgN0 3 + 2H 2 4- NO. 

Third Synthetical Reaction. — Place mercury in excess of 



MERCURY. 197 

strong nitric acid, and warm the mixture ; mercuric nitrate is 
formed, and will be deposited in crystals as the solution cools. 
Or, to crystals of mercurous nitrate add nitric acid and boil 
until red fumes cease to form. Retain the product for a sub- 
sequent experiment. 

It will be seen that when mercury and nitric acid are boiled 
together mercurous nitrate is formed if the mercury be in excess, 
while mercuric nitrate is produced if the acid preponderate. 

The mercuric nitrates vary somewhat in composition, according to 
the proportion, strength, and temperature of the acid used in their 
formation. A mercuric nitrate may be obtained having the formula 
Hg2N0 3 . 

Hg 3 + 8HNO ? = 3(Hg2N0 3 ) + 2NO + 4H 2 

Mercury. Nitric acid. Mercuric nitrate. Nitric oxide. Water. 

Mercuric Oxynitrates. — From the normal mercuric nitrate several 
oxynitrates may be obtained. Thus on merely evaporating a solu- 
tion of mercuric nitrate, and cooling, crystals having the formula 
Hg 6 3 6N0 3 are deposited. The latter, by washing with cold water, 
yield a yellow pulverulent oxynitrate, Hg 6 4 4N0 3 : mixed with lard, 
this has sometimes been used as an ointment. Boiled in water, the 
yellow gives a brick-red oxynitrate, Hg 6 5 2N0 3 . 

The pharmacopceial preparations of mercuric nitrate are Liquor 
Hydrargyri Nitratis, U. S. P., containing half its weight of mercu- 
ric nitrate and free acid, sp. gr. 2.100, and Unguentum Hydrargyri 
Nitratis, U. S. P. The former is made by placing 40 parts of red 
oxide of mercury in 45 parts of nitric acid diluted with 15 parts of 
water. " 

HgO + 2IIN0 3 = Hg2N0 3 + II 2 0. 

The Unguentum or "Citrine Ointment" is made by oxidizing lard 
oil with nitric acid, and then adding a solution of mercury in nitric 
acid. 

The Two Sulphates. 

Fourth Synthetical Reaction. — Boil two or three grains of 
mercury with a few drops of strong sulphuric acid in a test- 
tube, or, better, small dish ; sulphurous acid gas (S0 2 ) is 
evolved, and mercuric sulphate or persulphate of mercury {Hy- 
drargyri Persulphas, B. P.) (HgSOj) results — a white heavy 
crystalline powder. 



Hg + 


2H 2 SO< = 


= HgSO, 


-f so 2 


+ 


2ILO 


ercury. 


Sulphuric 


Mercuric 


Sulphuro 




Water. 




acid. 


t sulphate. 


acid gas 







Between two and three ounces of mercuric sulphate may be 
prepared from a fluidrachni of mercury and a fluidounce oi' sul- 
phuric acid boiled together in a small dish. These are the 
official proportions. The operation is completed and any ex- 

1 7 * 



198 THE METALLIC RADICALS. 

cess of acid removed by evaporating the mixture of metal and 
liquid to dryness, either in the open air or in a fume-chamber, 
sulphuric acid vapors being excessively irritating to the mucous 
membrane of the nose and throat ; dry crystalline mercuric 
sulphate remains. If residual particles of mercury are ob- 
served, the mass should be dampened with sulphuric acid and 
again heated. 

By-products. — In chemical manufactories, secondary products, 
such as the sulphurous gas of the above reaction, are termed by- 
products, and, if of value, are utilized. In the present case the 
gas is of no immediate use, and is therefore allowed to escape. 
When very pure sulphurous acid gas is required for experiments 
on the small scale, this would be the best method of making it, a 
delivery -tube being adapted by a cork to the mouth of a flask con- 
taining the acid and metal. The sulphate of mercury would then 
become the by-product. 

Mercuric Oxysulphate. — Water decomposes mercuric sulphate into 
a soluble acid salt and an insoluble yellow oxysulphate (Hg 3 2 S0 4 ). 
The latter is called Turpeth mineral, from its resemblance in color to 
vegetable turpeth, the powdered root of Ipomcea turpethum, an Indian 
substitute for jalap. The yellow sulphate or subsulphate of mer- 
cury (Hydrargyri Sub sulphas Flavus, U. S. P.) is official. It should 
be entirely soluble in 20 parts of hydrochloric acid. 

Fifth Synthetical Reaction. — Rub a portion of the dry mer- 
curic sulphate of the previous reaction with as. much mercury 
as it already contains ; the product, when the two have thor- 
oughly blended, is mercurous sulphate (Hg\>S0 4 ) : it may be 
retained for a subsequent experiment. 

Molecular Weight. — The exact proportion of mercury to sulphate 
is merely a matter of calculation ; for the combining proportion of a 
compound (if it possess any combining power) is the sum of the com- 
bining proportions of its constituents. In other words, the combining 
weight of a molecule is simply the sum of the weights of its constituent 
atoms, or, more generally, the molecular weight of a compound is the 
sum of the atomic weights of its elements. In accordance with this 
rule (sometimes called the fourth law of chemical combination, 
though only a deduction from the first — p. 47), 296 of mercuric 
sulphate and 200 of mercury (about 3 to 2) are the exact propor- 
tions necessary to the formation of mercurous sulphate. 

The Two Chlorides. 

Sixth Synthetical Reaction. — Mix thoroughly a few grains 
of dry mercuric sulphate with about four-fifths its weight of 
chloride of sodium, and heat the mixture slowly in a test- 
tube in a fume-chamber ; mercuric chloride (HgCl 2 ), or cor- 
rosive sublimate, bichloride or perchloride of mercury {Hy- 
drargyri Perchloridum, B. P., Hydrargyri Chlor'olum Corro- 



MERCURY. 



199 



sivum, U. S. P.), sublimes and con- Fig. 36. 

denses in the upper part of the 
tube in heavy colorless crystals or 
a crystalline mass. Somewhat larger 
quantities (in the proportion of 20 of 
sulphate to 16 of salt, and, vide in- 
fra, 1 of a black oxide of manganese) 
may be sublimed in a pair of two- 
ounce or three-ounce round-bottomed 
gallipots, the one inverted over the 
other, and the joint luted by moist fire- 
clay (the powdered clay kneaded with f§J 
water to the consistence of dough). 
The luting having been allowed to 
dry (somewhat slowly, to avoid 
cracks), the pots are placed upright on a sand-tray (plate-shape 
answers very well), sand piled round the lower and a portion 
of the upper pot, and the whole heated over a good-sized gas- 
flame (if an air-gas flame, it should be an inch and a half wide 
and four or five inches long) for an hour or more in a fume- 
chamber (see fig. 36 — pots raised to show joint). Eed Iodide 
of Mercury and Calomel may be sublimed in the same way. 
The former requires less, the latter more, heat than corrosive 
sublimate. 




HgS0 4 


+ 


2NaCl = 


= HgCI, 


+ 


Na,SO, 


Mercuric 




Chloride of 


Mercuric 




Sulphate of 


sulphate. 




sodium. 


chloride. 




sodium. 



Note. — If the mercuric sulphate contain any mercurous sulphate, 
some calomel may be formed. This result will be avoided if '2 or 3 
per cent, of black oxide of manganese be previously mixed with the 
ingredients, the action of which is to eliminate chlorine from the 
excess of chloride of sodium used in the process, the chlorine eon- 
verting any calomel into corrosive sublimate. Manganate of sodium 
and a lower oxide of manganese are simultaneously produced. 

Precaution. — The operation is directed to be conducted with care 
in a fume-chamber, because the vapor of corrosive sublimate, which 
might possibly escape, is very acrid and highly poisonous. Its vul- 
gar name is indicative of its properties. It slowly volatilizes at 
warm temperatures. 

Ten grains of pcrchloride of mercury and the same quantity oC 
chloride of ammonium in one pint of water form the Liquor Hydrar- 
gyri Perchloridi, B. P. A dilute aqueous solution ol' perchloride o[' 
mercury is liable to decomposition, calomel being precipitated, water 
decomposed, hydrochloric acid formed, and oxygen gas evolved. The 
presence of excess of chloride of ammonium, with a portion of which 
the mercuric chloride forms a stable double salt, prevents the decom- 
position. 



200 THE METALLIC RADICALS. 

Seventh Synthetical Reaction. — Mix a few grains of the 
mercurous sulphate of the fifth reaction with about a third of 
its weight of chloride of sodium, and sublime in a test-tube ; 
crystalline mercurous chloride (HgCl) or calomel (Hydrargyri 
Sirf'cJilorfdum, B. P., Hydrargyri Chloridum Mite, U. S. P.) 
results. Larger quantities may be prepared in the manner 
directed for corrosive sublimate, a somewhat higher tempera- 
ture being employed ; similar precaution must also be observed. 
The proportions are 10 of mercuric sulphate to 7 of mercury 
and 5 of dry chloride of sodium. " Moisten the sulphate of 
mercury with some of the water, and rub it and the mercury 
together until globules are no longer visible ; add the chloride 
of sodium, and thoroughly mix the whole by continued tritu- 
ration. When dry, sublime by a suitable apparatus into a 
chamber of such a size that the calomel, instead of adhering 
to its sides as a crystalline crust, shall fall as a fine (dull-white) 
powder on its floor, Wash this powder with boiling distilled 
water until the washings cease to be darkened by a drop of 
sulphvdrate of ammonium. Finally, dry at a temperature not 
exceeding 212° F." 

Hg 2 S0 4 + 2NaCl = 2HgCl + Na. 2 S0 4 

Mercurous Chloride of Mercurous Sulphate of 

sulphate. sodium. chloride. sodium. 

The term calomel {xa7.bg, kalos, good, and /u&ag, melas, black) is 
said to relate to the use of the salt as a good remedy for black bile, 
but probably was simply indicative of the esteem in which black 
sulphide of mercury was held, the compound to which the name 
calomel was first applied. 

Test for corrosive sublimate in calomel. — If the mercurous sul- 
phate contains mercuric sulphate, some mercuric chloride will also 
be formed. Corrosive sublimate is soluble in water, calomel insol- 
uble ; the presence of the former may therefore be proved by boiling 
a few grains of the calomel in distilled water, filtering and testing 
by sulphuretted hydrogen or sulphydrate of ammonium as described 
hereafter. If corrosive sublimate is present, the whole bulk of the 
calomel must be washed with hot distilled water till the filtrate 
ceases to give any indications of mercury. Corrosive sublimate is 
more soluble in alcohol, and still more in ether ; calomel insoluble. 
Ether in which calomel has been digested should, therefore, after 
filtration, yield no residue on evaporation. Calomel is converted 
by hydrocyanic acid into mercuric salt, and a black powder readily 
yielding metallic mercury. Powell and Bayne have shown that a 
certain proportion of hydrochloric acid arrests this action. 

Note. — The above process is that of the Pharmacopoeia ; but cal- 
omel may also be made by other methods. Calomel mixed with lard 
forms the Unguentum Hydrargyri Subchtoridi, B. P., with sulphu- 
rated antimony, guaiaeum resin, and mucilage of tragacanth the 
PUvlce Antimonii Composite, U. S. P., or " Plummers Pills," and 



MERCURY. 201 

with colocynth, jalap, and gamboge the Pilulce Catharticce Compo- 
site, U. S. P. 

The Two Oxides. 
Eighth Synthetical Reaction. — Evaporate the mercuric nitrate 
of the third reaction to dryness in a small dish in a fume- 
chamber, or in the open air if more than a few grains have 
been prepared, and heat the residue till no more fumes are 
evolved ; red mercuric oxide (HgO), " Red Precipitate," the 
Red Oxide of Mercury (Hydrargyri Oxidum Rubriim, U. S. P.), 
remains. 

2(Hg2N0 3 ) = 2HgO + 4N0 2 + 2 

Mercuric nitrate. Mercuric oxide. Nitric peroxide. Oxygen. 

The nitric constituents of the salt maybe partially economized by 
previously thoroughly mixing with the dry mercuric nitrate as much 
mercury as is used in its preparation, or as much as it already con- 
tains (ascertained by calculation from the atomic weights and the 
weight of nitrate under operation, as in making mercurous sulphate 
p. 198), and well heating the mixture. In this case the free mercury 
is also converted into mercuric oxide. This is the official process, 
the Pharmacopoeial quantities being four ounces of mercury dissolved 
in four and a half fluidounces of nitric acid diluted with two ounces 
of water, the solution evaporated to dryness, the residue thoroughly 
mixed with four ounces of mercury, and the whole heated until acid 
vapors cease to be evolved. (Mercuric oxide is tested for nitrate by 
heating a little of the sample in a test-tube, when orange nitrous 
vapors" are produced and are visible in the upper part of the tube, 
if nitrate is present.) 

Hg2N0 3 + Hg = 2HgO + 2N0 2 

Mercuric nitrate. Mercury. Mercuric oxide. Nitric peroxide. 

Mercuric oxide is an orange-red powder, more or less crystalline 
according to the extent to which it may have been stirred during 
preparation from the nitrate, much rubbing giving the crystals a 
pulverulent character. Mercuric oxide, in contact with oxidiz- 
able organic matter, is liable to reduction to black or mercurous 
oxide. 

Ninth Synthetical Reaction. — To solution of potash or soda, 
or lime-water, in a test-tube or larger vessel, add solution of 
corrosive sublimate or of mercuric nitrate; yellow oxide of 
mercury (Hydrargyri Oxidum Flavum, U. S. P.), or yellow 
mercuric oxide (HgO), is precipitated. 

HgCl a + 2KIIO = HgO + 2KC1 + 11,0 

Mercuric Hydrate of Mercuric Chlorideof Water, 

chloride. potassium. oxide. potassium. 

The precipitate only differs physically from the red mercuric oxide ; 

the yellow is in a more minute state of division than the red. Mcr- 



202 THE METALLIC RADICALS. 

curie oxide is very slightly soluble in water, but sufficiently so to 
communicate a decidedly metallic taste. 

Tenth Synthetical Reaction. — To calomel add solution of pot- 
ash or soda, or lime-water ; black oxide of mercury, or mer- 
curous oxide (Hg 2 0) is produced, and may be filtered off, 
washed, and dried. (This reaction and the formation of a 
white curdy precipitate, on the addition of solution of nitrate 
of silver to the filtrate from the mercurous oxide, acidified by 
nitric acid, form sufficient evidence of a powder being or con- 
taining calomel. The curdy precipitate is chloride of silver.). 

Thirty grains of calomel to ten ounces of lime-water form the Lotio 
Hydrargyri Nigra, B. P. 

2HgCl + Ca2HO = Hg 2 + CaCL 2 + H 2 

Mercurous Hydrate of Mercurous Chloride of Water. 

chloride. calcium. oxide. calcium. 

(h) Analytical Reactions ( Tests). 

(The mercury occurring as mercuric or mercurous salts.) 

First Analytical Reaction. — The Copper Test. Deposition 
of mercury upon, and sublimation from copper. — Place a small 
piece of bright copper, about half an inch long and a quarter 
of an inch broad, in a solution of any salt of mercury, mer- 
curous or mercuric, and heat in a test-tube ; the copper be- 
comes coated with mercury in a fine state of division. (The 
absence of any notable quantity of nitric acid must be insured 
or the copper itself will be dissolved. See notes below.) Pour 
away the supernatant liquid from the copper, wash the latter 
once or twice by pouring water into, and then out of, the tube, 
remove the metal, take off excess of water by gentle pressure 
in a piece of filter-paper, dry the copper by passing it quickly 
through a flame, holding it by the fingers ; finall}', place the 
copper in a dry narrow test-tube, and heat to redness in a flame, 
the tube being held almost horizontally ; the mercury sublimes 
and condenses as a whitish sublimate of minute globules on the 
cool part of the tube outside the flame. The globules aggre- 
gate on gently pressing with a glass rod, and are especially 
visible where flattened between the rod and the side of the test- 
tube. 

Notes on the Test. — This is a valuable test, for several reasons : 
It is very delicate when performed with care. It brings before the 
observer the element itself — one which from its metallic lustre and 
fluidity cannot be mistaken for any other. It separates the element 
Loth from mercurous and mercuric salts. Mercury can in this way 



MERCURY. 203 

readily be eliminated in the presence of most other substances, or- 
ganic or inorganic. 

In performing the test the presence of any quantity of nitric acid 
may be avoided by adding an alkali until a slight permanent 
precipitate appears, and then reacidifying with a few drops of 
acetic or hydrochloric acid ; or by concentrating in an evap- 
orating-dish after adding a little sulphuric acid, and then re- 
diluting. 

Tests continued. (The mercury occurring as mercuric salt.) 

Second Analytical Reaction. — To a few drops of a solution 
of a mercuric salt (corrosive sublimate, for example) add solu- 
tion of iodide of potassium, drop by drop ; a precipitate of mer- 
curic iodide (Hgl 2 ) forms, and at first quickly redissolves, but 
is permanent when sufficient iodide of potassium has been 
added. Continue the addition of iodide of potassium ; the pre- 
cipitate is once more redissolved. 

Third Analytical Reaction. — Add a solution of mercuric salt 
to solution of ammonia, taking care that the mixture, after well 
stirring, still smells of ammonia ; a white precipitate falls. 

Ammoniated Mercury. 

Performed in a test-tube, this reaction is a very delicate test of 
the presence of a mercuric salt ; performed in larger vessels, the 
mercuric salt being corrosive sublimate (3 ounces dissolved in 3 pints 
of distilled water, the solution poured into 4 fluidounces of Solution 
of Ammonia, and the precipitate washed and dried over a water- 
bath), it is the usual process for the preparation of " white precipi- 
tate," the old " ammonio-chloride," or " amido-chloride of mercury" 
(so called because then considered to be a compound of mercury 
with chlorine and with amidogen, NH 2 , or HgCl 2 , Hg2NH 2 , chloride 
and amide of mercury), now known as Ammoniated Mercury {Hy- 
drargyrum Ammoniatum, U. S. P.). 

Constitution of Ammoniated Mercury. — This precipitate is con- 
sidered to be the chloride of mercuric ammonium (NH 2 Hg // Cl) — 
that is, chloride of ammonium (NH 4 C1), in which two univalent atoraa 
of hydrogen are replaced by one bivalent atom of mercury. 

HgCl 2 + 2NIIJIO = NITJIg^Cl + NII 4 C1 + 2II 2 

Mercui'ic Ammonia. "White Chloride of Water. 

chloride. precipitate." ammonium. 

Varieties of Ammoniated Mercury. — If the order of mixing be 
reversed, and ammonia be added to solution of mercuric chloride, 
a double chloride of mercuric-ammonium and mercury results 
(NH 8 HgCl,HgCl 2 ) : it contains 76.55 per cent, of mercury. Pre- 
viously to the year 182o, "white precipitate" was officially made by 
adding a fixed alkali to a solution of equal parts oi' corrosive subli- 
mate and sal-ammoniac ; this gave a double chloride of mercuric am- 



204 



THE METALLIC RADICALS. 



mouium and ammonium (NH 2 HgCl,NH 4 Cl), containing 65.57 per 
cent, of mercury. This compound is now known as u fusible white 
precipitate," because at a temperature somewhat below redness it 
fuses and then volatilizes. The "white precipitate" which has been 
official since 1826 contains 79.52 per cent, of mercury. The true 
compound may be distinguished as " infusible white precipitate," 
from the fact that when heated it volatilizes without fusing. An 
ointment of this body is official {Unguentum Hydrargyri Ammo- 
niati, U. S. P.). Prolonged washing with water converts " white 
precipitate" into a yellowish compound (XH 2 HgCl,HgO) ; hence 
the official preparation is seldom thoroughly freed from the chloride 
of ammonium which is formed during its manufacture, and which, 
if present in larger proportion than seven or eight per cent., gives 
to it the character of partial or complete fusibility. With iodine, 
chlorine, or bromine, white precipitate may yield the highly explo- 
sive iodide, chloride, or bromide of nitrogen. 

Note. — Chloride of mercuric-ammonium is only one member of a 
large class of compounds derivable from the various salts of ammo- 
nium by displacement of atoms of hydrogen in the molecules by 
other atoms. The composition of the chloride of mercurous-ammo- 
nium (see next page) and of ammonio-nitrate of silver is consistent 
with this view. In these formulas ammonium is symbolized by NH 4 
or Am indifferently. The use of the latter promotes clearness in the 
formulae, but it must only be employed when the ammonium acts 
like an elementary radical. 



N 



f H l 


f H § / 1 


i u 


*\¥\ 


IhJ 


Ih J 


Chloride of 


Chloride of 


common 


mercurous- 


ammonium. 


ammonium. 



CI 



N 



CI 



Chloride of 
mercuric- 
ammonium. 



N 



Ag 
Am 
II 
II 



NO, 



Nitrate of 
argent-ammon- 

ammonium. 



The composition of the ammonio-sulphates of copper (pp. 173 and 
189) is consistent with the second and third of the following for- 
mulae, the first being that of sulphate of ammonium : — 



51 

ft- 



so, 



Am. 
H, ' 
II, 



S0 4 



Cu" 
Am 2 
Am 2 
II 2 



SO, 



The iodide of dimercuric ammonium (NHg^I) is formed in test- 
ing for ammonia by the "Nessler" reagent {vide Index). Troost 
has obtained NHAm 3 Cl. 

Fourth Analytical Reaction. — Pass sulphuretted hydrogen 
through a mercuric solution ; a black precipitate of mercuric 
sulphide (HgS) falls. 

Note. — Sulphuretted hydrogen also precipitates mercurous sul- 
phide (Hg 2 S) from mercurous solutions ; and in appearance the pre- 
cipitates are alike ; hence this reagent does not distinguish between 



MERCURY. 205 

mercurous and mercuric salts. But in the course of systematic 
analysis, mercuric salts are thrown down from solution as sulphide 
after mercurous salts have been otherwise removed. Both sulphides 
are insoluble in sulphydrate of ammonium. 

Note. — An insufficient amount of the gas gives a white or colored 
precipitate of oxysulphide. Prolonged contact with sulphuretted 
hydrogen-water or a sulphydrate, especially when the mixture is 
kept warm, converts the black into a red sulphide. 

JEthiops Mineral, the Hydrargyri Sulphuretum cum Sulphure, is 
a mixture of sulphide of mercury and sulphur, obtained on tritu- 
rating the elements in a mortar till globules are no longer visible. 
Its name is probably in allusion to its similarity in color to the skin 
of the iEthiop. It was formerly official. 

Vermilion or artificial cinnabar, is mercuric sulphide prepared by 
sublimation {Hydrargyri Sulphidum Rubrum, U. S. P.). For a 
description of the Chinese method of manufacturing it see the 
Pharmaceutical Journal for December 17, 1881. 

Teats continued. (The mercury occurring as mercurous salt.) 

Fifth Analytical Reaction. — To a solution of a mercurous 
salt (the mercurous nitrate obtained in the second synthetical 
reaction, for example) add hydrochloric acid or any soluble 
chloride ; a white precipitate of calomel (HgCl) occurs. 

This reaction was formerly official in the Dublin Pharma- 
copoeia as a process for the preparation of calomel. 

Sixth Analytical Reaction. — To solution of a mercurous 
salt add iodide of potassium ; green mercurous iodide (HgT) 
is precipitated. 

Seventh Analytical Reaction. — To a mercurous salt, dissolved 
or undissolved (e. g. calomel), add ammonia ; black salt (e. g. 
chloride) of mercurous ammonium NH. 2 Hg 2 Cl) is formed (see 
previous page). 

Other Tests for Mercury. 

The elimination of mercury in the actual state of metal by 
the copper test, coupled with the production or non-production 
of a white precipitate on the addition of hydrochloric acid to 
the original solution, is usually sufficient evidence of the pres- 
ence of mercury and its existence as a mercurous or mercuric 
salt. But other tests may sometimes be applied with advan- 
tage. Thus, metallic mercury is deposited on placing a drop 
of the solution on a plate of gold (sovereign or half sovereign), 
and touching the drop and the edge of the plate simultaneously 
with a key; an electric current -passes, under these circum- 
stances, from the gold to the key, and thence through the 
liquid to the gold, decomposing the salt, the mercury of which 
forms a white metallic spot on the gold, while the other ele- 



206 THE METALLIC RADICALS. 

ments go on to the iron. This is called the galvanic test, and is 

useful for clinical purposes. Solution of stannous chloride 

(SnCl 2 ) — see Index — from the readiness with which it forms 
stannic salts (SnCl 4 , Sn0 2 , etc.), gives a white precipitate of 
mercurous chloride in mercuric solutions, and quickly still 
further reduces this mercurous chloride (and other mercury- 
salts) to a grayish mass of finely divided mercury ; this is the 
old magpie test, probably so called from the white and gray 
appearance of the precipitate. The reaction may even be ob- 
tained from such insoluble mercury compounds as " white pre- 
cipitate." Confirmatory tests for mercuric and mercurous 

salts will be found in the action of solution of potash, solution 
of soda, lime-water, solution of ammonia, and solution of iodide 

of potassium. ( Vide pages 201 to 205.) Normal alkaline 

carbonates produce yellowish mercurous carbonate and brown- 
ish-red mercuric carbonate, both of them unstable. Al- 
kaline bicarbonates give mercurous carbonate with mercurous 
salts, and with mercuric salts white (becoming red) mercuric 

oxysalt. Yellow chromate of potassium (K 2 Cr0 4 ) gives with 

mercurous salts, a red precipitate of mercurous chromate 

(Hg 2 Cr0 4 ). Mercury and all its compounds are volatile, 

many of them being decomposed, at the same time yielding 
globules of condensed metal : the experiment is most con- 
veniently performed in a test-tube. All dry compounds of 

mercury are decomposed when heated in a dry test-tube with 
dried carbonate of sodium, mercury subliming and condensing 
in visible globules or as a whitish deposit yielding globules 
when rubbed with a glass rod. 

Antidote. — Albumen gives a white precipitate with solution 
of mercuric salts ; hence the importance of administering white 
of egg while waiting for a stomach-pump in cases of poisoning 
by corrosive sublimate. 



QUESTIONS AND EXERCISES. 

293. Name the chief ore of mercury, and describe a process for 
the extraction of the metal. 

294. Give the properties of mercury. 

295. In what state does mercury exist in " Gray Powder " ? 

296. What other preparations of metallic mercury itself are em- 
ployed in medicine? 

297. State the relation of the mercurous to the mercuric com- 
pounds. 

298. Distinguish between an alloy and an amalgam. 

299. State the formulae of the two Iodides of Mercury. 



LEAD. 207 

300. Under what circumstances does mercuric iodide assume two 
different colors? 

301. Illustrate the chemical law of Multiple Proportions as ex- 
plained by the atomic theory, employing for that purpose the stated 
composition of the two iodides of mercury. 

302. Write down the formulae of Mercurous and Mercuric Ni- 
trates and Sulphates. 

303. How is Mercuric Sulphate prepared? 

304. What is the formula of " Turpeth Mineral " ? 

305. Describe the processes necessary for the conversion of mer- 
cury into Calomel and Corrosive Sublimate, using diagrams. 

306. Why is black oxide of manganese sometimes mixed with the 
other ingredients in the preparation of Corrosive Sublimate ? 

307. Give the chemical and physical points of difference between 
Calomel and Corrosive Sublimate. 

308. How may a small quantity of Calomel in Corrosive Subli- 
mate be detected ? 

309. Work out a sum showing how much mercury will be required 
in the manufacture of one ton of Calomel. Arts. 17 cwt. nearly. 

310. Mention official preparations of the chlorides of mercury. 

311. Give the formulae and mode of formation of the Red, Yellow, 
and Black Oxides of Mercury, employing diagrams. 

312. Explain the action of the chief general test for mercury. 

313. How are mercurous and mercuric salts analytically distin- 
guished? 

314. Give a probable view of the constitution of Hydrargyrum 
Ammoniatum, and an equation showing how it is made. 

315. What is the best temporary antidote in cases of poisoning 
by mercury? 



LEAD. 

Symbol Pb. Atomic weight 20G.5. 

Source. — The ores of lead are numerous ; but the one form which 
the metal is chiefly obtained is the sulphide of lead (PbS), or galena 
(from yalrjvr], galene, tranquillity, perhaps from its supposed effect 
in allaying pain). 

Preparation. — The ore is first roasted in a current of air ; much 
sulphur is thus burnt off as sulphurous acid gas, while some of the 
metal is converted into oxide and a portion of the sulphide oxidised 
to sulphate. Oxidization being stopped when the mass presents 
certain appearances, the temperature is raised, and the oxide and 
sulphate, reacting on imdecomposcd sulphide, yield the metal and 
much sulphurous acid gas : — 

2PbO + PbS = Pb, + SO„ 
PbS0 4 + PbS = Pb, + 2S0 2 . 

Uses. — The uses of lead are well known. Alloyed with arsen- 
ieum it forms common shot, with antimony gives type-metal^ with 
tin solder, and in smaller quantities enters into the composition of 



208 THE METALLIC RADICALS. 

Britannia metal, pewter, and other alloys. Lead is so slightly 
attacked by acids that chemical vessels and instruments are often 
made of it. Hot hydrochloric acid only slowly converts it into 
chloride of lead, with evolution of hydrogen. Sulphuric acid by 
aid of air only very slowly attacks it. with formation of sulphate of 
lead and water. Even nitric acid very slowly converts it into 
nitrate, with evolution of nitric oxide and nitrous oxide gases and 
water. 

The salts of lead used in pharmacy and all other preparations 
of lead are obtained, directly or indirectly, from the metal itself. 
Heated in a current of air. lead combines with oxygen and forms 
oxide of lead (PbO) {Plumbi Oxidum, U. S. P.). a yellowish powder 
(massicot), or if fused and solidified a brighter reddish-yellow heavy 
mass of bright scales, termed litharge (from /iftoc. lithos. a stone, and 
up; vpoc. arguros. silver). It is from this oxide that the chief lead 
compounds are obtained. Oxide of lead, by further roasting in a 
current of air, yields reel lead (or minium). Pb 3 4 . or PbO.,:2PbO. 
Both oxides are much used by painters, paper-stainers, and glass- 
manufacturers. White lead is a mixture of carbonate (PbC0 3 ) and 
hydrate of lead (Pb2HO) (commonly 2 molecules of the former to 1 
of the latter), usually ground up with about 7 per cent, of linseed 
oil ; it is made by exposing lead, cast in spirals or little gratings, to 
the action of air. acetic fumes, and carbonic acid, the latter gen- 
erated from decaying vegetable matter, such as spent tan ; oxyace- 
tate of lead slowly but continuously forms, and is as continuously 
decomposed by the carbonic acid, with production of hydrate and 
carbonate, or dry white lead. The grating-like masses, when ground, 
form the heavy white pulverulent official \ Plu mbi Carbonas, U. S. P. 
The latter is the active constituent of Unguentum Plumbi Cetrbonatis, 
U. S. P., the old Unguentum Cerussce. 

Lead compounds are poisonous, producing saturnine colic, or even 
paralysis. These effects are termed saturnine from an old name of 
lead. Saturn. The alchemists called lead Saturn, first, because they 
thought it the oldest of the seven then known metals, and it might 
therefore be compared to Saturn, who was supposed to be the father 
of the gods : and, secondly, because its power of dissolving other 
metals recalled a peculiarity of Saturn, who was said to be in the 
habit of devouring his own children. 

Qua at i valence. — The atom of lead is sometimes quadrivalent 
(V]/'") ; but in most of the compounds used in medicine it exerts 
bivalent activity only (PI/ 7 ). 

PtEACTIONS HAYING (a) SYNTHETICAL AND (Ji) ANALYTICAL 

Interest. 
(a) Synthetical Reactions. 

Acetate of Lead. 
First Synthetical Reaction. — Place a few grains of oxide of 
lead in a test-tube, add about an equal weight of water and 



LEAD. 209 

two and a half times its weight of acetic acid, and boil ; the 
oxide dissolves (or, rather, disappears — dissolves with simul- 
taneous decomposition) and forms a solution of acetate of lead 
(Pb2C 2 H 3 2 ). When cold, or on evaporation if much water 
has been used (the solution being kept faintly acid), crystals 
of acetate of lead (Pb2C 2 H 3 2 ,3H 2 0) are deposited. Larger 
quantities are obtained by the same method. 

PbO + 2HC 2 H 3 2 = Pb2C 2 H,0 2 + H 2 

Oxide of lead. Acetic acid. Acetate of lead. Water. 

This is the official Plumbi Acetas, U. S. P. The salt is termed 
Sugar of Lead, from its sweet taste. Besides its direct use in Phar- 
macy, it forms three-fourths of the Pilula Plumbi cum Opio, B. P. 

Subacetate or Oxyacetate of Lead. 

Second Synthetical Reaction. — Boil acetate of lead with 
about four times its weight of water, and rather more than 
two-thirds its weight of oxide of lead ; the resulting filtered 
liquid is solution of oxyacetate of lead, Liquor Plumbi Sub- 
ucctatis, U. S, P. 

The official Liquor is made by boiling 170 parts of acetate and 
120 of oxide in 800 of distilled water for half an hour (constantly 
stirring), filtering, and making up for- any loss during evaporation 
by diluting the filtrate with boiled and cooled distilled water until 
it weighs 1000 parts. Sp. gr. 1.228. 

A similar solution was used by M. Goulard, who called it Extrac- 
tion Saturni, and drew attention to it in 1770. It is now frequently 
termed Goulard's Extract. A more dilute solution, 3 of Liquor and 
97 of boiled and cooled distilled water, is also official in the Phar- 
macopoeia, under the name of Liquor Plumbi Subacetatis Dilutus. 
The latter is commonly known as Goulard Water or " Lead Water." 
The stronger solution is the chief ingredient in Ceratum Plumbi 
Subacetatis, U. S. P., a slight modification of the old Goulard's 
Cerate. 

Oxi/acetates of Lead. — The official subacetate of load is not a 
definite chemical salt. It is probably a mixture of two subacetates 
of lead, which are well-known crystalline compounds, and which the 
author is disposed to regard as having a constitution similar to that 
he has already indicated for some other salts (see Iron and Antimony, 
also Bismuth). Exposed to air it absorbs carbonic acid gas, and 
hydrato-carbonate of lead is deposited. 

Acetate of Lead (3 molecules) . . Pb s 6C 2 H 3 O a 

tt q i> f Pyro-oxyacetate of lead .... Ph..04(\,ILO., 

UbL - { Goulard's oxyacetate of lead . . . IMaV-V.JU)., 
Oxide of lead (3 molecules) . . . Pb s O s . 



PbO 

Oxide of let 


+ 
id. 


Pb2C a H 8 O a 

Acetate of lead. 


PbJ02C 3 H 3 O s 

Official "sui.acetat 


18* 









210 THE METALLIC RADICALS. 

or 3PbO + 3(Pb2C 2 H 3 2 ) = Pb 3 04C 2 H 3 2 + Pb 3 2 2C 2 H 3 0, 

Oxide of Acetate of Pyro-oxyacetate. Goulard's oxyacetate. 

lead. lead. The official " subacetate. " 

Nitrate of Lead. Red Lead. Peroxide of Lead. 

Third Synthetical Reaction. — Digest a few grains of red lead 
in nitric acid and water ; nitrate of lead (Pb2N0 3 ) is formed, 
and remains in solution, while a puce-colored peroxide of lead 
(PbG 2 ) is precipitated. 

Nitrate of Lead (Plumbi Nitras, IT. S. P.) is more directly made 
by dissolving litharge (PbO) in nitric acid — 

PbO + 2HN0 3 = Pb2N0 3 + H 2 ; 

but the former reaction serves to bring before the reader two other 
oxides of lead, namely, red lead (Pb 3 4 ) and peroxide of lead (Pb0 2 ). 
In the latter oxide the quadrivalent character of lead is obvious. 
Nitrate of lead is used officially in preparing iodide of lead ; for this 
purpose the above mixture is filtered, the precipitate of peroxide of 
lead purified from adhering nitrate by passing hot water through 
the filter, the filtrate and washings evaporated to dryness to remove 
excess of nitric acid, the residual nitrate of lead redissolved by ebul- 
lition with a small quantity of hot water, and the solution set aside 
to crystallize, or a portion at once used for the following experiment. 
Nitrate of lead forms white crystals derived from octahedra. 

Peroxide of lead dissolved in strong hydrochloric acid apparently 
yields an unstable perchloride (PbCl 4 ). 

Iodide of Lead. 

Fourth Synthetical Reaction. — To a neutral solution of ni- 
trate of lead add solution of iodide of potassium ; a precipitate 
of iodide of lead ( Pbl,) falls {Plumbi Todidum, U. S. P.). It 
is soluble in solution of chloride of ammonium. Equal weights 
of the salts may be used in making large quantities. 

Pb2N0 3 + 2KI = Pbl 2 + 2KN0 3 

Nitrate of Iodide of Iodide of Nitrate of 

lead. potassium. lead. potassium. 

Crystal* of Iodide of Lead. — Heat the iodide of lead with 
the supernatant liquid, and if necessary filter ; the salt is dis- 
solved, and again separates in golden crystalline scales as the 
solution cools. 

Oleate of Lead (Lead Plaster). 

Fifth Synthetical Fraction. — Boil together in a small dish 
some very finely-powdered oxide of lead, with nearly twice its 
weight of olive oil, and as much water, well stirrin<>- the mix- 



LEAD. 211 

ture, and from time to time replacing water that has evap- 
orated ; the product is a white mass of oleate of lead 
(Pb2C 18 H 33 2 ), glycerin remaining in solution in the water. 
Larger quantities are prepared in the same manner, but with 
less water. 

3PbO + 3H 2 + 2(C 3 H 5 3C 18 H 33 2 ) = 

Oxide of Water. Oleate of glyceryl 

lead. (olive-oil or oleiue). 

3(Pb2C 18 H 33 2 ) + 2(C,H 5 3HO) 

Oleate of lead Hydrate of glyceryl 

(lead plaster). (glycerin). 

The action between the oxide of lead and olive oil is slow, requir- 
ing several hours for its completion. 

The glycerin may be obtained by treating the aqueous product of 
the above reaction with sulphuretted hydrogen to remove a trace of 
lead, then digesting with animal charcoal, filtering and evaporating. 
But on the large scale glycerin is produced as a by-product in the 
manufacture of candles, for its elements are found in nearly all 
vegetable and animal fats. {Vide Index.) If in making lead plaster 
the mixture be evaporated to dryness {Emplastrum Plumbi, U. S. P.), 
some of the glycerin will escape with the steam and some remain 
with the plaster. 

Modes of forming chloride, sulphide, chr ornate, sulphate, hydrate, 
and other salts of lead are incidentally described in the following 
analytical paragraphs. 

(b) Reactions having Analytical Interest (Tests), 

First Analytical Reaction. — To a solution of lead salt (ace- 
tate, for example) add hydrochloric acid ; a white precipitate 
of chloride of lead (PbCl 2 ) is obtained. Boil the precipitate 
with much water ; it dissolves, but, on the solution cooling, is 
redeposited in small acicular crystals. Filter the cold solution, 
•and pass sulphuretted hydrogen through it; a black precipitate 
(sulphide of lead, PbS) shows that the chloride of lead is sol- 
uble to a slight extent in cold water. 

Note. — A white precipitate on the addition of hydrochloric arid. 
soluble in hot water, and blackened by sulphuretted hydrogen, suf- 
ficiently distinguishes lead salts from those of other metals, but the 
non-production of such a precipitate does not prove the absence of 
a small quantity of lead, chloride of lead being slightly soluble in 
cold water. Hydrochloric acid will be found to be a useful but not 
a delicate test for lead. 

Second Analytical Reaction. — Through a dilute solution of 
a lead salt acidulated with hydrochloric acid pass sulphuretted 
hydrogen ; a black precipitate, of sulphide of lead (PbS) occurs. 

Lead in Water. — The foregoing is a very delicate test. Should a 
trace of lead be present in water used for drinking purposes, sulphur- 



212 THE METALLIC RADICALS. 

etted hydrogen will detect it. On passing the gas through a pint 
of such acidulated water, a brownish color is produced. If the tint 
is scarcely perceptible, set the liquid aside for a day ; the gas will 
become decomposed and a thin layer of sulphur be found at the 
bottom of the vessel, white if no lead be present, but more or less 
brown if it contain sulphide of lead. 

Third Analytical Reaction. — To solution of a lead salt add 
sulphydrate of ammonium ; a black precipitate of sulphide of 
lead falls, insoluble in excess. 

Fourth Analytical Reaction. — To solution of a lead salt add 
solution of chromate of potassium (K 2 Cr0 4 ) ; a yellow precipi- 
tate of chromate of lead (PbCr0 4 ) is formed, insoluble in weak 
acids or in solution of chloride of ammonium. 

Chromes. — This reaction has technical as well as analytical in- 
terest. The precipitate is the common pigment termed chrome yel- 
low or lemon chrome. Boiled with lime and water, a portion of the 
chromic radical is removed as soluble chromate of calcium, and an 
oxychromate of lead, of a bright red or orange color {orange chrome), 
is produced. 

Fifth Analytical Reaction. — To solution of a lead salt add 
dilute sulphuric acid, or a solution of a sulphate ; a white pre- 
cipitate of sulphate of lead (PbS0 4 ) falls. 

Sulphate of lead is slightly soluble in strong acids, and in solu- 
tions of alkaline salts ; it is insoluble in acetic acid. It is readily 
dissolved and indeed decomposed by solution of acetate of ammonium, 
the liquid yielding the ordinary reactions with soluble chromates and 
iodides. 

In dilute solutions the above sulphuric reaction does not take place 
immediately ; the precipitate, however, falls after a time ; its appear- 
ance may be hastened by evaporating the mixture nearly to dryness 
and then rediluting. 

The white precipitate always noticed in the vessels in which diluted, 
sulphuric acid is kept is sulphate of lead, derived from the leaden 
chambers in which the acid is made 5 solubility in strong acid and 
insolubility in weak explains its appearance. 

Antidotes. — From the insolubility of sulphate of lead in water, the 
best antidote, in a case of poisoning by the acetate or other soluble 
salt of lead, is a soluble sulphate, such as Epsom salt, sulphate of 
sodium or alum, vomiting being also induced, or the stomach-pump 
applied as quickly as possible. 

Other tests for lead will be found in the reaction with iodide 
of potassium (vide p. 209); with alkaline carbonates, a white 
precipitate (2PbC0 3 -f Pb2HO) insoluble in excess; with 
alkalies, a white precipitate (Pb2HO) more or less soluble in 
excess; with alkaline phosphates, arseniates, ferrocy amides, and 
cyanides, precipitates mostly insoluble, but of no special analy- 



LEAD. 213 

tical interest. Insoluble salts of lead are decomposed by solu- 
tions of potash (KHO) or soda (NaHO). 

The metal is precipitated in a beautifully crystalline state by 
metallic zinc and some other metals ; the lead tree is thus 
formed. The blowpipe-flame decomposes solid lead com- 
pounds placed in a small cavity in a piece of charcoal, a soft 
malleable bead of metal being produced, and a yellowish ring 
of oxide deposited on the charcoal. 



QUESTIONS AND EXERCISES. 

316. Write down equations descriptive of the smelting of galena. 

317. Mention some of the alloys of lead. 

318. How is litharge produced? 

319. Give the formulae of white lead and red lead. 

320. Describe the manufacture of white lead. 

321. What is the quantivalence of lead? 

322. Draw a diagram expressive of the formation of ordinary Ace- 
tate of Lead. 

323. Describe the preparation and composition of Liquor Plumbi 
Subacetatis. 

324. What is the action of nitric acid on red lead, litharge, and 
metallic lead? 

325. How is the official Iodide of Lead prepared ? 

326. Describe the reaction between oxide of lead, water, and olive 
oil, at the temperature of boiling water, and give chemical formulae 
explanatory of the constitution of the products. 

327. Mention the chief tests for lead. 

328. How would you search for lead in potable water? 

329. What is the composition of chrome yellow? 

330. State a method whereby lead, barium, and silver may be 
separated from each other. 

331. Name the best antidote in case of poisoning by the soluble 
salts of lead. 



SILVER. 

Symbol Ag. Atomic weight 107.7. 

Source. — This element occurs in nature in the metallic state and 
as ore, the common variety of the latter being sulphide of silver 
(Ag 2 S) in combination with much sulphide of lead, forming ar- 
gentiferous galena. 

Preparation. — The lead from such galena (p. 207) is melted and 
slowly cooled; crystals of lead separate and are raked out from the 
still fluid mass, and thus an alloy very rich in silver is finally ob- 
tained : this is roasted in a current of air, whereby the lead is oxi- 
dized and removed as lithrage, pure silver remaining. Other ores un- 
dergo various preparatory treatments according to their nature, and 



214 THE METALLIC RADICALS. 

are then shaken with mercury, -which amalgamates with and dissolves 
the particles of metallic silver, the mercury being subsequently re- 
moved from the amalgam by distillation. Soils and minerals con- 
taining metallic silver are also treated in this way. An important 
improvement in the amalgamation process, by which the mercury 
more readily unites with the silver, consists in the addition of a 
small proportion of sodium to the mercury — a discovery simul- 
taneously made in England by Crookes, and in New York by Wurtz. 
Silver is not readily affected by the weak acids or other fluids of 
food, though it is rapidly tarnished by sulphur or sulphur com- 
pounds. It does not perceptibly attack hydrochloric acid ; reduces 
strong nitric acid to nitrous anhydride (N 2 3 ), and a weaker acid to 
nitric oxide (NO) ; it reduces hot sulphuric acid to sulphurous anhy- 
dride (SO.,), sulphate of silver (Ag 2 S0 4 ) being formed. The latter 
salt is crystalline and slightly soluble in water. 

Reactions having (a) Synthetical and (A) Analytical 
Interest. 

(a) Synthetical Reaction. 
Impure Nitrate of Silver. 

First Synthetical Reaction. — Dissolve a silver coin in nitric 
acid ; nitric oxide gas (NO) and nitrous anhydride (N 2 3 ) are 
evolved, and a solution of nitrates of silver and copper is ob- 
tained. 

Silver Coinage. — Pure silver is too soft for use as coin ; it is there- 
fore hardened by alloying with copper. The silver money of Eng- 
land contains 7.5, of Prussia 25, and of France 10 and 16.5 percent, 
of copper ; for the fineness of the French standard silver is 0.900 in 
the five-franc piece, while an inferior alloy of 0.835 is used for the 
lower denominations. The single-franc piece, composed of the latter 
alloy, is still made to weigh five grammes, the weight originally 
chosen for the franc as the unit of the monetary scale when the fine- 
ness of the coin was 0.900. It has now become a token, like the 
British shilling, of which the nominal value exceeds the metallic 
value. One pound troy of British standard silver is coined into 66 
shillings, of which the metal is worth from 60s. to 62s., or less or more 
according to the market price of silver. The standard fineness of 
this silver is 0.925, three alloy in 40. British silver coins are a 
legal tender in payments to the amount of 40s. only. 

Chloride of Silver. 

Second Synthetical Reaction. — To the product of the forego- 
ing reaction add water and hydrochloric acid or a soluble chlo- 
ride ; white chloride of silver (AgCl) is precipitated, copper still 
remaining in solution. Collect the precipitate on a filter, and 
wash with water ; it is pure chloride of silver. 

Note. — The nitrates of silver and copper may also be separated by 
evaporating the solution of the metals in nitric acid to dryness, and 



SILVER. 215 

gently heating the residue, when the nitrate of copper is decom- 
posed, but the nitrate of silver is unaffected. The latter may be dis- 
solved from the residual oxide of copper by water. 

Chloride of silver may be obtained in crystals by evaporation 
of its solution in ammonia. 

Pure Silver. 

Third Synthetical Reaction. — Place the chloride of silver of 
the previous reaction in a dish, wet it with dilute sulphuric 
acid, and float a piece of sheet zinc on the mixture ; metallic 
silver is precipitated, and after about one day wholly removed 
from solution. Collect the precipitate on a filter and wash with 
water ; it is pure metallic silver, and is readily fusible into a 
single button. 

Note. — Any considerable quantity of chloride of silver may also 
be reduced to the metallic state by fusion, in a crucible, with about 
half its weight of carbonate of sodium. 

Pure Nitrate of Silver. 

Fourth Synthetical Reaction. — Dissolve the pure silver of the 
previous reaction in nitric acid (3 of silver require about 2 or 
2 £ of strong acid diluted with 5 of water), and remove excess 
of acid by evaporating the solution to dryness, slightly heating 
the residue ; the product is pure nitrate of silver. Dissolve by 
heating with a small quantity of water ; on the solution cooling, 
or on evaporation, colorless tabular crystals of nitrate of silver 
are obtained. 

3Ag 2 + 8HN0 3 = 2NO -f 6AgN0 3 + 4H„0 

Silver. Nitric acid. Nitric oxide. Nitrate of silver. Water. 

Notes. — The solution of pure or refined silver {Argentum Purifi- 
catuni, B. P.) in nitric acid, evaporation, and crystallization consti- 
tutes the usual process for the preparation of the nitrate {Argenti 
Nitras, U. S. P.). The salt fused with 4 per cent, of hydrochloric 
acid (yielding about 5 per cent, of interlacing chloride of silver), 
and poured into proper moulds, yields the white cylindrical sticks 
or rods {Argenti Nitras Fusus, U. S. P.) commonly termed caustic 
(from tcaio, kaio, I burn), or lunar caustic. (The alchemists called 
silver Diana or Lima, from its supposed mysterious connection with 
the moon.) These " caustic points" commonly contain nitrate of 
potassium, which imparts toughness, the Argenti Nitras Dilutus, 
U. S. P., being formed of equal weights of the salts (toughened 
Nitrate of Silver, or Toughened Caustic, Nitrate of Silver ami Po- 
tassium, Argenti et Potassii Nitras, B. P., or Mitigated Caustic). 
The specimen of nitrate of silver obtained in the above reaction, 
dissolved in water, will be found useful as an analytical reagent. 
Nitrate of silver is soluble in rectified spirit, but after a time re- 
action and decomposition occur. 

Silver salts are decomposed when in contact with organic matter. 



216 THE METALLIC RADICALS. 

especially in the presence of light or heat, the metal itself being lib- 
erated, or a black insoluble compound formed. Hence the value of 
the nitrate in the manufacture of indelible ink for marking linen •, 
hence, too, the reason of the practice of rendering silver solutions 
clear by subsidence and decantation, rather than by nitration through 
paper ; and hence the cause of those cases of actual combustion 
which have been known to occur in preparing pills containing oxide 
of silver and essential oil or other organic matter. Linen marked 
with such ink should not be cleansed by aid of bleaching-liquor, as 
the marked parts are then apt to be rapidly oxidized into perfectly 
rotten matter, holes resulting. Paul says the reaction is as follows : 
Ag 2 + CaCl 2 2 = 2AgCl -f- CaO + 2 . 

Oxide of Silver. 

Fifth Synthetical Reaction. — To a few drops of solution of 
nitrate of silver add solution of potash or soda or lime-water*, 
an olive-brown precipitate of oxide of silver (Ag 2 0) occurs. 
The washed and dried oxide, like most silver compounds, is 
decomposed by heat, with production of metal. It is also 
readily reduced when triturated with oxidizable or combusti- 
ble substances. (See the previous paragraph). 

The Argeati Oxidum, U. S. P., may be thus made : — 
2AgN0 3 + Ca2HO = Ag 2 + Ca2N0 3 + H 2 

titrate of Hydrate of Oxide of Nitrate of Water, 

silver. calcium. silver. calcium. 

Oxide of silver is also precipitated on adding ammonia to a solu- 
tion of nitrate of silver, but it rapidly is taken up by the nitrate of 
ammonium formed at the same time, nitrate of argentammonium, 
NH 3 AgN0 3 being, doubtless, produced. More ammonia then yields 
nitrate of argent-ammon-ammonium (see p. 204). The direct solu- 
tion of oxide of silver in ammonia may give the highly explosive 
substance known as Berthollet's fulminating silver (?NII 2 Ag). Or- 
dinary fulminating silver, C 2 N 2 2 Ag 2 , results from the interaction 
of nitrate of silver, nitric acid, and alcohol. The corresponding 
mercury compound, C 2 N 2 0.,Hg, is used in percussion-caps. 

Methods of forming several other salts of silver are incidentally 
mentioned in the following analytical paragraphs. 

(Z/) Reactions having Analytical Interest (Tests'). 

First Analytical Reaction. — To a solution of a silver salt 
add hydrochloric acid or other soluble chloride ; a white curdy 
precipitate of chloride of silver falls. Add nitric acid, and 
boil ; the precipitate does not dissolve. Pour off the acid and 
add solution of ammonia ; the precipitate dissolves. Neutralize 
the ammoniacal solution by an acid; the chloride of silver is 
reprecipitated. 



SILVER. 217 

This is the most characteristic test for silver. The precipitated 
chloride is also soluble in solutions of hyposulphite of sodium or 
cyanide of potassium — facts of considerable importance in photo- 
graphic operations. 

Other analytical reagents than the above are occasionally 
useful. Sulphuretted hydrogen, or sulphydrate of ammo- 
nium, gives a black precipitate, sulphide of silver (Ag 2 S), in- 
soluble in alkalies. Solutions of potash or soda give a brown 

precipitate, oxide of silver (Ag 2 0), converted into a fulmina- 
ting compound by prolonged contact with ammonia. Phos- 
phate of sodium gives a pale yellow precipitate, phosphate of 

silver (Ag 3 P0 4 ), soluble in nitric acid and in ammonia. 

Arseniate of ammonium gives a chocolate-colored precipitate, 
arseniate of silver (AggAsO*), already noticed in connection 

with arsenic acid. Iodide or bromide of potassium gives a 

yellowish-white precipitate, iodide (Argenti Iodidum, U. S. P.) 
or bromide of silver (Agl or AgBr), insoluble in acids and only 

slightly soluble in ammonia. -Cyanide of potassium gives 

a white precipitate, cyanide of silver ( AgCy), soluble in excess, 
sparingly soluble in ammonia, insoluble in dilute nitric acid, 
soluble in boiling concentrated nitric acid. Argenti Cyanidum, 
U. S. P., may be made by distilling a mixture of ferrocyanide 
of potassium and diluted sulphuric acid, and passing the re- 
sulting hydrocyanic acid into a solution of nitrate of silver : 
HCy -KAgN0 3 = AgCy + HN0 3 (the precipitate is well 

washed and dried). Yellow chromate of potassium (K. 2 CrO + ) 

gives a red precipitate, chromate of silver (Ag 2 Cr0 4 ). Red 

chromate of potassium also gives a red precipitate, acid chro- 
mate of silver (Ag,Cr0 4 ,Cr0 3 ). Many organic acids afford 

insoluble salts of silver. Several metals displace silver from 

solution, mercury forming in this way a crystalline compound 
known as the silver tree, or Arbor Diamx. In the blowpipe- 
flame, silver salts, placed on charcoal with a little carbonate of 
sodium, yield bright globules of metal accompanied by no in- 
crustation as in the corresponding reaction with lead salts ; the 
experiment may be performed with the nitrate, which first 
melts, and then, like all nitrates, deflagrates, yielding a white 
metallic coating of silver which slowly aggregates to a button. 

Antidotes. — Solution of common salt, sal-ammoniac, or any other 
inert chloride should obviously be administered whore large doses of 
nitrate of silver have been swallowed. A quantity of sea-water or 
brine would convert the silver into insoluble chloride, and at the 
same time produce vomiting. 



218 THE METALLIC RADICALS. 

QUESTIONS AND EXERCISES. 

332. By what process is silver obtained from argentiferous ga- 
lena? 

333. What weight of English silver coin will yield one pound of 
pure nitrate of silver ? 

334. How may the metal be recovered from an impure mixture of 
silver salts? 

335. Give a diagram showing the formation of nitrate of silver 
from the metal. 

336. Describe the reaction of lime-water and nitrate of silver. 

337. Mention the chief test for silver, and the precautions to be 
observed in order that silver salts may be distinguished from those 
of lead and mercury. 

338. Name the antidote for silver. 



directions for applying some of the foregoing reac- 
tions to the analysis of an aqueous solution of 
salts of one of the metals, copper, mercury 
(either as mercurous or mercuric salt), lead, 
Silver. 

Add hydrochloric acid : — 

Silver is indicated by a white curdy precipitate, soluble in 

ammonia. 
Mercurous salts also by a white precipitate, turned black 

by ammonia. 
Lead by a white precipitate, insoluble in ammonia. Con- 
firm by boiling another portion of the hydrochloric 
precipitate in water : it dissolves. 
If hydrochloric acid gives no precipitate, silver and mercu- 
rous salts are absent. Lead can only be present in very small 
quantity. Mercuric salts may be present. Copper may be 
present. Divide the liquid into three portions, and apply a 
direct test for each metal as follows : — 

Lead is best delected by the sulphuric test ; the tube 
being set aside for a time if the precipitate does not 
appear at once. 
Mercury is best detected by the copper test. If present, 

here it occurs as mercuric salt. 
Copper betrays itself by the blue color of the liquid under 
examination. Confirm by the ammonia test. 
If the above reactions are not thoroughly conclusive, con- 
firmatory evidence should be obtained by the application of 
some of the other reagents for copper, mercury, lead, or silver. 



ANALYTICAL CHARTS. 



219 



Note I. — If HCl gave no precipi- 
tate, neither Hg(ous) nor Ag is 
present; and Pb onlvin minute 
amount, if at all. 

Note II. — Hg obtained here 
must have existed in the solu- 
tion as a mercurous salt. 

Note III.— Sb is also precipi- 
tated by HCl, but is dissolved 
on adding more HCl ; the Hg, 
Pb, and Ag precipitates are not 
soluble in excess of HCl. 


> 

X 


Ppt. 

Hg(ous) Pb Ag. 

AddNHJIO. 

Hg(ous), black ppt. 

Pb, ppt. still white. 


As, yellow ppt. 
Sb, orange ppt. 
Cu ) 

Hg(ic) > black ppt. 
Pb J 

Test original solution for 
CubyNH 4 HO; blue sol. 
Hg by Cu ; globules. 
Pb by H 2 S0 4 ; white ppt. 

Note I.— If HoS gave no precipi- 
tate, neither Cu, Hg, Pb, As, nor 
Sb is present. 

Note II.— Hg and Pb may give 
colored precipitates (ox y sul- 
phides, etc.) with H 2 S if too little 
of the latter has been passed 
through the solution. 


o 

a 

a 

5" 

C F* 


9 

P 
CD 

O 

6 
°. 

JD 

CD 

CD 

E 

CO* 

5' 

CD 

eta 

c 


Ppt. 

Fe Al Zn 

Fe, black ppt. 

Test original solution for 

ferric salt by K 4 Fcy {dark 

blue ppt.) ; and for ferrous 

salt by K 6 Fdcy {dark blue 

Zn } white PP 1 - 

Test original solution by 
NH 4 HO. J 

Al, white ppt. insoluble 
in excess. 

Zn, white ppt. soluble in 
excess. 


If H 2 S gave no precipitate, the metal is still in the liquid; 
add XH 4 C1, XHJIO, and NH 4 HS. 


W o x 2 * ^ ca G'- K 



£L w 



> 

> 

la 

§§ 

la 



220 



THE METALLIC RADICALS. 



— 05 

fc fc 

< <{ 

fc O - 

§ ° 
Cms 

fe J U 

' 3 « 



fe 



QD 



a <j u 

fe a ^ 

C s2 K 

O H 

fe a 

o o £ 



z — ^ a 

JH fe H S 

J J s 3 



Filtrate 

Cu Hg(ic) Pb As Sb Fe Al Zn Ba Ca Mg K Na NH 4 . 

Pass H 2 S through the liquid until it ceases to cause any alteration ; filter. 


fc 


§1 

fc 53 

o 5 


fc « 

sfc < H 




, ^ . 

4 |a"2 2-=r 

gfc "rfc^eS -^ 


2 




^J? -9;iqAv 


.S-© 

Id I** 

s-° .1 c 2 

fe icf 


r w ^fcoa 
ft $ 

'0 s 

i* "3 


Precipitate 

Fe Al Zn. 
Wash, dissolve in HCl, boil (with 
a few drojts of llNOj if neces- 
sary) ; add KHO, stir, filter. 


I §§1 

Sjjgfc^ 

fcl 


1 -ais $ 
fe g*§. 


_a, ©_£, . 

SN.glJ 

fe ^ ft 


-2 § .r.o&^d 

1-1 e- "■ a 


Precipitate 

Cu Hg(ic) Pb As Sb. 

Wash, digest in NH 4 IIS, filter. 


Filtrate 

As Sb. 

Add HC2H3O2 

and boil ; "digest 

1 lie precipitate 

in stronffliCl; 

boil, dilute, 

filter. 


U3 OQ ^ . , 

2 _£ a 2 -3 J "3 5 

fe 2 c ~- .^ « 


g«j £ 5 o'^g 


Sna &~~ ~^ "^2 fe? 


+> "ee 

'.zr~~ 5 

fe O. S3 
c3 


g^« 




2 o 

. T — 

„ai A * J 


1 


fe « ft 


•r-T ~ 'ft jj 



ANALYTICAL CHARTS. 



221 



Table of short directions for applying some of the 
foregoing reactions to the analysis of an aqueous 
solution of salts of any or all of the metals, 
Copper, Mercury (either mercurous or mercuric 
salt, or both), lead, sllver. 

Add hydrochloric acid, filter, and wash the precipitate with a 
small quantity of cold water. 



Ppt. 

Pb Hg(ous) Ag. 
Wash with boiling water. 


Filtrate. 

Cu Hg(ic) Pb. 

Divide into three portions. 

Test for 


Ppt. 

Hg(ous) Ag. 
AddNH 4 HOl 


Filtrate. 

Pb. 

Add H 2 S0 4 , 

white ppt.* 


Cu byNH 4 HO ; blue sol. 

Hg (mercuric) by Cu 5 

globules. 

Pb by H 2 S0 4 ; white ppt* 


Precipitate 

Hg 

(mercurous) 

— black. 


Filtrate. 

Ag. 

Add HN0 3 

white ppt. 





OUTLINE OF THE PRECEDING TABLES. 



HC1 


H 2 S 


NH 4 HS 


(NH 4 ) 2 C0 3 


(NH 4 ) 2 HAs0 4 




Hg. 


Cu 


Zn 


Ba 


Mg 


K 


(as mercurous 


1 












salt) 


Hg 


'Z'^ 2 


Al 


Ca 




Na 


Pb 

(partially) 


(as mer- 
curic salt) 

Pb 
(entirely) 




Fe 






NH 4 


Ag 
















* Liquids containing only a small quantity of lead do not readily 
yield sulphate of lead on the addition of sulphuric acid. Before lead 
can be said to be absent, therefore, the liquid should be evaporated 
to dryness with one drop of sulphuric acid, and the residue digested 
in water; any sulphate of lead then remains as a heavy white in- 
soluble powder. 



222 THE METALLIC RADICALS. 

The practical student should examine solutions containing the 
common metals until he is able to analyze with facility and accuracy. 
In this way he will best perceive the peculiarities of each element 
and their general relations to each other. As the rarer metals are 
not included here, the tables are not complete analytical schemes ; 
only general memoranda respecting them will therefore now be given. 



Memoranda relating to the General Analytical 
Table (page 220). 

The group-tests adopted in the Table are, obviously, hydro- 
chloric acid, sulphuretted hydrogen, sulpliydrate of ammonium, 
carbonate of ammonium, and arscniate of ammonium. If a 
group-test produces no precipitate, it is self-evident that there 
can be no member of the group present. At first, therefore, 
add only a small quantity of a group-test, and if it produces no 
effect add no more ; for it is not advisable to overload a solu- 
tion with useless reagents ; substances expected to come down 
as precipitates are not unfrequently held in the liquid by excess 
of acid, alkali, or strong aqueous solution of some group- 
reagent, thoughtlessly added. Indeed, experienced manipulators 
not unfrequently make preliminary trials with group-reagents 
on a few drops only of the liquid under examination ; if a pre- 
cipitate is produced, it is added to the bulk of the original liquid 
and the addition of the group-reagent continued ; if a precipi- 
tate is not produced, the few drops are thrown away, and the 
unnecessary addition of a group-reagent thus avoided alto- 
gether, an advantage fully making up for the extra trouble of 
making a preliminary trial. While shunning excess, how- 
ever, care must be taken to avoid deficiency ; a substance only 
partially removed from solution through the addition of an in- 
sufficient amount of a reagent will appear where not expected, 
be consequently mistaken for something else, and cause much 
trouble ; this will not occur if the appearance, odor, or reaction 
of the liquid on test-paper be duly observed. It is also a good 
plan, when a group-reagent has produced a precipitate and the 
latter has been filtered out, to add a little more of the reagent 
to the clear filtrate ; if more precipitate is produced, an insuf- 
ficient amount of the group-test was introduced in the first in- 
stance ; but the error is corrected by simply refiltering ; if no 
precipitate occurs, the mind is satisfied and the way cleared 
for further operations. 

Group-precipitates, or any precipitates still requiring exami- 
nation, should, as a rule, be well washed before further testing ; 
this is to remove the aqueous solution of other substances ad- 



ANALYTICAL MEMORANDA. 223 

hering to the precipitate (the mother liquor, as it is termed), so 
that subsequent reaction may take place fairly between the re- 
agent used and the precipitate only. A precipitate is some- 
times in so fine a state of division as to retard filtration by 
clogging the pores of the paper, or even to pass through the 
filter altogether ; in these cases the mixture may be warmed 
or boiled (or a fresh quantity of the original solution may be 
warmed before the group-test is added), which usually causes 
aggregation of the particles of a precipitate, and hence facili- 
tates the passage of liquids. 

Division of Work. — It is immaterial whether a solution be 
first divided into group-precipitates or each precipitate be ex- 
amined as soon as produced ; if the former method be adopted, 
confusion will be avoided by labelling or marking the funnels 
or papers holding the precipitate, " the HC1 ppt.," " the H. 2 S 
ppt.," and so on. 

The colors and general appearance of the various sulphides 
and hydrates precipitated should be borne in mind, as the ab- 
sence of other bodies, as well as the presence of those thrown 
down, is often at once thus indicated. 

Application of con firm atari/ tests must be frequent. 

Results of analysis should be recorded neatly in a memo- 
randum-book. 

The various reactions which occur in an analysis have al- 
ready come before the reader in going through the tests for 
the individual metals or in other analytical operations ; it is 
unnecessary, therefore, again to draw out equations or dia- 
grams. But the reactions should be thought over, and if not 
perfectly clear to the mind, be written out again and again till 
thoroughly understood. 



QUESTIONS AND EXERCISES. 

339. Give processes for the qualitative analysis of liquids contain- 
ing the following substances: — a. Antimony and Mercurous salt; 
b. Lead and Calcium ; c. Silver and Mercurous salt; <!. Lead and 
Mercuric salt ; e. Copper and Arsenicum;/. Arsenicum and Anti- 
mony; g. Aluminium and Zinc; h. Iron and Copper; /'. Magne- 
sium, Calcium, and Potassium;,/'. Silver, Antimony. Zinc. Barium, 
and Ammonium. 

340. Enumerate the so-called group-tests. 

341. Give a general sketch o\' the method of analyzing a solution 
suspected to contain two or more salts of common metals. 

342. Classify the common metals according to I heir analytical 
relations. 



224 RARER METALLIC RADICALS. 

METALS OF MINOR PHARMACEUTICAL 
IMPORTANCE. 

Thus far has been considered, somewhat in detail, the chemistry 
of the common metals, salts of Avhich are frequently used in medicine 
or in testing medical substances. These are — 

Potassium, Barium, Zinc, Arsenicum, Mercury, 

Sodium, Calcium, Aluminium, Antimony, Lead, 

Ammonium (?), Magnesium, Iron. Copper, Silver. 

Of the remaining metals, eight have considerable interest for the 
student of medicine or of pharmacy, namely : — 

Lithium, Manganese, Tin, Platinum, Bismuth. 

Cerium, Chromium, Gold, 

Compounds of four more occasionally come under notice : — 

Strontium, Cobalt, Nickel, Cadmium. 

These twelve metals of minor pharmaceutical interest may be 
shortly studied, a few only of the reactions of each (just those men- 
tioned in the following pages) being performed. When all have 
been thus treated, their respective positions in the analytical groups 
will be indicated, and a tabular scheme by which an analysis of a 
solution containing any metal may be effected. Thus, step by step, 
we may learn how to analyze -almost any substance that may occur, 
and know to what extent the presence of a rarer will interfere with 
the ordinary tests for a common element ; additional illustrations of 
the working of chemical laws will be acquired, and the store of 
chemical and pharmaceutical facts increased. The opportunity thus 
afforded for improvement in habits of neatness in manipulation, pre- 
cision, and classification furnishes another and no mean reason why 
such experiments should be prosecuted, the direct value of which 
may not be considerable to medical and pharmaceutical learners. 

LITHIUM. 

Symbol L. Atomic weight 7. 

Lithium is widely distributed in nature, but usually in minute 
proportions compared with other elements. A trace of it may be 
found in most soils and waters, a Cornish spring containing con- 
siderable quantities as chloride. 

One salt used in medicine is the Citrate (L 3 C 6 II 5 0.) (Lithii Citras, 
U. S. P.), occurring in white deliquescent crystals or powder, pre- 
pared by dissolving 50 grains of the Carbonate (L 2 C0 3 ) and 95 of 
citric acid (50 to 95 if both are quite pure) in 1 ounce of water, 
evaporating to a low bulk, and setting aside in a dry place to crys- 
tallize, or at once evaporating to dryness and powdering the residue. 
The crystals have the formula L 3 C 6 H 5 7 ,4H 2 ; dried at 212° F., 
L 3 C 6 H 5 7 ,II 2 (Umney). 

3L 2 C0 8 + 2H 3 C fi H 5 7 = 2L,C 6 H 5 7 + 3H 2 + 3C0 2 

Carbonate Citric acid. Citrate of Water. Carbonic 

of lithium. lithium. acid gas. 



LITHIUM. 225 

The benzoate {Litliii Benzoas, , LC 7 H 5 2 , U. S. P.), bromide 
(Liihii Bromidum, LBr, U. S. P.), and salicylate (Lithii Sa- 
lici/las, 2LC 7 H 5 3 ,H 2 0, U. S. P.) may be similarly prepared 
from the respective acids. 

The above-named lithium salts are officially tested as follows, the 
Bromide being acted upon directly without ignition : — 

" On dissolving the residue, left on ignition [of either salt] in 
diluted hydrochloric acid, and evaporating the filtered solution to 
dryness, 1 part of the residue should be completely soluble in 3 
parts of absolute alcohol, which, when ignited, should burn with a 
crimson flame, and the addition of an equal volume of stronger 
ether to the alcoholic solution should produce no precipitate (salts 
of alkalies). On dissolving another portion of the residue in a 
small quantity of water, the solution should produce no precipitate 
with test-solution of oxalate of ammonium (salts of alkaline earths). 
The aqueous solution should remain unaffected by hydrosulphuric 
acid or sulphide of ammonium (abs. of metals)." — U. S. P. 

The carbonate {Lithii Carbonas, TJ. S. P.) is a white granular 
powder obtained from the minerals which contain lithium ; namely, 
lepidolite (from Isirlc, lepis, a scale, and lidos, lithos, a stone ; it has 
a scaly appearance), triphane (from rpelc, treis, three, and tyalvu, 
phaino, I shine), or spodumene (from oirodou, spodoo, I reduce to 
ashes, in allusion to its exfoliation in the blowpipe-flame), and 
petalite (from Treralov, petalon, a leaf 5 its character is leafy and 
laminated). Each contains silicate of aluminium, with fluoride of 
potassium and lithium in the case of Austrian lepidolite, which is 
the most abundant source, and silicate of sodium and lithium in the 
others. The lepidolite is decomposed by sulphuric acid ; alumina, 
etc., precipitated by ammonia ; the filtrate evaporated and the residue 
ignited; the resulting sulphates dissolved in water and the lithium 
precipitated by a carbonate. The preparation of alum is sometimes 
made a part of the process, and other obvious modifications may be 
introduced. Liquor Lithice Effervescens, B. P., is a solution of 10 
grains of carbonate of lithium in 1 pint of water charged with 5 
times its volume of carbonic acid gas and kept in ordinary aerated- 
water bottles. " Half a pint, evaporated to dryness, yields 5 grains 
of a white solid residue, answering to the tests for carbonate of 
lithium. . . . Ten grains of the latter salt neutralized with sul- 
phuric acid, and afterwards heated to redness, leave 14.80 grains 
of dry sulphate of lithium, which, when redissolved in distilled 
"water, yields no precipitate with oxalate of ammonium or solution 
of lime," indicating absence of salts of calcium and aluminium. 
Citrate of lithium should yield by incineration 52.8 per cent, ol' 
white carbonate of lithium. According to C. N. Draper, carbonate 
of lithium is soluble in OS parts of water at 15° C, and 131 at 100°. 

Urate of lithium* is more soluble than urate of sodium: hence 



* Urates will be considered subsequently in connection with 
acid. 



226 RARER METALLIC RADICALS. 

lithium preparations are administered to gouty patients in the hope 
that urate of sodium, with which such systems are loaded, may be 
converted into urate of lithium and removed. 

Li chemical position lithium stands between the alkaline and the 
alkaline-earth metals, its hydrate, carbonate, and phosphate being 
slightly soluble in water. The double chloride of platinum and 
lithium also is soluble in water. Its atom is univalent, I/. 

Analytical Reaction. — Moisten the end of a platinum wire 
with solution of a minute particle of solid lithium salt, and in- 
troduce it into the flame of a Bunsen burner or other slightly 
colored flame (spirit-lamp or blowpipe-flame) ; a magnificent 
crimson tinge is imparted. 

The light thus emitted by ignited lithium vapor is of a purer 
scarlet than that given by strontium, the next element. AVhen the 
flames are examined by spectral analysis (physically analyzed by a 
prism), the red rays are, in the case of strontium, found to be asso- 
ciated with blue and yellow, neither of which is present in the 
lithium light, blue lithium rays only appearing at temperatures 
much higher than those of ordinary air-gas flames. 

STRONTIUM. 

Symbol Sr. Atomic weight 87.4. 

Source. — Strontium is not widely distributed in nature, but the 
carbonate (SrC0 3 ) known as strontianite, and the sulphate (SrS0 4 ), 
known as celestine (from caelum, the sky, in allusion to its occasional 
bluish color), are by no means rare minerals. 

Salts of strontium are not employed in medicine. They are 
chiefly used by firework-manufacturers in preparing red fire. The 
color they impart to flame is a beautiful crimson — ignited strontium 
vapor emitting red rays, as already explained. Nitrate of strontium 
(Sr2N0 3 ) is best for pyrotechnic compositions, its oxygen enabling 
it to burn freely when mixed with charcoal, sulphur, etc. It, or any 
salts, may be obtained by dissolving the carbonate in the appropri- 
ate acid, or by igniting the cheaper sulphate with coal, whereby 
sulphide (SrS) is produced, and dissolving this in acid. 

The position of strontium among the chemical elements is between 
barium and calcium ; its sulphate is very sparingly soluble in water. 
Its atom, like those of barium and calcium, is bivalent (Sr"). 
Analytical Reactions ( Tests). 

First Analytical Reaction. — To a solution of a strontium 
salt (Sr2N0 3 or SrCl 2 ) add carbonate of ammonium ; a white 
precipitate of carbonate of strontium (SrC0 3 ) falls. 

Second Analytical Reaction. — To a solution of a strontium 
salt add sulphuric acid previously so diluted that it will not 
precipitate calcium salts, or add an equally dilute solution of 
any sulphate (c. g., that of calcium itself) ; a white precipitate 
of sulphate of strontium (SrS0 4 ) falls, The formation of this 



STRONTIUM. 227 

precipitate is promoted by stirring and setting the liquid aside 
for some time. 

Barium is precipitated immediately under similar circumstances. 
Third Analytical Reaction. — To a dilute solution of a stron- 
tium salt add yellow chromate of potassium ; no precipitate 
falls. 

Barium may be separated from strontium by chromate of potas- 
sium, that reagent at once precipitating barium from aqueous or 
acetic solutions. The value of the reaction is enhanced if the solu- 
tions be dilute and if acetic acid or acetate of ammonium be pres- 
ent, chromate of strontium being far more soluble in such fluids 
than in water (Ransom). It is also more soluble in cold than in 
hot fluids. 

Fourth Analytical Reaction. — Insert a fragment of a stron- 
tium salt in the blowpipe-flame, or other equally colorless flame, 
or hold the end of a platinum wire dipped into a strontium so- 
lution in the flame ; a crimson color is imparted. 

Other Analytical Reactions. — Alkali-metal phosphates, ar- 
senates, and oxalates give white insoluble precipitates with 

strontium as with barium and calcium. Strontium, like 

calcium, but unlike barium, is not precipitated by hydrofluo- 
silicic acid. 

Cerium. Ce. At. wt. 138. — This element occurs in the mineral 
cerite (a-silicate of iron, calcium, and the three rare metals, cerium, 
lanthanum, and didymium) ; also occasionally as impure fluoride, 
carbonate, and phosphate. The oxalate of cerium, a white granular 
powder, is the only official salt ; it may be obtained from cerite by 
boiling the powdered mineral in strong hydrochloric acid for several 
hours, evaporating, diluting, and filtering to separate silica; adding 
ammonia to precipitate hydrates of all the metals except calcium ; 
filtering off, washing, redissolving in hydrochloric acid, and adding 
oxalic acid to precipitate oxalate of cerium. The preparation will 
still contain oxalates of lanthanum and didymium 5 it is therefore 
strongly calcined, the resulting oxides of lanthanum and didymium 
dissolved out to some extent by boiling with a concentrated solution 
of chloride of ammonium, the residual oxide of cerium dissolved in 
boiling hydrochloric acid, and oxalate of ammonium added to pre- 
cipitate white, granular oxalate of cerium (Ce 2 /// 3C 2 4 ,9H 2 0), Ac- 
cording to Hartley the precipitated hydrates are treated with chlorine, 
by which eerie hydrate is left insoluble and the other hydrates eon- 
verted into soluble hypochlorites. 

Oxalate of cerium (Cerii Oxalas, U. S. 1'.) is decomposed at a 
dull red heat, 48 per rent, of a yellow, or, more generally, a salmon- 
colored, mixture of oxides remaining; usually the didymium present 
gives the ignited residue a reddish or reddish-brown color ; it is then 
soluble in boiling hydrochloric aoid (without effervescence ; indica- 
ting, indirectly, absence of earthy and other carbonates or oxalates) 



• 228 RARER METALLIC RADICALS. 

and the solution gives, with excess of a saturated solution of sul- 
phate of potassium, a crystalline precipitate of double sulphate of 
cerium and potassium. Alumina mixed with oxalate of cerium may 
be detected by boiling with solution of potash, filtering, and adding 
excess of solution of chloride of ammonium, when a white flocculent 
precipitate of hydrate of aluminium will be obtained. Oxide of zinc 
is revealed on boiling in potash and adding sulphide of ammonium, 
when white sulphide of zinc falls. The oxalic radical is recognized 
by neutralizing the potash solution by acetic acid and adding chloride 
of calcium ; white oxalate of calcium is then precipitated ; this pre- 
cipitate, though insoluble in acetic, should be wholly dissolved by 
hydrochloric acid. Acid or neutral cerium solutions give with 
acetate of sodium and peroxide of hydrogen a brownish-red color 
(Hartley). 

According to H. G. Greenish, most samples of oxalate of cerium 
have as impurities traces of lead, iron, and magnesium. 

MANGANESE. 

Symbol Mn. Atomic weight 54.8. 

Source. — Manganese is a constituent of many minerals, and as 
black oxide, or dioxide, or binoxide (Mn0 2 ) {Mangani Oxidum 
Nigrum, U. S. P., "containing not less than 66 per cent, of pure 
oxide, Mn0 2 "), or pyrolusite (from nvp, pur, fire, and ?,vctc, hisis, a 
loosing or resolving, in allusion to the readiness with which it is 
split up by heat into a lower oxide and oxygen), occurs frequently 
in abundance in the south-west of England, Aberdeenshire, and most 
of the countries of Europe. It is met with as a steel-gray mass of 
prismatic crystals or in black shapeless lumps. 

The chemical position of manganese is close to iron and three 
other metals still to be considered — cobalt, nickel, and chromium. 
Its atom apparently has sexivalent affinities, as seen in manganate 
of potassium, (K.,Mn0 4 ) ; but commonly it is quadrivalent (Mn IV ) or 
bivalent (Mn"). 

Uses. — Metallic manganese, which may be isolated by aid of so- 
dium, is used in alloy with iron in the manufacture of some vari- 
eties of steel. The black oxide is an important agent in the produc- 
tion of chlorine, the preparation of green and red disinfecting 
manganates, purple glass, and black glazes for earthenware. 

Reactions having both Synthetical and Analytical Interest. 

First Reaction. — Boil a few grains of black oxide of manga- 
nese with some drops of hydrochloric acid until chlorine ceases 
to be evolved ; add water, and filter ; the filtrate is a solution 
of manganous chloride (MnCl 2 ). 

Mn0 2 + 4HC1 = MnCl 2 + 2H 2 + Cl 2 . 

This is the reaction commonly applied in the preparation of chlo- 
rine gas. It is also a ready method of preparing a manganous salt 
for analytical experiments. Coupled with the application of re- 



MANGANESE. 229 

agents to the filtrate, the reaction is that by which a black powder 
or mineral would be recognized as black oxide of manganese. Black 
oxide of manganese dissolves in cold hydrochloric acid, forming 
a dark-brown solution of a higher chloride or chlorides, MnCl 3 , 
Mn 2 Cl 7 , or, possibly, MnCl 4 . 

Second Reaction. — -Heat a particle of a manganese compound 
with a grain or two of carbonate and hydrate of potassium and 
a fragment of nitrate or chlorate of potassium on platinum foil 
in the blowpipe-flame ; a green mass containing manganate of 
potassium (K 2 Mn0 4 ) results. Boil the foil in a little water ; 
the green manganate dissolves and. soon changes to solution of 
the purple permanganate of potassium (K 2 Mn 2 8 ). 

This is a delicate analytical test for manganese. 

The reaction is similar to that by which permanganate of potas- 
sium (Potassii Permanganas, U. S. P.) is prepared for use in vol- 
umetric analysis. Equations showing the exact action which occurs 
in making the salt according to the process of the British Pharma- 
copoeia have already been given in connection with the compounds 
of potassium (vide p. 76). The proportions of ingredients and details 
of the operation are as follows : — 

Reduce 3 J parts (for experiment each "part" may be -gth oz.) of 
chlorate of potassium to fine powder, and mix it with 4 of black 
oxide of manganese ; put the mixture into a porcelain basin, and 
add to it 5 parts of solid caustic potash, previously dissolved in 4 
parts of water. Evaporate to dryness, stirring diligently to prevent 
spirting." Pulverize the mass, put it into a covered Hessian or 
Cornish crucible, and expose it to a dull red heat (not higher) for 
an hour (20 or 30 minutes for quantities of 1 or 2 oz.), or till it has 
assumed the condition of a semi-fused mass. Allow to cool, pulver- 
ize, and boil with about 30 parts of water. Let the insoluble matter 
subside, decant the fluid, boil again with about 10 parts of water, 
again decant, neutralize the united liquors accurately with diluted 
sulphuric acid (or, better, carbonic acid gas), and evaporate till a 
pellicle forms. Set aside to cool and crystallize. Drain the crystal- 
line mass, boil it in 6 parts of water, and strain through a funnel 
the throat of which is slightly obstructed by a little" asbestos or 
gun-cotton. Let the fluid cool and crystallize, drain the dark 
purple slender prismatic crystals, and dry them by placing under 
a bell-jar over a vessel containing sulphuric acid. 

Instead of converting the manganate into permanganate by ebul- 
lition, by which one-third of the manganate is lost, Stadeler recom- 
mends chlorine to be passed through the cold solution until the 
green color is entirely changed to purple. 

Solutions of the manganates of potassium and sodium are in com- 
mon use as disinfectants under the name of Condy's Fluid. The\ act 
by oxidizing organic matter, the manganic or permanganic radical 
being reduced to black manganic oxide, or even a lower oxide. The 
reason for using asbestos instead of paper in filtering the solutions 
will now be understood. 



230 RARER METALLIC RADICALS. 

The changes in color which the green mass of the above process 
undergoes when dropped into warm water procured for it the old 
name of mineral chameleon. 

Third Reaction. — Make a borax bead by heating a fragment 
of the salt on the looped end of a platinum wire in the blow- 
pipe-flame until a clear transparent globule is obtained. Place 
on the bead a minute portion of a manganese compound, or 
touch it with a drop of solution. Again fuse the borax, using 
the point of the flame ; a bead of a violet or amethystine tint 
is produced. 

This is a good analytical reaction. It has also synthetical inter- 
est, illustrating the use of black oxide of manganese in producing 
common purple-tinted glass. 

Expose the bead to the reducing part of the flame, the part 
nearer to the blowpipe, where there are highly heated hydro- 
carbon gases greedy of oxygen ; the color disappears. 

This is owing to the reduction of the manganic compound to a 
manganous condition, in which it no longer possesses peculiar color- 
ing-power. This action also illustrates the use of black oxide of 
manganese in glass-manufacture. Glass when first made is usually 
of a green tint, owing to the presence of ferrous impurities ; the 
addition of manganic oxide to the materials converts the ferrous 
into ferric compounds, which have comparatively little colorific 
power, it itself being thereby reduced to manganous oxide, which 
also gives but little color. If excess of manganic oxide be added, a 
purple tint is produced. 

Reactions having Analytical Interest (Tests). 

Fourth Reaction. — Through a solution of a manganous salt 
acidified by hydrochloric acid pass sulphuretted hydrogen ; no 
decomposition occurs. Add ammonia ; the sulphydrate of am ■ 
monium thus formed causes the precipitation of a yellowish- 
pink or flesh-tinted precipitate of manganous sulphide (MnS) 
in a hydrous state. 

This reaction is characteristic, sulphide of manganese being the 
only flesh-colored sulphide known. The salt used may be the 
manganous chloride obtained in the first reaction 5 but such crude 
solutions usually give a black precipitate with sulphydrate of am- 
monium, owing to the presence of iron. The latter element may be 
precipitated, however, on adding excess of ammonia (and rapidly 
filtering, or oxygen will be absorbed and most of the manganese also 
precipitated (or on boiling the manganous solution with a very little 
carbonate of sodium, which attacks the ferric salt in preference to 
the manganous. Pure manganous chloride may be similarly ob- 
tained on boiling the impure solution with manganous carbonate 5 
the latter decomposes the ferric chloride with production of ferric 



MANGANESE. 231 

hydrate and more manganous chloride, and evolution of carbonic 
acid gas. 

To the recently precipitated manganous sulphide add acetic 
acid ; it is dissolved. 

This solubility enables manganese to be separated from nickel, 
cobalt, and zinc, whose sulphides are insoluble in weak acetic acid. 
To express the fact in another way — manganese is not precipitated 
by sulphuretted hydrogen from a solution containing free acetic acid 
only. 

Fifth Reaction. — To solution of manganous salt add am- 
monia ; a white precipitate of manganous hydrate (Mn2HO) 
falls. Add excess of ammonia ; spme of the precipitate is dis- 
solved, and may be detected in the quickly filtered solution by 
sulphydrate of ammonium. But both precipitate and solution 
rapidly absorb oxygen, the manganese passing into a more 
highly oxidized condition in which it is insoluble in ammonia. 

The fixed alkalies give a similar precipitate insoluble in excess. 
The precipitate rapidly absorbs oxygen, becomes brown, and grad- 
ually passes into a higher oxide. 

Sixth Reaction. — Heat a little black oxide of manganese in 
a test-tube with sulphuric acid ; oxygen is evolved and sul- 
phate of manganese formed (Mangani Sulphas, MnS0 4 ,4H 2 0, 
U. S. P.) ; add water, boil, filter, evaporate, and set aside to 
crystallize. Larger quantities are made in a similar manner. 

Sulphate of manganese (MnS0 4 ,5H 2 0) occurs in colorless or pale 
rose-colored, transparent crystals, which, when deposited from a solu- 
tion at a temperature between 68° and 86°, have the form of right 
rhombic prisms, and contain four molecules of water (U. S. P.). 
This salt is very soluble in water. Other sulphates containing 1 , 
2, 3, and 9 of water are known. The solution is not colored by 
tincture of nutgall (a black shows iron), but affords with caustic 
alkalies a white precipitate (Mn2HO), which, by exposure to the air. 
soon absorbs oxygen, and becomes brown. Sulphydrate of ammonium 
throws down a flesh-colored precipitate (MuS), and ferroeyanide of 
potassium a white one (Mn 2 Fcy). 

Many other reactions occur between manganese salts and va- 
rious reagents, but are of no particular synthetical or analyt- 
ical interest. 

A good method proposed by Crum, for detecting minute 
quantities of manganese, consists in adding dilute nitric acid 
and either red lead or the puce-colored oxide or peroxide oi' 
lead to the solution, and then boiling; a red tint, said to be 
due to permanganic acid, is imparted to the liquid. 



232 RARER METALLIC RADICALS. 

COBALT AND NICKEL. 

Krliss and Schmidt state (1889) that these very closely-allied 
metals, as hitherto known, are not true elements, but contain a 
third element, the oxide of which resembles, yet distinctly differs 
from, alumina and oxide of zinc. 



COBALT. 

Symbol Co. Atomic weight 58.6. 

Source. — Cobalt occurs sparingly in nature as the arsenide 
(CoAsg), or tin-white cobalt, and occasionally as a double arsenide 
and sulphide (CoAs 2 .CoS 2 ), or cobalt glance (from cjlanz, brightness, 
in allusion to its lustre). 

Uses. — Its chief use is in the manufacture of blue glass, the color 
of Avhich is due to a compound of cobalt, Cobalt is also the coloring 
constituent of smalt (from smelt, a corruption of melt), a finely-ground 
sort of glass, used as a blue pigment by paper-stainers and others, 
and employed also by laundresses to neutralize the yellowish ap- 
pearance of washed linen. 

The salts of cobalt may be obtained from the oxide (CoO), and the 
oxide from zajfre. a mixture of sand and roasted ore. 

Quantivalenee. — The atom of cobalt often exhibits quadrivalent 
affinities, but still more often exerts only bivalent powers (Co' 7 ). 
Cobalt has analytical relations with zinc, nickel, and manganese, 
and may be regarded as a member of the iron group. 

Analytical Reactions (Tests). 
First Analytical Reaction. — Pass sulphuretted hydrogen 
through an acidified solution of a salt of cobalt — the chloride 
(CoCl 2 ) or nitrate (Co2X0 3 ), for example; no decomposition 
occurs. Add ammonia ; the sulphydrate of ammonium thus 
formed causes the precipitation of black sulphide of cobalt (CoS). 

The moist precipitate slowly absorbs oxygen from the air, becom- 
ing converted into sulphate of cobalt (CoSOJ. 

Second Analytical Reaction. — Add ammonia gradually to a 
cobalt solution ; a blue precipitate of impure lrvdrate of cobalt 
(Co2HO) falls. Add excess of ammonia; the precipitate is 
dissolved, yielding a liquid somewhat more reddish-brown than 
the original solution. 

A similar precipitate is given by the fixed alkalies, insoluble in 
excess. 

Third Analytical Reaction. — Make a borax bead by heating 
a fragment of the salt on the looped end of a platinum wire in 
a blowpipe-flame until a clear transparent globule is obtained. 
Place on the bead a minute portion of a cobalt compound, or 



NICKEL. 233 

touch it with a drop of solution. Again fuse the borax ; a 
blue bead results. 

This is a delicate test for cobalt. From what has previously been 
said, it will be seen that this experiment has also considerable syn- 
thetical interest. 

Fourth Analytical Reaction. — To a solution of a salt of co- 
balt add two or three drops of hydrochloric acid, then excess 
of solution of cyanide of potassium, and boil for ten minutes ; 
oxygen is absorbed, and cobalticyanide of potassium (K 6 Co 2 Cy 12 ) 
formed. Add hydrochloric acid, and boil the mixture (in a 
fume-cupboard, to avoid inhalation of any hydrocyanic acid) ; 
the excess of cyanide of potassium is thus decomposed, but the 
cobalticyanide is unaffected. Now add excess of solution of 
potash ; the cobalticyanide of potassium probably is decom- 
posed, but the cobalt remains dissolved in the alkaline liquid. 

Nickel under similar circumstances is precipitated, the reaction 
thus affording means of separating these closely allied metals from 
each other. 

Other Reactions between a cobalt solution and different re- 
agents may be performed, and various precipitates obtained ; 
but these have no special analytical interest. 

Invisible Ink. — Many salts of cobalt containing water of 
crystallization are light red, the anhydrous more or less blue. 
Prove this by writing some words on paper with a solution of 
chloride of cobalt sufficiently dilute for the characters to be in- 
visible when dry ; hold the sheet before a fire or over a flame ; 
the letters at once become visible, distinct, and of a blue color. 
Breathe on the words, or set the sheet aside for a while ; the 
characters are once more invisible, owing to absorption of moist- 
ure. Hence solution of chloride of cobalt forms one of the 
so-called sympathetic inks. 

NICKEL. 

Symbol Ni. Atomic weight 58.6. 
The ores of these metals are commonly associated in nature. In- 
ieed, it is from speiss, an arsenio-sulphide of nickel obtained in the 
manufacture of smalt, a pigment of cobalt already mentioned, that 
most of the nickel met with in commerce is obtained. It is much 
used in the preparation of the white alloy known as German or 
nickel silver, and for plating iron. 

QuanUvalcnce. — Nickel exerts bivalent activity (Ni") in its 
ordinary compounds. Its salts and their solutions arc usually 
green. They are chiefly made, directly or indirectly, from the 
metal itself. 



234 RARER METALLIC RADICALS. 

Analytical Reactions (tests). 
First Analytical Reaction.— Pass sulphuretted hydrogen 
through an acidified solution of a salt of nickel — chloride (NiCL), 
nitrate (Ni2N0 3 ), or sulphate (NiSOJ ; no decomposition oc- 
curs. Add ammonia ; the sulphydrate of ammonium thus formed 
causes the precipitation of black sulphide of nickel (NiS). 

Note. — When sulphate of nickel is precipitated by the direct addi- 
tion of the common yellow solution of sulphydrate of ammonium, 
which always contains free sulphur, there is much difficulty in filter- 
ing the mixture, owing to the slight solubility of sulphide of nickel 
in the reagent and the formation of some sulphate of nickel (NiS0 4 ), 
oxygen being absorbed from the air by the sulphide. This may be 
avoided by warming the mixture and using freshly-made sulphydrate 
of ammonium, in which the sulphide of nickel is insoluble ; or, where 
practicable, the salt of nickel may be precipitated from an ammo- 
niacal solution by sulphuretted hydrogen. 

Second Analytical Reaction. — Add ammonia drop by drop 
to a nickel solution ; a pale-green precipitate of hydrate of 
nickel (Ni2HO) falls, especially on boiling the mixture. Add 
excess of ammonia ; the precipitate dissolves, yielding a bluish 
rather than the original green-colored solution. 

A similar precipitate is given by the fixed alkalies, insoluble. 
in excess. 

Third Analytical Reaction. — Nickel salts color a borax bead, 
when hot, a reddish-yellow tint ; the reaction is not very ser- 
viceable analytically. 

Fourth Analytical Reaction. — To a solution of a salt of 
nickel add solution of cyanide of potassium ; cyanide of nickel 
(NiCy 2 ) is precipitated. Add excess of solution of cyanide 
of potassium ; the precipitate is dissolved with formation of 
double cyanide of nickel and potassium (NiCy 2 ,2KCy). Next 
add hydrochloric acid, and boil the mixture (in a fume-cup- 
board), adding a little hydrochloric acid from time to time 
until all smell of hydrocyanic acid has disappeared. Lastly, 
add excess of solution of potash ; hydrate of nickel is precipi- 
tated. 

Qualitative Separation of Cobalt and Nickel. 

The foregoing reaction serves for the separation of nickel from 
cobalt. On adding excess of hydrochloric acid to a solution contain* 
ing the two metals, together with cyanide of potassium, a precipi- 
tate of cyanide of nickel and cobaltieyanide of nickel occurs. By 
ebullition with excess of hydrochloric acid the cyanide of nickel is 
decomposed, chloride of nickel going into solution. On then adding 
ex<-ess of potash, hydrate of nickel is precipitated. The cobalticy- 
anide of nickel is not decomposed by the acid ; but is by the alkali. 



NICKEL. 235 

its cobalt going into solution and its nickel remaining insoluble as 
hydrate. After filtering off the nickel, cobalt is detected in the fil- 
trate by evaporating to dryness and testing the residue with borax 
in the blowpipe-flame. 

[This process requires much practice for its successful performance, 
and need not be attempted by pupils whose studies are restricted to 
medicine and pharmacy.) 

The value of this method (Skey and Davies) turns on the 
facts that ferridcyanide of nickel is not a colored body, while 
ferridcyanide of cobalt is reddish-brown, and that ferridcyano- 
gen has apparently, in ammoniaccd solution, greater affinity for 
cobalt than for nickel, while ferrocyanogen has, apparently, 
greater affinity for nickel than for cobalt. The formulae of 
these so-called ferrocyanides and ferridcyanides of cobalt and 
nickel have not been definitely ascertained. 

Other reactions between a nickel solution and various re- 
agents give, in many cases, insoluble precipitates which, from 
their green color, are occasionally useful in distinguishing nickel 
from allied elements. 

CHROMIUM. 

Symbol Cr. Atomic weight 52.4. 

Source. — The chief ore of chromium is chrome ironstone, a mix- 
ture of the oxides of, the metals (FeO,Cr 2 3 ), occurring chiefly in 
the United States and Sweden. In constitution it seems to resemble 
magnetic iron ore (FeO,Fe 2 3 ). The metal may be isolated by aid 
of sodium. 

Preparation of Red Chr ornate of Potassium. — On roasting the 
powdered ore with carbonate of potassium and nitre, yellow chro- 
mate of potassium (K 2 Cr0 4 ) is obtained ; the mass, treated with acid, 
yields reel or bichromate (K 2 Cr0 4 ,Cr0 3 ) (Potassii Bickromas, V. S. 
P.); from this salt other chromates are prepared, and by reduction, 
as presently explained, the salts of chromium itself. The yellow 
and orange chromates of lead are largely used as pigments. 

Note on Constitution. — Red chromate of potassium is a somewhat 
abnormal salt, containing, probably, neutral chromate associated 
with chromic anhydride, and hence termed anhydrochromate of po- 
tassium. The value of chromates as chemical reagents is alluded 
to in connection with chromate of barium (p. 103). Heated strongly 
in a crucible, red chromate of potassium splits up into yellow (.Ino- 
rnate, glistening oxide of chromium, and oxygen ; red chromate 
of ammonium into oxide of chromium, water, and nitrogen 
(NlI. l ),0r0. l ,Cr0 3 = Cr 2 ? + 411,0 f N 2 . 

Quaniivalence. — Chromium stands in close chemical relation to 
iron, aluminium, and manganese. Its atom is sexivalent if the for- 
mula of the fluoride (CrF 6 ) be correct. Like iron and aluminium, 
it is trivalent, as seen in chromic chloride (Cr a Cl 6 ), but sometimes 
exerts only bivalent activity, as in chromous chloride (CrCl,). 



236 RARER METALLIC RADICALS. 

Passage of Chromium from the Acidulous to the Basyhus 
Side of Salts. — Through an acidified solution of red chromate 
of potassium pass sulphuretted hydrogen ; sulphur is deposited, 
and a green salt of chromium remains in solution, chloride 
(Cr 2 Cl 6 ) if hydrochloric acid be used, and sulphate (Cr 2 3S0 4 ) 
if sulphuric be the acid employed. Boil the liquid to expel 
excess of sulphuretted hydrogen, filter, and reserve the solution 
for subsequent experiments. (For an equation of this reaction, 
see p. 237.) 

Alcohol, sugar, or almost any substance which is tolerably liable 
to oxidation, will answer as well as sulphuretted hydrogen. 

Sulphate of' chromium (Cr 2 3SOJ, like sulphate of aluminium 
(Al 2 3SOJ, unites with alkali-metal sulphates to form alums, which 
resemble common alum both in crystalline form, and, as far as we 
know, in internal structure : they are of purple color. 

Reactions. 

Chromium as Chromic Acid, or other Chromate. — This is 
the state in which chromium will usually be met with, the most 
common salt being the red chromate or bichromate of potas- 
sium. Mix four volumes of a cold, saturated aqueous solution 
of red chromate of potassium with five of oil of vitrol ; on 
cooling, chromic anhydride (Cr0 3 ), Acidum Chromicum, IT. S. 
P., or anhydrous chromic acid, separates' in crimson needles. 
After well draining, the crystals may be freed from adhering 
sulphuric acid by washing once or twice with nitric acid : the 
latter may be removed by passing dried and slightly warmed 
air through a tube containing the ciystals. It may be quite 
freed from sulphuric acid by one or two recrystallizations. In 
contact with moisture chromic anhydride takes up water and 
forms solution of true chromic acid (H 2 Cr0 4 ), 1 part of the an- 
hydride and 3 parts of water forming the Liquor Arid Chro- 
mici, B. P. Chromic anhydride is a powerfully corrosive oxi- 
dizing agent. It melts between 356° and 374° F., and at a high 
temperature decomposes, yielding oxide of chromium and oxy- 
gen ; it oxidizes organic substances with great violence. 

The oxygen in chromic acid and other chromates, and in manga- 
natcs, permanganates, black oxide of manganese, and puce-colored 
oxide of lead, is in a physically different state from that in peroxide 
of hydrogen, peroxide of barium, and similar compounds. On 
bringing chromic acid or the above acidified solution of red chro- 
mate of potassium into contact with solution of peroxide of hydro- 
gen, a strong effervescence of oxygen ensues. According to Schon- 
bein and Brodie the oxygen of chromic acid is in the negative or 
ozonic state, while that of peroxide of hydrogen is in the positive or 



CHROMIUM. 237 

so-called antozonic condition. Both are equally active, but neutral- 
ize each other, forming neutral or ordinary oxygen. 

In the analytical examination of solutions containing chro- 
mates, the chromium will always come out in the state of green 
chromic hydrate, along with ferric hydrate and alumina, the 
prior treatment by sulphuretted hydrogen reducing the chro- 
mium in the molecule to the lower state, thus : — 

K 2 O0 4 ,O0 3 + 8HC1 + 3H 2 S = Cr 2 Cl 6 + 2KC1 + 7H 2 -f S 3 . 

Chromium having been found in a solution, its condition as 
chromate may be ascertained by applying to the original solu- 
tion salts of barium, mercury, lead, and silver. (See the vari- 
ous paragraphs relating to those metals.) 

Ba2N0 3 gives yellow BaCr0 4 with chromates. 
Hg,2N0 3 " red Hg 2 O0 4 
AgN0 3 " " Ag 2 Cr0 4 

" " " Ag 2 Cr0 4 ,Cr0 3 with bichromates. 

Pb2C 2 H 3 2 " yellow PbCr0 4 with both. 

Nitrate of barium does not completely precipitate bichromates, 
bichromate of barium being soluble in water ; the chromate of ba- 
rium is insoluble in water or acetic acid, but soluble in hydro- 
chloric or nitric acid. Mercurous nitrate does not wholly pre- 
cipitate bichromates: mercuric nitrate or chloride only partially 
precipitates chromates, and does not precipitate bichromates. The 
mercurous chromate is insoluble, or nearly so, in diluted nitric acid. 
The silver chromates are soluble in acids and alkalies. Acetate of 
lead precipitates chromates and bichromates, acetic acid being set 
free in the latter case. 

A delicate reaction for dry chromates will be found in the 
formation of chlorochromic anhydride (Cr0 2 Cl 2 ). A small por- 
tion of the chromate is placed in a test-tube with a fragment 
of dry chloride of sodium and a drop or two of oil of vitrol, 
and the mixture heated ; red irritating fumes of chlorochromic 
anhydride are evolved, and condense in dark-red drops on the 
side of the tube. 

Large quantities of pure distilled chlorochromic anhydride are 
obtained by the same reaction, the operation being conducted in a 
retort, with thoroughly dry materials, for the compound is decom- 
posed by water. It may be regarded as chromic anhydride in which 
an atom of oxygen is displaced by an equivalent quantity (two atoms) 
of chlorine. It is not used in medicine, but is of interest to the 
chemical student as being an illustration of a class o\' similar bodies 
— chloro-acidulous or chlbro-anhydrous compounds. The reaction is 
also occasionally serviceable for the detection of chlorides. 



238 RARER METALLIC RADICALS. 

Analytical Reactions of Chromium Salts (Tests). 

First Analytical Reaction. — To solution of a salt of chro- 
mium (chloride, sulphate, or chrome alum) add sulphydrate of 
ammonium ; a bulky green precipitate of chromic hydrate 
(Cr 2 6HO), containing a large quantity of water (7 molecules, 
7H,0), is precipitated. 
Cr"ci 6 -f 6XH.HS + 6H,0 = Cr 2 6HO - 6NH.C1 -f 6H 2 S. 

Second Analytical Reaction. — To solution of a chromium 
salt add ammonia ; chromic hydrate is precipitated, insoluble 
in excess. 

Third Analytical Reaction. — To solution of a chromium salt 
add solution of potash or soda, drop by drop ; chromic hydrate 
is precipitated. Add excess of the fixed alkali ; the precipitate 
is dissolved. Boil well the solution ; the chromic hydrate is 
reprecipitated. 

Iron. Chromium, and Aluminium Salts, chemically so alike, may 
be separated by this reaction. Ferric hydrate is insoluble in solu- 
tions of the fixed alkalies, cold or hot : chromium hydrate, soluble 
in cold but not in hot : hydrate of aluminium, in both. To a solu- 
ti( n containing all three metals, therefore, add potash or soda. stir. 
and filter: the iron is thrown out : boil the filtrate, and filter; the 
chromium is thrown out : neutralize the filtrate by acid, and then 
add ammonia : the aluminium is thrown out. Xote. however, that 
ferric hydrate will prevent hydrate of chromium being dissolved by 
potash or soda if the ferric hydrate is in considerable excess. Before 
concluding that chromium is entirely absent, the 4th reaction should 
be performed. The hydrates of iron, chromium, and aluminium are 
insoluble in ammonia, and may therefore be easily separated from 
the hydrates of the somewhat analogous metals zinc, cobalt, nickel, 
and manganese. 

Fourth Analytical Reaction. — Add a salt of chromium (either 
of the above precipitates of chromic oxide or the dry residue of 
the evaporation of a few drops of a solution of a chromium 
salt) to a few grains of nitre and carbonate of sodium on plat- 
inum foil, and fuse the mixture in the blowpipe-flame ; a yellow 
mass of chromate of potassium and sodium (KXaCr0 4 ) is 
formed. Dissolve the mass in water, add acetic acid to de- 
compose excess of carbonate, and apply the reagents for chro- 
inates. 

This is a delicate and useful reaction if carefully performed. 

TIN. 

Symbol Sn. Atomic weight 117.7. 
Source. — The chief ore of tin is stannic oxide (Sn(X). occurring 



TIN. 239 

in veins under the name of tinstone, or in alluvial deposits as stream- 
tin. The oldest mines are those of Cornwall. Much tin is now im- 
ported from Australia. 

Preparation. — The metal is obtained by reducing the roasted and 
washed ore by charcoal or anthracite* coal at a high temperature, 
and is purified by slowly heating, when the pure tin, fusing first, is 
run off, a somewhat less fusible alloy of tin with small quantities of 
arsenicum, copper, iron, or lead remaining. The latter is known as 
block tin; the former heated till brittle and then hammered or let 
fall from a height splits into prismatic fragments, resembling starch 
or columnar basalt, and is named dropped or grain tin. Good tin 
emits a crackling noise in bending, termed the cry of tin, caused by 
the friction of its crystalline particles on each other. 

Uses. — Tin is an important constituent of such alloys as pewter, 
Britannia metal, solder, speculum-metal, bell-metal, gun-metal, and 
bronze. It is very ductile, and may be rolled into plates or leaves, 
known as tinfoil, varying from 2wu to t^oo 0I> an i ncn i* 1 thickness. 
Common tin foil, however, usually contains a large proportion of 
lead. The reflecting surface of looking-glasses was, formerly, always 
an amalgam of tin and mercury, produced by carefully sliding a 
plate of glass over a sheet of tin foil on which mercury had been 
rubbed, and then excess of mercury poured ; but pure silver, de- 
posited from a solution, is now largely employed. Pins are made 
of brass wire, on which tin is deposited. Tin plate, of which com- 
mon utensils are made, is iron alloyed with tin by dipping the acid- 
cleansed sheet into melted tin covered with oil, which, by dissolving 
any trace of oxide, or, perhaps, by preventing oxidation, enables 
the tin more completely to alloy with the iron. Tin tacks are in 
reality "tinned iron tacks; a tin nail would be too soft to drive into 
wood. Tin may be granulated by melting and triturating briskly 
in a hot mortar, by shaking melted tin in a box on the inner sides 
of which chalk has been rubbed, or, in thin little bells or corrugated 
fragments (Granulated Tin, B. P.), by melting in a ladle, and im- 
mediately it is fluid, pouring from the height of a few feet into water. 
Powdered tin has been used medicinally as a mechanical irritant to 
promote expulsion of worms. The hair of the pods of Kiwach or 
Cowhage (Hindustani) (Mucuna prnricns, P. I.) is almost the only 
medicine (excluding diluents and dentifrices) which acts in such a 
directly mechanical manner. 

The chemical position of tin among the metals is close to that of 
arsenicum and antimony. Its atom is quadrivalent and bivalent. 
The two classes of salts are termed stannic and stannous respec- 
tively. They are all made directly or indirectly from the metal 
itself. 



* Anthracite (from ay6pa§, anthrax, a burning coal) or stone coal differs 
from the ordinary bituminous or caking coal in containing less volatile 
matter, and, therefore, in burning without flame. It gives a higher 
temperature, and from its non-caking properties is, in furnace opera- 
tions, more manageable than bituminous coal. 



240 RARER METALLIC RADICALS. 

Reactions haying (a) Synthetical and (6) Analytical 
Interest. 

(a) Synthetical Reactions. 

Chloride of Tin. Stannous Chloride. 
First Synthetical Reaction. — Warm a fragment of tin with 
hydrochlorous acid ; hydrogen escapes and solution of stannous 
chloride (SnCl 2 , perhaps Sn 2 Cl 4 ) is formed. It may be retained 
for future experiments. 

One ounce of tin dissolved in three fluidounces of hydrochloric 
acid and one of water, and the resulting solution diluted to five fluid- 
ounces, constitutes the " Solution of Stannous Chloride,". B. P. 

Solid Stannous Chloride. — By evaporation of the above solution 
stannous chloride is obtainable in crystals (SnCl 2 ,2H 2 0). It is a 
powerful reducing agent, even a dilute solution precipitating gold, 
silver, and mercury from their solutions, converting ferric and cupric 
into ferrous and cuprous salts, and partially deoxidizing arsenic, 
manganic, and chromic acids. It absorbs oxygen from the air, and 
is decomposed when added to a large quantity of water unless some 
acid be present. It is used as a mordant in dyeing and calico- 
printing. 

Perchloride of Tin. Stannic Chloride. 
Second Synthetical Reaction. — Through a portion of the so- 
lution of the stannous chloride of the previous reaction pass 
chlorine gas ; solution of stannic chloride (SnCl 4 ) is formed. 
Or add hydrochloric acid to the stannous solution, boil, and 
slowly drop in nitric acid until no more fumes are evolved j 
again stannic chloride results. Reserve the solutions for sub- 
sequent experiments. 

Stannic Oxide, or Anhydride, and Stannates. 

Third Synthetical Reaction. — Boil a fragment of tin with 
nitric acid, evaporate to dryness, and strongly calcine the resi- 
due ; light buff-tinted stannic anhydride (Sn0 2 ) is produced. 
Heat the stannic anhydride with excess of solid caustic pot- 
ash or soda ; stannate of the alkali metal (K 2 Sn0 3 or Na 2 Sn0 3 ) 
results. Dissolve the stannate in water, and add hydrochloric 
acid ; white, gelatinous stannic acid (H 2 Sn0 3 ) is precipitated. 
Stannic acid is also obtained on adding an alkali to solution of 
stannic chloride ; it is soluble in excess of acid or alkali. 

The product of the action of nitric acid on tin is also an acid, but 
from its insolubility in hydrochloric and other acids is different from 
ordinary stannic acid. It is termed metastannic acid (from fiera, 
nieta, beyond), and probably has a composition expressed by the 



TIN. 241 

formula H 10 Sn 5 O 15 . (Vide Index, "Isomerism.") It is also pro- 
duced on gently heating stannic acid: — 

5H 2 Sn0 3 = H 10 Sn 5 O 15 

Stannic acid. Metastannic acid. 

Metastannates have the general formula M 2 H 8 Sn 5 15 . Both acids 
yield buff-colored stannic oxide or anhydride (Sn0 2 ) when strongly 
heated. The latter is employed in polishing plate under the name 
of putty powder. Stannate of sodium (Na2Sn0 3 ,4H 2 0) is used as a 
mordant by dyers and calico-printers under, the name of tin pre- 
pare-liquor. 

(b) Reactions having Analytical Interest ( Tests). 
Stannous or Stannic Salts. — Heat any solid tin compound 
with a mixture of cyanide of potassium and carbonate of so- 
dium on charcoal by the inner flame of the blowpipe. Glob- 
ules of tin separate, having, when cut by a knife, character- 
istic brightness and hardness. 

STANNOUS SALTS. 

First Analytical Reaction. — Through a dilute solution of a 
stannous salt (stannous chloride, for example ; see previous 
page) pass sulphuretted hydrogen gas ; brown stannous sul- 
phide (SnS) is precipitated. Pour off the supernatant liquid, 
add ammonia to the moist precipitate (to neutralize acid), and 
lastly yellow sulphydrate of ammonium solution ; the precipi- 
tate is dissolved. 

Aqueous solution of sulphydrate of ammonium becomes yellow 
when a day or two old, and then contains excess of sulphur, that 
element having become displaced by oxygen absorbed from the air ; 
hence, in the above reaction, the stannous sulphide (SnS), in dis- 
solving, becomes stannic sulphide (SnS 2 ) ; for the latter is pre- 
cipitated on decomposing the alkaline liquid by an acid. 

Second Analytical Reaction. — To solution of a stannous salt 
add solution of potash or soda ; white stannous hydrate falls 
(Sn2HO). Add excess of the alkali ; the precipitate dissolves. 
Boil the solution ; some of the tin is precipitated as blackish 
stannous oxide (SnO). 

Ammonia gives a similar precipitate, insoluble in excess. The 
alkaline carbonates do the same, carbonic acid gas escaping. 

STANNIC SALTS. 

Third Analytical Reaction. — Through a solution oi' a stannic 
salt (stannic chloride, for example ; see page 239) pass sulphur- 
etted hydrogen gas; yellow stannic sulphide (SnS a ) is precipi- 



242 RARER METALLIC RADICALS. 

tated. Pour off the supernatant liquid, and to the moist pre- 
cipitate add ammonia (to neutralize acid), and then sulphydrate 
of ammonium ; the precipitate dissolves. 

Note. — In precipitating stannic sulphide the presence of too much 
hydrochloric acid must be avoided ; the formation of the precipitate 
is also facilitated if the solution be warmed. Stannic sulpiride, like 
the sulphide of arsenicum and antimony, dissolves in a solution of 
alkaline sulphide or sulphydrate, with formation of definite crys- 
tallizable sulphostannates (M^SnSg). 

Anhydrous stannic sulphide, prepared by sublimation, has a yel- 
low or orange lustrous appearance, and is used by decorators as 
. bronzing-powder. It is sometimes termed mosaic gold. 

Fourth Analytical Reaction. — To solution of a stannic salt 
add potash or soda ; white stannic acid falls (H 2 Sn0 3 ). Add 
excess of the alkali ; the precipitate dissolves. Boil the mix- 
ture ; no reprecipitation occurs — a fact enabling stannic to be 
distinguished from stannous salts. 

Ammonia gives a similar precipitate, soluble, but not readily, in 
excess. The fixed alkali-metal carbonates do the same, carbonic 
acid gas escaping •, after a time the stannic salt is again deposited, 
probably as stannate of the alkali metal. Carbonate of ammonium 
and acid carbonates of alkali metals give a precipitate of stannic 
acid insoluble in excess. 

Antidotes. — In cases of poisoning by tin salts (dyer's tin liquor, 
e. g.), solution of carbonate of ammonium should be given. White 
of egg is also said to form an insoluble precipitate with compounds 
of tin. Vomiting should be speedily induced, and the stomach- 
pump quickly applied. 

GOLD. 

Symbol Au. Atomic weight 196.85. 

Source. — Gold occurs in the free state in nature, occasionally in 
nodules or nuggets, but commonly in a finer state of division termed 
gold dust. 

Preparation. — Gold is separated from the sand, crushed quartz, 
or other earthy matter with which it may be associated, by agita- 
tion with water, when the gold, from its relatively greater specific 
gravity, falls to the bottom of the vessel first, the lighter mineral 
matter being allowed to run off with the water. From this rich 
sand the gold is dissolved out by mercury, the amalgam filtered, 
and afterwards distilled, when the mercury volatilizes and gold 
remains. The amalgamation may be much facilitated by the use 
of a small proportion of sodium, as already described in treating 
of silver. 

Pure gold is too soft for general use as a circulating medium. 
Gold coin is an alloy of copper and gold, that of Great Britain 
containing 1 of the former to 11 of the latter, or 8£ per cent, of 
copper, that of France, Germany, and the United States about 10 



gold. 243 

per cent. Jewellers gold varies in quality, every 24 parts containing 
18, 15, 12, or 9 parts of gold, the alloys being technically termed 
18, 15, 12, or 9 carat fine. Articles made of the better qualities are 
usually stamped by authority. Trinkets of inferior intrinsic worth 
are commonly thinly coated with pure gold by electro-deposition or 
otherwise. The so-called Mystery gold is an alloy of about 1 part 
platinum and 2 parts copper with a little silver. It resists the ac- 
tion of strong nitric acid. The action of aqua regia, and then am- 
monia, reveals its cupric character. Gold leaf(U. S. P.) is nearly 
pure gold passed between rollers till it is about g-^o of an inch in 
thickness, and then hammered between sheets of animal membrane 
termed gold-beater's skin and calf-skin vellum till it is TeoWo or 
20W000 °f an i ncn m thickness. It may even be hammered till 
280,000 leaves would be required to form a pile an inch thick. 

Gold Coinage. — The weight of gold is expressed in Great Britain 
in ounces troy and decimal parts of an ounce, and the metal is always 
taken to be of standard fineness (11 gold and 1 alloy) unless other- 
wise described. The degree of fineness of gold, as ascertained by 
assay, is expressed decimally, fine pure gold (" gold free from metallic 
impurities," B. P.) being taken as unity, or 1.000. Thus gold of 
British standard is said to be 0.9166 fine, of French standard 0.900 
fine. The legal weight of the sovereign is 0.2568 ounce of standard 
gold, or 123.274 grains. The weight came from one pound of stand- 
ard gold (5760 grains) being coined into 44J guineas. Gold coins 
are legal tender to any amount, provided that the weight of each 
sovereign does not fall below 122.5 grains, or in the case of a half 
sovereign 61.125 grains; these are the " least current" weights of 
the coins. 

Note. —In chemical analysis gold comes out among the sulphides 
of the metals precipitated by sulphuretted hydrogen ; and of those 
sulphides, it, like the sulphides of tin, antimony, and arsenicum, is 
soluble in sulphydrate of ammonium. 

Quantivalence. — Gold is trivalent (Au /7/ ), but in some compounds 
univalent (Au'). 

Reactions. 
Synthetical Reactions. — Place a fragment of gold (e. g., gold 
leaf) in ten or twenty drops of aqua regia (a mixture of three 
parts of nitric and four or five of hydrochloric acid), and set 
the test-tube aside in a warm place ; solution of perchloride of 
gold or auric chloride (AuCl 3 ) results. When the metal is 
dissolved, evaporate nearly to dryness to remove most of the 
excess of fluid, dilute with water, and retain the solution for 
subsequent experiments. Sixty grains of gold treated thus, 
and the resulting chloride dissolved in five ounces of distilled 
water, constitute "Solution of Perchloride of Gold," 1>. P. The 
pcrsalt itself is very deliquescent. A compound of the chloride 
of gold and sodium, in molecular proportions, crystallizes 
readily and is more stable. 



244 RARER METALLIC RADICALS. 

Au 2 + 2HN0 3 + 6HC1 = 2AuCl 3 + 2N0 + 4H 2 0. 

This reaction has analytical interest also ; for in examining a sub- 
stance suspected to be or contain metallic gold, solution would have 
to be effected in the above way before reagents could be applied. 
Gold is insoluble in hydrochloric, nitric, and the weaker acids. 

Chloride of Gold and Sodium (Auri et Sodii Chloridum, U. S. P.) 
is " a mixture composed of equal parts of dry chloride of gold and 
chloride of sodium." 

Analytical Reactions ( Teats). 

First Analytical Reaction. — Through a few drops of solution 
of an auric salt (the chloride, AuCl 3 , is the only convenient 
one) pass sulphuretted hydrogen ; brown auric sulphide (Au 2 S 3 ) 
is precipitated. Filter, wash, and add yellow sulphydrate of 
ammonium solution ; the precipitate dissolves. 

Second Analytical Reaction. — To solution of a salt of gold 
acid ferrous salt, and set the tube aside ; metallic gold is pre- 
cipitated, a ferric salt remaining in solution. 

This is a convenient way of preparing pure gold, ox fine gold as 
it is termed, or of working up the gold residues of laboratory opera- 
tions. The precipitate, after boiling with hydrochloric acid, washing 
and drying, may be obtained in a button by mixing with an equal 
weight of borax or acid sulphate of potassium and fusing in a good 
furnace. 

Third Analytical Reaction. — Add a few drops of dilute so- 
lutions of stannous and stannic chloride to a considerable 
quantity of distilled water ; pour the liquid, a small quantity 
at a time, in a very dilute solution of auric chloride (AuCl 3 ), 
well stirring ; the mixture assumes a purple tint, and flocks of 
a precipitate known as the Purple of Cassius (from the name 
of the discoverer, M. Cassius) are produced. 

The same compound is formed on immersing a piece of tin foil in 
solution of auric chloride ; it is said to be a mixture of auric, aurous, 
stannic, and stannous oxides. It is the coloring agent in the finer 
varieties of ruby glass. 

PLATINUM. 

Symbol Pt. Atomic weight 195. 

Source. — Platinum, like gold, usually occurs in nature in the free 
state, the chief sources of supply being Mexico, Brazil, and Siberia. 
It is separated from the alluvial soil by washing. 

Uses. — The chief use of platinum is in the construction of foil, wire, 
crucibles, spatulas, capsules, evaporating-dishes, and stills for the 
use of the chemical analyst or manufacturer. It is tolerably hard, 
fusible with very great difficulty, not dissolved by hydrochloric, nitric, 



PLATINUM. 245 

or sulphuric acid, and only slightly affected by alkaline substances. 
It is attacked by aqua regia, with production of perch loride of plat- 
inum or platinic chloride (PtCl 4 ,5II 2 0). It forms fusible alloys with 
lead and other metals, and with phosphorus a phosphide, which 
easily melts. Neither of these substances, therefore, nor mixtures 
which may yield a metal, should be heated in platinum vessels. 

The chemical position of platinum among the elements is close to 
that of gold. Its atom is quadrivalent in some compounds, in others 
apparently bivalent (Pt 7/ ). The higher salts are termed platinic, the 
lower platinous. 

The specific gravity of platinum is 21.5 ; and that of iridium, an 
allied metal, 22A. 

Reactions. 

Perchloride of Platinum. Platinic Chloride. 

Synthetical Reaction. — Place a fragment of platinum in a 
little aqua regia and set the vessel aside in a warm place, add- 
ing mere acid from time to time if necessary ; solution of per- 
chloride of platinum (PtCl 4 ) results. Evaporate the solution 
to remove excess of acid, and complete the desiccation over a 
water-bath. Dissolve the residue in water, and retain the solu- 
tion for subsequent experiments, and as a reagent for the pre- 
cipitation of salts of potassium and ammonium. 

A quarter of an ounce of platinum treated in the above manner, 
and the resulting chloride dissolved in five ounces of water, con- 
stitutes " Solution of Perchloride of Platinum," B. P., or 1 part of 
pure platinic chloride (PtCl 4 ,5IL,0) dissolved in 20 of distilled water 
gives " Test Solution of Platinic Chloride," U. S. P. 

This reaction has analytical interest also ; for in examining a suit- 
stance suspected to be or to contain metallic platinum, solution would 
have to be thus effected before reagents could be applied. 

Analytical Reactions (Tests). 
First Analytical Reaction. — Through a few drops of a solu- 
tion of a platinic salt (PtCl 4 is the only convenient one), to 
which an equal quantity of solution of chloride of sodium has 
been added, pass sulphuretted hydrogen ; dark-brown platinic 
sulphide (PtS 2 ) is precipitated. Filter, wash, and add sulphy- 
drate of ammonium ; the precipitate dissolve's. 

If chloride of sodium be not present in the above reaction, the pre- 
cipitated sulphide will contain platinous chloride, and may detonate 
if heated. 

Second Analytical Reaction,. — Add excess oi' solution of car- 
bonate of sodium and some sugar to solution of perchloride oi' 
platinum and boil; a precipitate of metallic platinum falls. 

Platinum Black is the name of this precipitate. It possesses in 



246 RARER METALLIC RADICALS. 

a high degree a quality common to many substances, but largely 
possessed by platinum, namely, that of absorbing or occluding gases. 
In its ordinary state, after well washing and drying, it absorbs from 
the air and retains many times its bulk of oxygen. A drop of ether 
or alcohol placed on it is rapidly oxidized, the platinum becoming 
hot. This action may be prettily shown by pouring a few drops of 
ether into a beaker (one having portions of the top and sides broken 
off answers best), loosely covering the vessel with a card, and sus- 
pending within the beaker a platinum wire, one end being attached 
to the card by passing through its centre, the other terminating in 
a short coil or helix near the surface of the ether ; on now warming 
the helix in a flame and then rapidly introducing it into the beaker, 
it will become red hot, and continue to glow so long as there is ether 
in the vessel. In this experiment real combustion goes on between 
the ether vapor and the concentrated oxygen of the air, the products 
of the oxidation revealing themselves by their odor. 

Third Analytical Reaction. — To solution of perchloride of 
platinum add solution of chloride of ammonium ; a yellow 
granular precipitate of double chloride of platinum and ammo- 
nium (PtCl 4 ,2AmCl) falls. When slowly formed in dilute so- 
lutions, the precipitate is obtained in minute orange prisms. 

Chloride of potassium (KC1) gives a similar precipitate (PtCl 4 - 
2KC1). Platinic chloride having been stated to be a test for potas- 
sium and ammonium salts, the reader is prepared to find that potas- 
sium and ammonium salts are tests for platinic salts. The double 
sodium compound (PtCl 4 2NaCl) is soluble in water. 

Collect the precipitate, dry, and heat in a small crucible ; 
it is decomposed, and metal, in the finely divided state of 
spongy platinum, remains. 

3(PtCl 4 2NH 4 Cl) = Pt 3 + 2NH 4 C1 + 16HC1 + 2N 2 . 

Heat decomposes the potassium salt into Pt + 2KC1 + Cl 4 , the 
chlorine escaping and the chloride of potassium remaining with the 
platinum. 

In working up the platinum residues of laboratory operations, the 
mixture should be dried, burnt, boiled successively with hydrochloric 
acid, water, nitric acid, water, then dissolved in aqua regia, excess 
of acid removed by evaporation, chloride of ammonium added, the 
precipitate washed with water, dried, ignited, and the resulting 
spongy platinum retained or converted into perchloride for use as a 
reagent for alkali metals. It is by this process that the native plat- 
inum is treated to free it from the rare metals palladium, rhodium, 
osmium, ruthenium, and iridium. The spongy platinum is converted 
into the massive condition by a refinement on the blacksmith's pro- 
cess of welding (German wellen, to join), or by fusing in a flame of 
pure oxygen and hydrogen gases, the oxyhydrogen blowpipe. 

Occlusion by Spongy Platinum. — Spongy platinum has great 
power of occlusion. A small piece held in a jet of hydrogen causes 



CADMIUM. 247 

ignition of the gas, owing to the close approximation of particles of 
oxygen (from the air) and hydrogen. Dobereiner's lamp is con- 
structed on this principle — the apparatus being essentially a vessel 
in which hydrogen is generated by the action of diluted sulphuric 
acid on zinc, and a cage for holding the spongy platinum. 

CADMIUM. 

Symbol Cd. Atomic weight 1 1 1.8. 

In most of its chemical relations cadmium {Cadmium, U. S. P.) 
resembles zinc. In nature it occurs chiefly as an occasional con- 
stituent of the ores of that metal. In distilling zinc containing 
cadmium, the latter, being the more volatile, passes over first. In 
analytical operations, cadmium, unlike zinc, comes down among the 
metals precipitated by sulphuretted hydrogen ; that is, its sulphide 
is insoluble in dilute hydrochloric acid, while sulphide of zinc is 
soluble. It is a white malleable metal nearly as volatile as mercury. 
Sp. gr. 8.7. 

Beyond the occasional employment of the sulphide as a pigment 
(Jaime brillant), and the iodide in photography, cadmium and its 
salts are but little used. The atom of cadmium is bivalent (Cd"). 

Reactions. 

Iodide of Cadmium. 

First Synthetical Reaction. — Digest together in a flask me- 
tallic cadmium, water, and iodine until the color of the iodine 
disappears ; solution of iodide of cadmium (Cdl 2 ) remains. 
Pearly micaceous crystals may be obtained on evaporating 
the solution. 

This salt is employed, with other iodides, in iodizing collodium 
for photographic purposes. It melts when heated, and is soluble 
in water o^ spirit, the solution reddening litmus-paper. 

Sulphate of Cadmium. 

Second Synthetical Reaction. — Dissolve cadmium in nitric 
acid ; pour the resulting solution of nitrate of cadmium 
(Cd2N0 3 ) into a solution of carbonate of sodium ; dissolve the 
precipitate of carbonate of cadmium (CdC0 8 ) in dilute sul- 
phuric acid, separate and crystallize. Sulphate oi' cadmium 
(CdS0 4 ) is a white crystalline salt soluble in water. 

First Analytical Reaction. — Through solution of a cadmium 
salt (Cdl 2 or CdCl 2 ) pass sulphuretted hydrogen ; a yellow 
precipitate of sulphide of cadmium (CdS) falls, resembling in 
appearance arsenious, arsenic, and stannic sulphides. Add 
sulphydrate of ammonium; the precipitate, unlike the sul- 
phides just mentioned, does not dissolve. 



248 RARER METALLIC RADICALS. 

Sulphides of cadmium and copper may be separated by solution 
of cyanide of potasssium, in "which sulphide of copper is soluble and 
sulphide of cadmium insoluble. 

Second Analytical Reaction. — To a cadmium solution add 
solution of potash ; white hydrate of cadmium (Cd2H0) is 
precipitated, insoluble in excess of the potash. 

Hydrate of zinc (Zn2HO), precipitated under similar circum- 
stances, is soluble in solution of potash ; the filtrate from the hy- 
drate of cadmium may therefore be tested for any zinc occurring as 
an impurity by applying the appropriate reagent — sulphydrate of 
ammonium. 

Before the bloupipe-Jlame, on charcoal, cadmium salts give 
a brown deposit of oxide of cadmium (CdO). 

BISMUTH. 

Symbol Bi. Atomic weight 209. 

Source. — Bismuth occurs in the metallic state in nature. It is 
freed from adherent quartz, etc. by simply heating, when the metal 
melts, runs off, and is collected in appropriate vessels (Bismuthum, 
B. P.). It is also met with in combination with other elements. 
Bismuth is grayish-white. Avith a distinct pinkish tinge. 

Purification. — Arsenium may be removed from melted bismuth by 
a rod of iron, arsenide of iron rising to the surface of the mass ; an- 
timony, by stirring in some oxide of bismuth, when oxide of anti- 
mony separates. Other metals in bismuth, especially copper, are 
converted into sulphides, while bismuth is not affected on fusing the 
crude metal with about 5 per cent, of cyanide of potassium and 2 per 
cent, of sulphur, the whole being well stirred for a quarter of an 
hour with a clay rod (stem of a tobacco-pipe). On pouring off the 
metal from the flux, and melting and stirring it with about 5 per 
cent, of a mixture of the carbonates of potassium and sodium, sul- 
phur and traces of the impurities are removed and the metal obtained 
pure (Bismuthum Purijicatum, B. P.). — Tamm. 

Uses. — Beyond the employment of some of its compounds in medi- 
cine, bismuth is but little used. Melted bismuth expands consider- 
ably on solidif}-ing, and hence is valuable in taking sharp impres- 
sions of dies. It is a constituent of some kinds of type-metal and of 
pewter-solder. 

The position of bismuth among the metals is close to that of ar- 
senicum and antimony. Its atom is rarely quinquivalent (Bi v ), but 
in most compounds trivalent (Bi 7 "). 

Reactions hating (a) Synthetical and (l) Analytical 

Interest. 

(«) Reactions having Synthetical Interest. 

Nitrate of Bismuth. 

First Synthetical Reaction. — To a few drops of nitric acid 



btsmuth. 249 

and an equal quantity of water in a test-tube add a little pow- 
dered bismuth, heating the mixture if necessary; nitric oxide 
(NO) escapes, and solution of nitrate of bismuth (Bi3N0 3 ) 
results. 

Bi 2 -j- 8HNO3 == 2(Bi3N0 3 ) + 2NO + 4H 2 

Bismuth. Nitric acid. Nitrate of bismuth. Nitric oxide. Water. 

The solution evaporated gives crystals (Bi3N0 3 ,5H 2 0), any arsen- 
icum which the bismuth might contain remaining in the mother- 
liquor. 

To make nitrate of bismuth and other salts on a larger scale, 2 
ounces of the metal, in small fragments, are gradually added to a 
mixture of 4 fluidounces of nitric acid and 3 of water, and, when 
effervescence (due to escape of nitric oxide) has ceased, the mixture 
is heated for ten minutes, poured off from any insoluble matter, 
evaporated to 2 fluidounces to remove excess of acid, and then either 
set aside for crystals to form, or poured into a half gallon of water 
to form the oxynitrate of bismuth, or into a solution of 6 ounces of 
carbonate of ammonium in a quart of water to form the oxy carbo- 
nate, as described in the following reactions. The precipitates should 
be washed with cold water and dried at a temperature not exceeding 
150° F. Exposed in the moist state to 212° for any length of time, 
they undergo slight decomposition. 

Subnitrate or Oxynitrate of Bismuth. 

Second Synthetical Reaction. — Pour some of the above solu- 
tion of nitrate into a considerable quantity of water ; decompo- 
sition occurs, and oxynitrate of bismuth (BiON0 3 ) in a hydrous 
state (BiON0 3 ,H 2 0) (Bismuthi Subnitras, U. S. P.) is precipi- 
tated : — 

Bi3N0 3 + H 2 = BiON0 3 + 2HN0 3 

Nitrate of Water. Oxynitrate of Nitric acid, 

bismuth. bismuth. 

Filter, and test the filtrate for bismuth by adding excess of 
carbonate of sodium ; a precipitate shows that some bismuth 
remains in solution. The following equation, therefore, prob- 
ably more nearly represents the decomposition : — 

5(Bi3N0 3 ) -f- 8II 2 = 4(BiON0 3 ,H 2 0) + Bi3N0 3 ;8HN0 3 

Nitrate of Water. Oxynitrate of Nitrate of bismuth 

bismuth. bismuth. in acid. 

Decomposition of nitrate of bismuth by water is the process oi' 
the Pharmacopoeia for the preparation of oxynitrate or "subnitrate" 
of bismuth for use in medicine. For this purpose the original metal 
must contain no arsenieum. In manufacturing the compound, 
therefore, before pouring the solution of nitrate into water, the 
li<iuiil should be tested for arsenieum by one oi' the hydrogen bests : 
if that element be present, the solution must be evaporated and only 



250 RARER METALLIC RADICALS. 

the deposited crystals be used in the preparation of the oxynitrate. 
For on pouring an arsenical solution of nitrate of bismuth into 
water, the arsenicum is not wholly removed in the supernatant 
liquid, unless the oxynitrate be redissolved and reprecipitated sev- 
eral times, according to the amount of arsenicum present. 

Subnitrate of bismuth is gradually decomposed by solution of 
alkaline carbonates ; also by the bicarbonates, with production of 
carbonic acid gas, oxycarbonate of bismuth and nitrate of the alkali- 
metals being formed. It is used as a cosmetic under the name of 
Pearl-ichite (Blanc de Perle). 

Oxysalts of Bismuth — It will be noticed that the formula for sub- 
nitrate of bismuth (BiN0 4 ) does not accord with that of other 
nitrates, the characteristic elements of which are N0 3 . Analogy 
would seem to indicate, however, that the fourth atom of oxygen 
has different functions from the three in the N0 3 ; for on pouring 
solution of chloride of bismuth (BiCl 3 ) into water, oxychloride is 
produced (BiOCl) (a white powder used as a cosmetic, also in 
enamels, and in some varieties of sealing-wax). The bromide 
(BiBr 3 ) and iodide (Bil 3 ) similarly treated yield oxybromide (BiOBr) 
and oxyiodide (BiOI). The subnitrate (BiN0 4 ) is, therefore, prob- 
ably an analogous compound, an oxynitrate (BiON0 3 ). The sulphate 
(Bi 2 3S0 4 ) also decomposes when placed in water, giving what may be 
termed an oxysulphate (Bi 2 0. 2 S0 4 ). 

It is difficult to prove whether or not the water in the " sub- 
nitrate " or hydrous oxynitrate of bismuth (BiON0 3 ,H 2 0) is an inte- 
gral part of the salt. If it is, the compound is simply the hydrato- 
nitrate (BiN0 3 2HO) of bismuth. 

Oxide of Bismuth. 

Third Synthetical Reaction. — Boil subnitrate of bismuth 
with solution of soda for a few minutes ; it is converted into 
yellowish oxide of bismuth (Bi 2 3 ) (Bismuthi Oxidum, B. P.). 

+ H 2 



2BiON0 3 


+ 


2NaHO = 


= Bi 2 O s 


+ 


2NaNO, 


Oxynitrate of 




Hydrate of 


Oxide of 




Nitrate of 


bismuth. 




sodium. 


bismuth. 




sodium. 



Subcarbonate or Oxycarbonate of Bismuth. 

Fourth Synthetical Reaction. — To solution of nitrate of bis- 
muth add carbonate of ammonium or carbonate of sodium ; a 
white precipitate of hydrous oxycarbonate (2Bi 2 2 C0 3 ,H 2 0) 
(Bismuthi Subcarbonas, U. S. P.) falls. 

2(Bi3N0 3 ) -f Na 2 C0 3 = 6NaN0 3 + Bi 2 2 C0 3 + 2C0 2 

Nitrate of Carbonate of Nitrate of Oxycarbonate Carbonic 

bismuth. sodium. sodium. of bismuth. acid gas. 

This compound may be regarded as similar in constitution to the 
oxysalts just described. In Bi 2 C0 3 one scarcely recognizes the cha- 
racteristic elements of carbonates ; but considering the preparation 
to be an oxycarbonate (Bi 2 2 C0 3 ), its relations to carbonates and 
oxides are evident. These subsalts may all be viewed as normal 



BISMUTH 251 

bismuth salts in which an atom of oxygen displaces an equivalent 
proportion of other acidulous atoms or radicals : — 

Chloride .... Bi3Cl Oxychloride . . BiOCl 

Bromide .... Bi3Br Oxybromide . . BiOBr 

Iodide Bi3I Oxyiodide . . BiOI 

Nitrate Bi3N0 3 Oxynitrate . . BiON0 3 

Sulphate .... Bi 2 3S0 4 Oxysulphate . . Bi 2 2 S0 4 

Carbonate (unknown) Bi 2 3C0 3 Oxycarbonate . Bi 2 2 C0 3 

They may be viewed, in short, as salts in process of conversion to 
oxide ; continue the substitution a little further, and each yields 
oxide of bismuth (Bi 2 3 ). They have also been considered to be 
salts of a hypothetical univalent radical, bismuthyl (BiO). 

Citrate of Bismuth. 

Fifth Synthetical Reaction. — Heat ten parts of oxynitrate of 
bismuth, seven of citric acid crystals, and thirty to forty of 
water together for a few minutes, until a drop of the mixture 
forms a clear solution with ammonia-water. Dilute the crystal- 
line mass with eight to ten times its volume of water, and set 
aside for a short time to let the citrate deposit ; decant the 
clear liquid. Wash the crystalline sediment three or four times 
in a similar manner, drain and dry, either on a water-bath or 
by mere exposure. The yield is 13f parts, showing that the 
salt is anhydrous, and that its formula is BiC 6 H 5 7 (Rother). 
This is the Bismuthi Citras, U. S. P. 

Sixth Synthetical Reaction. — Mix citrate of bismuth with 
water, add sufficient solution of ammonia to form a clear liquid, 
filter if necessary, evaporate to a syrupy consistence, spread on 
glass plates, and dry slowly until pearly scales are obtained. 
This is the Bismuthi et Ammouii Citras, U. S. P. 

(b) Reactions having Analytical Interest ( Tests). 

First Analytical Reaction. — Through solution of a bismuth 
salt (a slightly acid solution of nitrate, for example) pass sul- 
phuretted hydrogen ; a black precipitate of sulphide of bismuth 
(Bi 2 S 3 ) falls. Add ammonia (to neutralize acid), and then sulphy- 
drate of ammonium ; the precipitate, unlike As,S 3 and Sb 2 8 ;i , is 
insoluble. 

Second Analytical Reaction. — Concentrate almost any acid 
solution of a bismuth salt and pour into water; a white salt is 
precipitated. 

This reaction is characteristic of bismuth salts: it has already 
been amply explained. The precipitate is distinguished from one 
formed by antimony under similar circumstances by being insol- 
uble in solution of tartaric acid. 



252 RARER METALLIC RADICALS. 

Third Analytical Reaction — To a solution of a bismuth salt 
add an alkali ; hydrate of bismuth (Bi3HO) is precipitated, in- 
soluble in excess. 

Fourth Analytical Reaction. — A small quantity of the fol- 
lowing reagent, including both supernatant liquid and precip- 
itated scales, is transferred to a test-tube and gradually heated 
until solution takes place. Any liquid containing or supposed 
to contain bismuth is then added, and the whole allowed to cool. 
The separated scales will show a distinct change in color to 
dark orange or crimson according to the quantity of bismuth 
present. 

The reagent may be prepared by adding to a boiling solution of 
acetate of lead (half a grain to the ounce) a few drops of acetic acid 
and solution of iodide of potassium in considerable excess. On cool- ' 
ing, iodide of lead is deposited in the characteristic scales. 

Test for Phosphate of Calcium in Bismuth Salts. — Dissolve the 
powder in nitric acid ; add about twice its weight of citric acid, and 
sufficient ammonia to give decided alkalinity ; then boil, keeping the 
mixture faintly alkaline with ammonia : bismuth remains in solution 
and phosphate of calcium is precipitated. 



The reader is again advised to trace out the exact nature of each 
of the foregoing reactions, chiefly by aid of equations or diagrams. 



QUESTIONS AND EXERCISES. 

343. Enumerate the fifteen metals, salts of which are frequently 
employed in pharmacy. 

344. Mention the twelve rarer metals interesting to pharmacists. 

345. Name the sources and official compounds of lithium. 

346. Show by an equation the formation of Citrate of Lithium. 

347. What is the strength of Liquor Lithiaz Effervescens ? 

348. On what chemical hypothesis are lithium compounds admin- 
istered to gouty patients ? 

349. Describe the relation of lithium to other metals. 

350. What is the chief test for lithium ? 

351. Write a paragraph on strontium, its natural compounds, 
chemical relations, technical applications, and tests. 

352. What are the formulae and properties of oxalate of cerium ? 

353. Name the commonest ores of manganese, and give an equa- 
tion descriptive of its reaction with hydrochloric acid. 

354. Explain the formation of permanganate of potassium, em- 
ploying diagrams or equations. 

355. How do the manganates of potassium act as disinfectants? 

356. What are the chief tests for manganese ? 

357. What are the chief uses of the compounds of cobalt? 



QUESTIONS AND EXERCISES. 253 

358. How is cobalt analytically distinguished from nickel? 

359. Mention applications of nickel in the arts. 

360. What is the general color of nickel salts ? 

361. State the method of making red chromate of potassium. 

362. Give the formulae of red and yellow chromates of potassium. 

363. How is red chromate of potassium obtained? 

364. Describe the action of sulphuretted hydrogen on acidified 
solutions of chromates. 

365. What is the formula of chrome alum ? 

366. Mention the chief tests for chromium and chromates. 

367. How would you detect iron, chromium, and aluminium in a 
solution ? 

368. Define tinstone, stream-tin, block-tin, grain-tin, tin-plate. 

369. Describe the position of tin in relation to other metals. 

370. How does stannic acid differ from metastannic acid? 

371. State the applications of tin in the arts. 

372. Mention the chief tests for stannous and stannic salts. 

373. Name the best antidote in cases of poisoning by tin solution. 

374. How is gold-dust separated from the earthy matter with 
which it is naturally associated? 

375. How much pure gold do English coin and jeweller's gold 
contain ? 

376. State the average thickness of gold-leaf. 

377. What is the weight of a sovereign? 

378. Explain the term "fineness" as applied to gold. 

379. What effect is produced on gold by hydrochloric, nitric, and 
nitro-hydrochloric acids respectively ? 

380. How may metallic gold be precipitated from solution? 

381. How is Purple of Cassius prepared? 

382. Whence is platinum obtained? 

383. Why are platinum utensils peculiarly adapted for use in 
chemical laboratories ? 

384. How is perchloride of platinum prepared? 

385. Name the chief tests for platinum. 

386. What is " platinum black " ? 

387. Describe an experiment demonstrative of the large amount 
of attraction for gases possessed by metallic platinum. 

388. How is " spongy platinum ' ; produced? 

389. By what process may platinum be recovered from residues? 

390. What is occlusion in chemistry? 

391. In what condition does cadmium occur in nature? 

392. By what process may iodide of cadmium be prepared? 

393. Mention the chief test for cadmium. 

394. Distinguish cadmium sulphide from other yellow sulphides. 

395. How is cadmium separated from zinc? 

396. How does bismuth occur in nature ? 

397. What is the quantivalence of bismuth ? 

398. Write down equations descriptive of the actions of nitric acid 
on bismuth, and water on nitrate of bismuth. 

399. How may arsenicum be excluded from bismuth salts? 

400. Give a diagram of the process for Carbonate of Bismuth. 



254 RARER METALLIC RADICALS. 

401. Write formulae showing the accordance in composition of the 
official Subnitrate and Carbonate with the other salts of Bismuth, and 
with ordinary Nitrates and Carbonates. 

402. How is Bismuthi et Ammonii Citras prepared ? 

403. What are the tests for Bismuth ? 



Practical Analysis. 

Bismuth is the last of the metals whose synthetical or analytical 
relations are of general interest. The position of the rarer among 
the common metals, and the influence which either has on the other 
during the manipulations of analysis, will now be considered. These 
objects will be best accomplished, and a more intimate acquaintance 
with all the metals be obtained, by analyzing, or studying the meth- 
ods of analyzing, solutions containing one or more metallic salts. 

Of the following Tables, the first (1) includes directions for the 
analysis of an aqueous or only slightly acid solution, containing but 
one salt of any of the metals hitherto considered. Here the color 
of the precipitate or precipitates afforded by a metal under given 
circumstances must largely be relied on in attempting the detection 
of the various elements. 

The long Table (2) is intended as a chart for the analysis of solu- 
tions containing salts of more than one of the common and rarer 
metals. • It is a compilation from the foregoing reactions — an exten- 
sion of the scheme for the analysis of salts of the ordinary metals. 
It often may be altered or varied in arrangement to suit the require- 
ments of the analyst. 

That on p. 256 is a mere outline of the other two Tables. It gives 
the position of the metals in relation to each other, and will much 
aid the memory in recollecting that relation. 

The analysis of solutions containing only one metal will, as already 
stated, serve to impress the memory with the characteristic tests for 
the various metals and other radicals, and familiarize the mind with 
chemical principles. Medical and junior pharmaceutical students 
seldom have time to go further than this. More thorough analytical 
and general chemical knowledge is only acquired by working on such 
mixtures of bodies as are met with in actual practice, beginning with 
solutions which may contain any or all of the members of a group 
(see previous pages), then examining solutions containing more than 
one group, and finally analyzing liquids in which are dissolved 
several salts of any of the common or rarer metals. 

The Author cannot too strongly recommend students thoroughly 
to master the art of analysis, not only on account of its direct value, 
but because its practice enables the learner rapidly and soundly to 
acquire a good knowledge of chemistry, and greatly to improve his 
general mental faculties. 



\_To face page 255. 
'aqueous or only slightly acid solution of ordinary 

EREST. 



Ba Ca Sr Mg L 


K Na NH,. 


Filtrate 




N T i Al Fe Cr Ba Ca Sr Mg L K Na NH 4 


t Cl, KE3HO, NH 4 HS, warm gently and filter. 




Filtrate 


Cr. 


Ba Ca Sr Mg L K Na NH 4 


7 drops of HNO3, 
er. 


Add (NH 4 ) 2 C0 3 , warm, filter. 


Filtrate 


Precipitate Filtrate 
Ba Sr Ca. 1 Mg L K Na NH 4 . 
Collect, wash, dissolve in Add (NH 4 ) 2 HAs0 4 , stir, filter. 


Mn Co Ni. 


HC 9 H 3 9 , pass H 2 S, 


filter. 


HC2H3O9, add excess of 
K 2 Cr0 4 , filter. 








Precipitate 


Ppt. 


Filtrate 


Pot. 


Filtrate 


Zn Co Ni. 


Ba. 


Sr Ca. 


M ff . 


L K Na NH 4 


with HC1 and a little 


Yellow. 


Add dilute H 2 S0 4 , 




Evaporate to small 


3 ; add KHO, filter. 




let stand, filter. 




bulk. AddNH 4 HO. 




Precipitate 


Ppt. 


Filt. 


]£ 


Filtrate 




Co Ni. 




Sr. 


Ca. 




K Na NH 4 . 


S. 


Dissolve in HC1, 






Add 






Evaporate, 




and proceed as 

directed on page 

234. 






NH 4 HO and 

(NH 4 ) 2 C 2 4 . 
White ppt. 






ignite, dissolve. 
K by PtCi 4 , 
Na by name. 

NH 4 in original 
solution. 


L 




See also p. 258. 





ANALYTICAL TABLES. 



255 






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M P S- 1— I 






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B ' o B "-j cs 






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old-out is being digitized, and 
be inserted at a future date. 



256 GENERAL AND SPECIAL MEMORANDA. 

3. OUTLINE OF THE ANNEXED ANALYTICAL TABLES. 



HC1 


H 2 S 


NH 4 HS 


(NH 4 ) 2 C0 3 


(NH 4 ) a HAs0 4 




Hg 


Cd 




Zn 


C 


Ba 


Mg 


K 


(as mercurous 














salt) 


Cu 


X 




^5 








Pb 




w 


Mn* 


.5 


Sr 




Na 


(partially) 


Hg 


y 




.% 










(as mer- 


'l 


Co 


| 


Ca 




NH 4 




curic 
















salt) 


| 




| 








Ag 


Pb 

(entirely) 

Bi , 

As 1 

(as arse- 

nious or 

arsenic 

salt) 

Sb 


y< 


Ni 

Al 1 
Fe 


c 

ft 






I, 




Sn 


-.2 


Cr . 


ft 










(as stan- t 


~ 














nous or 


P 














stannic 
















salt) 




* See page 
229. 












Aii 
















Pt 















The laboratory student should practise the examination of aque- 
ous solutions of salts of the above metals until able to analyze with 
facility and acuracy. 



General and Special Memoranda relating to the 
preceding Analytical Tables. 

General Memoranda. 

These charts are constructed for the analysis of salts more or less 

soluble in water. The student has still to learn how substances 

insoluble in water are to be brought into a state of solution: but, 
once dissolved, their analysis is effected by the same scheme as that 
just given. The Tables, especially the second (No. 2), may there- 
fore be regarded as fairly representing the method by which metallic 



ANALYTICAL MEMORANDA. 257 

constituents of chemical substances are separated from each other 

and recognized. The methods of isolation of the complementary 

constituent of the salt (the reactions of non-metals and acidulous 
radicals) will form the next object of practical study. 

The general memoranda given in connection with the first Table 
(p. 219) are equally applicable to the extended second Table, and 
should again be carefully read through. 

Special Memoranda. 

The hydrochloric-acid precipitate may at first include some anti- 
mony and bismuth as oxy chlorides, readily dissolved, however, by 
excess of acid. If either of these elements be present, the wash- 
ings of the precipitate will probably be milky 5 in that case add a 
few drops of hydrochloric acid, which will clear the liquid and make 
way for the application of the test for lead. 

The sulphuretted-hydrogen precipitate may be white, in which 
case it is nothing but sulphur ; for, as already indicated, ferric salts 
are reduced to ferrous, and chromates to the lower salts of chromium 
by sulphuretted hydrogen, sulphur being deposited : — 

2Fe 2 Cl 6 + 2H 2 S = 4FeCl 2 + 4HC1 + S 2 ; 
4H 2 Cr0 4 + 6H 2 S + 12HC1 = 2Cr 2 Cl 6 + 16H 2 -f 3S 2 . 

But the precipitate may also be colored, or even white when only 
lead or mercury is present, through an insufficiency of sulphuretted 
hydrogen having produced a peculiar oxysulphide or hydrato-sul- 
phide. The gas should be passed through the liquid until, even 
after well shaking, it smells strongly of sulphuretted hydrogen. 

The portion of the sulphuretted-hydrogen precipitate dissolved 
by sulphydrate of ammonium may include a trace of copper, sul- 
phide of copper being not altogether insoluble in sulphydrate of 

ammonium. On adding hydrochloric acid to the sulphydratc-of- 

ammonium solution, a white precipitate of sulphur only may be 
produced, the sulphydrate of ammonium nearly always containing 

free sulphur. Strong hydrochloric acid does not readily dissolve 

small quantities of sulphide of antimony out of much sulphide of 
arsenicuin 5 and, on the other hand, the strong hydrochloric ac id- 
takes into solution a small quantity of sulphide of arsenicum if 
much sulphide of antimony is present. The precipitate or the 
original solution should therefore be examined by the other (hydro- 
gen) tests for these elements if doubt exists concerning the presence 
or absence of either. Tin remains in the hydrogen-bottle in the 
metallic state, deposited as a black powder on the zinc used in the 
experiment. The contents of the bottle are turned out into a dish, 
ebullition continued until evolution of hydrogen ceases, and the 
zinc is taken up by the excess of sulphuric acid employed : any tin 
is then filtered out, washed, dissolved in a few drops o( hydro- 
chloric acid, and the liquid tested for tin by the usual reagents. 

-Tin may be detected in the mixed sulphides oi' tin, arsenicum. 

and antimony by the blowpipe reaction (vide Index). 

The portion of (he sulphuretted-hydrogen precipitate not dis- 
solved by the sulphydrate of ammonium may leave a yellow semi- 



258 SPECIAL MEMORANDA. 

fused globule of sulphur on boiling with nitric acid. This globule 
may be black, not only from presence of mercuric sulphide, but also 
from inclosed particles of other sulphides protected by the sulphur 
from the action of the acid. It may also contain sulphate of lead, 
produced by the action of nitric acid on sulphide of lead. In cases 
of doubt the mass must be removed from the liquid, boiled with 
nitric acid till dissolved, the solution evaporated to remove excess of 
acid, and the residue examined 5 but usually it may be disregarded. 

Before testing for bismuth, any considerable excess of acid 

should be removed by evaporation, and the residual liquid should 
be freely diluted. If no precipitate (oxynitrate of bismuth) appear, 
chloride-of-ammonium solution may be added, oxy chloride of bis- 
muth more readily forming than even oxynitrate. Or any nitric 

acid or sulphuric acid having been neutralized by ammonia, hydro- 
chloric acid is added, and then iodide of potassium •, a rich orange 
color results if bismuth be present. Bismuth may also be de- 
tected in the mixed precipitated hydrates of bismuth and lead, ob- 
tained in the ordinary course of analysis, by dissolving a portion of 
the precipitate in acetic acid and adding the liquid to the hot iodide 
of lead solution mentioned in the reactions for bismuth (p. 292). 

In testing for lead by sulphuric acid the liquid should be diluted 

and set aside for some time. 

Mercury may also be isolated by digesting the sulphuretted-hydro- 
gen precipitate in sulphydrate of sodium instead of sulphydrate of 
.ammonium. The sulphides of arsenicum, antimony, tin, and mer- 
cury are thus dissolved out. The mixture is then filtered, excess of 
hydrochloric acid added to it, and the precipitated sulphides collected 
on a filter, washed, and digested in sulphydrate of ammonium ; sul- 
phide of mercury remains insoluble, while the sulphides of arseni- 
cum, antimony, and tin are dissolved. By this method copper also 
appears in its right place only, sulphide of copper being quite 
insoluble in sulph} r drate of sodium. The other metals are then 
separated in the usual way. 

The sulphydrate-of-ammonium precipitate may, if the original 
solution was acid, contain Phosphates, Oxalates, Silicates, and Bo- 
rates of Barium, Calcium, and Magnesium. These will subsequently 
come out with the iron, and, being white, give the iron precipitate a 
light-colored appearance ; their examination must be conducted sep- 
arately, by a method described subsequently in connection with the 
treatment of substances insoluble in water. The precipitates con- 
taining aluminium, iron, and chromium hydrates often contain some 
manganese. This manganese may be detected by washing the hy- 
drates to remove all traces of chlorides, boiling with nitric acid, 
adding either puce-colored oxide of lead or red lead, and setting the 
vessel aside. If manganese be present a red or purple liquid is pro- 
duced. Sulphide of nickel is not easily removed by filtration (vide 

p. 234) until most of the excess of sulphydrate of ammonium has 
been dissipated by prolonged ebullition. 

TJie carbonate-of -ammonium precipitate may not contain the 
whole of the barium, strontium, and calcium in the mixture, unless 
free ammonia be present ; for the carbonates of those metals are 



QUESTIONS AND EXERCISES. 259 

soluble in water charged with carbonic acid. If, therefore, the liquid 
is not distinctly ammoniacal, solution of ammonia should be added. 

Neither carbonate nor hydrate of ammonium wholly precipitates 

magnesian salts ; and, as a partial precipitation is undesirable, a sol- 
vent, in the form of an alkaline salt (chloride of ammonium), if not 

already in the liquid, should be added. In the chart opposite p. 

254 strontium is ordered to be separated from calcium by adding to 
the acetic solution diluted sulphuric acid. The latter, unless ex- 
tremely dilute, may precipitate calcium. Any such loss of calcium 
is in itself of little consequence, because enough sulphate of calcium 
remains in the nitrate to afford a calcium reaction when ammonia 
and oxalate of ammonium are subsequently added. But the cal- 
cium precipitated by the sulphuric acid may be wrongly set down as 
strontium. Therefore test a little of the acetic solution for strontium 
by an aqueous solution of sulphate of calcium, when, if no precipi- 
tate falls after setting aside for several minutes, strontium may be 
regarded as absent. If a precipitate occurs strontium is present; 
the rest of the acetic solution is then tested for calcium as directed; 
in the chart, the final testing by oxalate of ammonium being, of 
course, preceded by the addition of ammonia. 

Lithium. — The search for lithium may usually be omitted. Should 
a precipitate, supposed to be due to lithium, be obtained, it must be 
tested in a flame (= scarlet tint), as a little magnesium not unfre- 
quently shows itself under similar circumstances. 

Spectral Analysis. — If present only in minute proportions, the 
lithium may also remain with the alkalies ; it can then only be de- 
tected by physical analysis (by a prism) of the light emitted from a 
tinged flame — by, in short, an instrument termed a spectroscope. 
Such a method of examination is called spectral analysis, a subject 
of much interest and of no great difficulty, but scarcely within the 
range of Pharmaceutical Chemistry; it will be briefly described in 
connection with the methods of analyzing solid substances. 



QUESTIONS AND EXERCISES. 

404. Describe a general method of analysis by which the metal of 
a single salt in a solution could be quickly detected. 

405. Give illustrations of black, white, light pink, yellow, and 
orange sulphides. 

400. Mention the group-tests generally employed in analysis. 

407. Under what circumstances may a hydrochloric precipitate 
contain antimony or bismuth? 

408. If a sulphuretted-hydrogen precipitate is white, what suit- 
stances are indicated? 

409. Give processes for the qualitative analysis of liquids contain- 
ing the following substances : — a. Arsenicum and Cadmium; /'. l>is- 
muth and Antimony; c. Ferrous and Ferric salts; (/. Aluminium, 
Iron, and Chromium; e. Arsenicum, Antimony, and Tin ; /'. bead 
and Strontium ; g. Iron, Sodium, and Arsenicum 5 h. Mercury, Man- 
ganese, and Magnesium; /. Zinc, Manganese, Nickel, and Cobalt) 
j. Barium, Strontium, and Calcium. 



2G0 THE ACIDULOUS RADICALS. 



THE ACIDULOUS KADICALS. 

Introduction. — The twenty-seven radicals which have up to this 
point mainly occupied attention are (admitting ammonium, NH 4 ) 
metals ; and they have been almost exclusively studied not in the 
free state, but in the condition in which they exist in salts. More- 
over, these metals have been treated as if they formed the more im- 
portant constituent, the stronger half, the foundation or base of salts. 
Attention has been continuously directed to the metallic or basylous 
side of salts. And indeed there is still one more basylous radical 
which must be mentioned, though it is usually supposed to play only 
a subordinate part in medicine — Hydrogen. Unlike the salts of 
most metals, those of hydrogen (the so-called acids) are never, in 
medicine or the arts generally, professedly used for the sake of their 
hydrogen, but always for the other half of the salt, the acidulous 
side. And it is not for their basylous radical that these hydrogen 
salts are now commended to notice,* but in order to study, under the 
most favorable circumstances, those acidulous groupings which have 
continually presented themselves in operations on salts, but which 
were for the time of secondary importance. These acidulous radi- 
cals may now be treated as the primary object of attention; and 
there is no better way of doing so than in operating on their com- 
pounds with hydrogen, the apparently inferior medicinal importance 
of which element, as compared with potassium, iron, and other basyl- 
ous radicals, will serve to give the desired prominence to the acid- 
ulous radicals in question . f 

Common Acids. — These salts of hydrogen (hydrogen easily dis- 
placeable, or in certain cases, in part, by ordinary metals) are the 

* It must not be forgotten that the commonest salt of any radical 
whatsoever is a salt of hydrogen, the oxide of hydrogen (H 2 0), or 
hydrate of hydrogen (HHO), wider. In the reactions already per- 
formed the value of this compound has been constantly recognized, 
both for its hydrogen and for its oxygen, but most of all as the vehicle 
or medium by which nearly all other atoms are enabled to come into 
that contact with each other without which their existence would be 
almost useless ; for some atoms are like some animals — out of water 
they are as inactive as fishes. It is true that both fishes and salts have 
usually to be removed from water to be utilized by man ; but before 
they can be assimilated, either as food or as medicine, they must again 
seek the agency of water in becoming dissolved. 

f Actually, it is as difficult to determine the relative importance of 
the different atoms or groups of atoms in a molecule as of the different 
parts or members of an animal or vegetable, the different units or socie- 
ties in a community, the different planets or solar systems of the uni- 
verse; nay, the different pieces or parts of an engine or the pigments 
or portions of a picture : /' union fait la force. 



SALTS OF ACIDULOUS RADICALS. 261 

ordinary sharp, sour bodies termed acids (from the Latin root acies, 
an edge). The following Table includes the formulae and usual 
names of the most important ; others will be noticed subsequently. 
A few of those mentioned are unstable or somewhat rare ; in such 
cases a common metallic salt containing the acidulous radical may 
be used for reactions. 



HC1 


hydrochloric acid. 


HBr 


hydrobromic acid. 


HI 


hydriodic acid. 


HCN (HCy) 


hydrocyanic acid. 


HN0 3 


nitric acid. 


HCIO3 


chloric acid. 


HC 2 H 3 2 


acetic acid.' 55 ' 


H 2 S 


hydrosulphuric acicl.f 


H 2 S0 3 


sulphurous acid. 


H 2 S0 4 


sulphuric acid. 


H 2 C0 3 ? 


carbonic acid. 


H 2 C 2 4 


oxalic acid. 


II,CJT 4 6 


tartaric acid. 


H 3 C 6 H 5 7 


citric acid. 


H 3 P0 4 


phosphoric acid. 


H 3 B0 3 


boracic acid. 



The old names are here retained for these acids, but, in studying 
their chemistry and chemical relations to other salts, they are use- 
fully spoken of by such more purely chemical names as (for hydro- 
chloric acid) chloride of hydrogen, (for nitric acid) nitrate of hydro- 
gen, and so on — sulphate of hydrogen, tartrate of hydrogen, phos- 
phate of hydrogen. 

A prominent point of difference will at once be noticed between 
the basylous radicals met with up to the present time and the acidu- 
lous groupings included in the above tabular list. The former are 
nearly all elements, ammonium only being a compound ; the latter 
are mostly compounds, chlorine, bromine, iodine, and sulphur being 
the only elements. This difference will not, however, be so appar- 
ent when the chemistry of alcohols, ethers, and such bodies has 
been mastered, for they may be regarded as salts of compound 
basylous radicals. 



* The hydrogen on the acidulous side must not be confounded with 
the basylous hydrogen in all these hydrogen salts or acids; the two 
perform entirely different functions. Hydrogen in the acidulous por- 
tion is like the hydrogen in the basylous radical ammonium : it has 
combined with other atoms to form a group which plays more or less 
the part of an elementary radical, and to which a single symbol is not 
unfrequently applied (Am; (V, A, O, T, C, etc.). Cobalt, chromium, 
iron, platinum, etc., resemble hydrogen in this respect in often uniting 
with other atoms to form definite acidulous radicals, in which the usual 
basylous character of the metals lias for the time disappeared. In hy- 
drides (p. 122) hydrogen itself is an acidulous radical. 

f Synonyms: sulphydric acid and sulphuretted hydrogen. 



262 SALTS OF ACIDULOUS RADICALS. 

Rarer Acids. — The above acids contain the only acidulous group- 
ings that commonly present themselves in analysis or in pharma- 
ceutical operations. There are, however, several other acids (such 
as hypochlorous, nitrous, hypophosphorous, valerianic, benzoic, 
gallic, tannic, uric, Iryposulphurous, hydroferrocyanic, hydroferrid- 
cyanic, lactic, etc.) with which it is desirable to be more or less fa- 
miliar ; reactions concerning these will therefore be described. Ar- 
senious, arsenic, stannic, manganic, and chromic acids have already 
been treated of in connection with the metals they contain ; in prac- 
tical analysis they always become sufficiently altered to come out 
among the metals. 

Quantivalence. — A glance at the foregoing Table is sufficient to 
show the quantivalence of the acidulous radicals. The first seven 
are clearly univalent, then follow six bivalent, leaving three triv- 
alent. 

These all combine with equivalent amounts of basylous radicals to 
form various salts ; hence they may be termed monobasylous. dibasy- 
lous, and tribasylous radicals. The acids themselves were formerly 
spoken of as monobasic, dibasic, and tribasic respectively, or mono- 
basic and polybasic, in reference to the amount of base (hydrates or 
oxides) they could decompose ; but the terms are no longer definite, 
and hence but little used in mineral chemistry. 

Antidotes. — The antidotes in cases of poisoning by the strong 
acids will naturally be non-corrosive alkaline substances, as soap 
and water, magnesia, common washing " soda, v or other carbonates. 
Vinegar, lemon-juice, and weak or non-corrosive acids would be the 
appropriate antidotes to caustic alkalies. 

Analysis. — The practical study of the acidulous side of salts will 
occupy far less time than the basylous. Salts will then be briefly 
examined as a whole. 

Caution. — Once more : it is only for convenience in the division of 
chemistiw for systematic study that salts may be considered to contain 
basylous and acidulous radicals, or separate sides, so to speak ; for Ave 
possess no absolute knowledge of the internal arrangement of the 
atoms (admitting that there are such things) in the molecule of a salt. 
We only know that certain groups of atoms may be transferred from 
compound to compound in mass (that is, without apparent decom- 
position) ; hence the assumption that these groups are radicals. A 
salt is probably a whole, having no such sides as those mentioned. 



QUESTIONS AND EXERCISES. 

410. Mention the basylous radical of acids. 

411. Give illustrations of univalent, bivalent, and trivalent acidu' 
lous radicals, or monobasylous, dibasylous, and tribasylous radicals. 

412. What is the difference between an elementary and a com- 1 
pound acidulous radical ? 

413. Name the grounds on which salts may be assumed to contain 
basylous and acidulous radicals. 



CHLORIDES. 2G3 

HYDROCHLORIC ACID AND OTHER CHLORIDES. 

Formula of Hydrochloric Acid HC1. Molecular weight* 3G.4. 

The acidulous radical of hydrochloric acid and of other chlorides 
is the element chlorine (CI). It occurs in nature chiefly as chloride 
of sodium (NaCl), either solid, under the name of rock-salt, mines 
of which are not unfrequently met with, or in solution in the water 
of all seas. Common table-salt is more or less pure chloride of sodium 
in minute crystals. Chlorine, like hydrogen, is univalent (CK) ; its 
atomic weight is 35.4. Its molecule is symbolized thus, Cl 2 , chloride 
of chlorine. 

Reactions. 
Hydrochloric Acid. 
First Synthetical Reaction. — To a few fragments of chloride 
of sodium in a test-tube or small flask add about an equal 
weight of sulphuric acid ; colorless and invisible gaseous hydro- 
chloric acid is evolved, a sulphate of sodium remaining. Adapt 
to the mouth of the vessel by a perforated cork a piece of glass 
tubing bent to a right angle, heat the mixture, and convey the 
gas into a small bottle containing a little water ; solution of 
hydrochloric acid results. 

NaCl + H 2 SO* = HC1 + NaHS0 4 

Chloride of Sulphuric Hydrochloric Acid sulphate 

sodium. acid. acid. of sodium. 

Hydrochloric Acid. — The product of this operation is the nearly 
colorless and very sour liquor commonly called hydrochloric acid. 
When of certain given strengths (estimated by volumetric analysis) 
it forms Acidum Hyclrochlcricum, U. S. P. (Acidum Muriaticum), 
and Acidum Hydrochloricum Dilutum, U. S. P. The former has a 
specific gravity of 1.16 and contains 31.9 per cent, of real acid. 
The latter, specific gravity 1.049, with 10 per cent, of the real acid, 
is made by diluting 6 fluid parts of the strong acid with 13 of water. 
The above process is that of the manufacturer, larger vessels being 
employed, and the gas being freed from any trace of sulphuric acid 
by washing. Other chlorides yield hydrochloric acid when heated 
with sulphuric acid ; but chloride of sodium is always used, because 
cheap and common. 

Common yellow hydrochloric acid is a by-product in the manu- 
facture of carbonate of sodium from common salt, a process in which 
the chloride of sodium is first converted into sulphate, hydrochloric 
acid being liberated. This impure acid is liable to contain iron, 
arsenic, fixed salts, sulphuric acid, sulphurous acid, nitrous com- 
pounds, and chlorine. 

The process for the preparation of hydrochloric arid is as follows: 
it may be carried out by the student with about one-twelfth ol' the 
quantities mentioned : — 

* The weight of a molecule is the sum of the weights of 'us atoms. 



264 



SALTS OF ACIDULOUS RADICALS. 



" Take of chloride of sodium, dried, 48 ounces, sulphuric acid 44 
fluidounces, water 36 fluidounces, distilled water 50 fluidounces ; 
pour the sulphuric acid slowly into 32 ounces of the water, and, 
when the mixture has cooled, add it to the chloride of sodium pre- 
viously introduced into a flask having the capacity of at least one 
gallon. Connect the flasks by corks and a bent glass tube with a 
three-necked wash-bottle, furnished with a safety-tube, and contain- 
ing the remaining 4 ounces of the water [or let the flask-tube pass 
loosely through a wider tube fixed in the cork of the wash-bottle, as 
shown in Fig. 37] ; then, applying heat to the flask, conduct the 

Fig. 37. 




Preparation of Hydrochloric Acid. 

disengaged gas through the wash-bottle into a second bottle contain- 
ing the distilled water, by means of a bent tube dipping about half 
an inch below the surface, and let the process be continued until the 
product measures 36 ounces, or the liquid has acquired a specific 
gravity of 1.16. The bottle containing the distilled water must be 
kept cool during the whole operation." 

The modification of wash-bottle shown in the figure allows of the 
easy insertion or removal of a delivery-tube. The wider tube there 
shown, or an ordinary tube-funnel, also acts as a safety-tube by ad- 
mitting air the moment there is any tendency in the water in the 
receiver to be forced back on account of a too rapid absorption of 
the gas. The time of the student will be saved if hydrochloric acid 
already in stock be placed in the wash-bottle instead of water. 

Invisible gaseous hydrochloric acid forms visible grayish-white 
fumes on coming into contact with air. This is due to combination 
with the moisture of the air. The intense greediness of hydro- 
chloric gas and water for each other is strikingly demonstrated on 
opening a test-tube full of the gas under water ; the latter rushes 
into and instantly fills the tube. If the water is tinged with blue 
litmus, the acid character of the gas is prettily shown at the same 
time. The test-tube, which should be perfectly dry, may be filled 
from the delivery-tube direct ; for the gas is somewhat heavier than, 
and therefore readily displaces, air. The mouth may be closed by 



CHLORIDES. 265 

the thumb of the operator. At low temperatures hydrochloric acid 
and water form a crystalline compound, HC1,2H 2 0. 

fibte. — The process includes the use of as much sulphuric acid as 
is theoretically necessary for the production of acid sulphate of 
sodium (NaHS0 4 ), which remains in the generating vessel. A hot 
solution of this residue, carefully neutralized by carbonate of sodium, 
filtered, and set aside, yields normal sulphate (Sodii Sulphas, U. S. 
P.), "Glauber's Salt," in the form of transparent oblique efflor- 
escent prisms (Na 2 SO 4 ,10H 2 O). 

2NaHS0 4 + Na 2 00, = 2Na 2 $0 4 + H 2 + C0 2 

Acid sulphate Carbonate of Sulphate of Water. Carbonic 

of sodium. sodium. sodium. acid gas. 

Chlorine. 

Second Synthetical Reaction. — To some drops of hydrochloric 
acid (that is, the common aqueous solution of the gas) add a 
few grains of black oxide of manganese, and warm the mixture; 
chlorine, the acidulous radical of all chlorides, is evolved, and 
may be recognized by its peculiar odor or irritating effect on 
the nose and air-passages. 

4HC1 + MnO, = Cl 2 + 2H 2 + MnCl 2 . 

Chlorine-water. — This is the process of the Pharmacopoeia for the 
production of chlorine-water (Aqua Chlori, U. S. P.), the gas being 
first washed and then passed into water. Chlorine slowly decom- 
poses water, with production of hydrochloric acid and oxygen gas ; 
hence, for medicinal purposes the solution should be freshly prepared ; 
it is best preserved in a green-glass well-stoppered bottle in a cool 
and dark place. At common temperatures (GO F.), if fresh and 
thoroughly saturated, chlorine-water contains more than twice (2.3) 
its bulk of chlorine, or less than 1 per cent, (about 0.75) by weight. 
Chlorine passed into cold water yields crystals of hydrous chlorine 
(CI 5H 2 0), and these when heated under pressure give an upper layer 
of chlorine-water and a lower layer of liquid chlorine. 

Note. — To obtain the chlorine from other chlorides, sulphuric acid 
as well as black oxide of manganese must be added. Hydrochloric 
acid is first formed. The action described in the foregoing equation 
then goes on, except that half instead of the whole of the oxygen 
of the black oxide is available for the removal of the hydrogen from 
the chlorine of the hydrochloric acid, the other half being taken up 
by the hydrogen of the sulphuric acid. Thus, supposing common 
salt to be the chloride used, the following equations may represent 
the supposed steps of the process : — 

2NaCl -|- H.,S0 4 = Na,S0 4 + 2HCI, 
Mn( ), -| H 2 S0 4 = MnS0 4 + 11,0 + ; 
then the 2HC1+0 = II 2 + Cf, 



266 SALTS OF ACIDULOUS KADICALS. 

or the whole may be included in one equation : — 

2NaCl + Mn0 2 + 2H 2 S0 4 = Na 2 S0 4 + MnS0 4 + 2H 2 + Cl 2 . 

This reaction may occasionally have analytical interest, a very 

small quantity of combined chlorine being recognized by its means. 

But the following test is nearly always applicable for the detection 

of this element, and leaves nothing to be desired in point of delicacy. 

Analytical Reactions (Test). 
To a drop of hydrochloric acid, or to a dilute solution of any 
other chloride, add solution of nitrate of silver ; a white curdy 
precipitate falls. Pour off most of the supernatant liquid, add 
nitric acid and boil ; the precipitate does not dissolve. Pour 
off the acid, and add dilute ammonia ; the precipitate quickly 
dissolves. Neutralize the solution by an acid ; chloride of silver 
is once more precipitated. 

The formation of this white precipitate, its appearance, insolu- 
bility in boiling nitric acid, solubility in ammonia and in solution 
of its carbonate and reprecipitation by an acid, form abundant evi- 
dence of the presence of chlorine. Its occurrence as a chloride of 
a metal is determined by testing for the metal with the appropriate 
reagent ; its occurrence as hydrochloric acid is considered to be 
indicated by the odor, if strong, and the sour taste, if weak, of the 
liquid, and the action of the liquid on blue litmus-paper, which, like 
other acids, it reddens. If hydrochloric acid be present in excessive 
quantity, it will, in addition to the above reactions, give rise to 
strong effervescence on the addition of a carbonate, a chloride being 
formed. The chlorine in insoluble chlorides, such as calomel, " white 
precipitate," etc., may be detected by boiling with caustic potash, 
filtering, acidulating the filtrate by nitric acid, and then adding the 
nitrate of silver. 

Antidotes. — In cases of poisoning by strong hydrochloric acid, 
solution of carbonate of sodium (common washing soda) or a mix- 
ture of magnesia and water may be administered as an antidote. 



QUESTIONS AND EXERCISES. 

414. A specimen of official Hydrochloric Acid contains 31.8 per 
cent, by weight of gas, and its specific gravity is 1.16; work out a 
sum showing what volume of it will be required, theoretically, to 
mix with black oxide of manganese for the production of one gallon 
of chlorine-water, one fluidounce of which contains 2.66 grains of 
chlorine. Ans. 5J nuidounces, nearly (5.4). 

415. Why does hydrochloric acid gas give visible fumes on com- 
ing into contact with air ? 

416. How much chloride of sodium will be required to furnish 
one pound of chlorine? 

417. Give the analytical reactions of chlorides. 



BROMIDES. 267 

418. What antidotes may be administered in cases of poisoning 
by hydrochloric acid? 



HYDROBROMIC ACID AND OTHER BROMIDES. 

Formula of Hydrobromic Acid HBr. Molecular weight 80.8. 

Bromine : Source, Preparation, and Properties. — The acidulous 
radical of hydrobromic acid and other bromides is the element bro- 
mine, Br (Bromum, U. S. P.). It occurs in nature chiefly as bro- 
mide of magnesium (MgBr 2 ) in sea-water and certain saline springs, 
and is commonly prepared from the bittern, or residual liquors of 
salt-works. It may be liberated from its compounds by the process 
for chlorine from chlorides — that is, by heating with black oxide of 
manganese and sulphuric acid (see page 265). It is a dark-red vola- 
tile liquid, emitting an odor more irritating, if possible, than chlo- 
rine—of specific gravity 2.990, boiling-point 135° to 145.4° F. 

Test of purity, U. S. P. — If 3 gm. of Bromine be mixed with 30 
c.c. of water and enough water of ammonia to render the solution 
colorless, the liquid then digested with carbonate of barium, filtered, 
evaporated to dryness, and the residue gently ignited, the latter 
[chiefly bromide of barium] should be soluble in absolute alcohol 
without leaving more than 0.26 gm. of residue [chloride of barium] 
(abs. of more than 3 per cent, of chlorine). If an aqueous solution 
of Bromine be poured upon reduced iron and shaken with the latter 
until it has become nearly colorless, then filtered, mixed with gelat- 
inized starch, and a few drops of Bromine solution be now carefully 
poured on top, not more than a very faint blue zone should appear 
at the line of contact of the two liquids (limit of iodine). 

Quantivalence. — The atom of bromine, like that of chlorine, is 
univalent (Br'). The atomic weight of bromine is 79.8. Free bro- 
mine has the molecular formula Br 2 , bromide of bromine. 

Fig. 38. 




Preparation of ITydrobronn'c Acid. 

Hydrobromic Acid. — The bromide of hydrogen, hydrobromic acid. 
may be made by decomposing bromide of phosphorus by water — ■ 
PBr 6 -f 4H 2 = 5HBr + JH 8 P0 4 . A small quantity may be pre- 
pared by placing seven or eight drops of bromine at the bottom ol' 



268 SALTS OF ACIDULOUS RADICALS. 

a test-tube, putting in fragments of glass to the height of about an 
inch or two, then ten or eleven grains of phosphorus, then another 
inch of glass, and finally a couple of inches of glass fragments 
slightly wetted with water, a delivery-tube being fitted on by a 
cork. The phosphorus combines readily, almost violently, with the 
bromine as soon as the vapor of the latter, aided by a little warmth 
from a flame, rises to the region of the phosphorus. The bromide 
of phosphorus thus formed then suffers decomposition by the water 
of the moist glass, phosphoric and phosphorous acids being pro- 
duced. The hydrobromic acid gas passes over (heat being applied 
in the after part of the operation), and may be condensed in water 
or in solution of ammonia. The latter solution on evaporation 
yields bromide of ammonium. 

Other Methods. — One hundred parts of sodium hyposulphite, fifty 
of bromine, and ten of water, are placed in a flask and the generated 
gas is conducted into the upper portion of 140 parts of water con- 
tained in another vessel. When the gas begins to come over slowly, 
gentle heat is applied. The product is nearly 190 parts of liquid 
containing 25 per cent, of real acid; specific gravity 1.204. It 
should be kept in a cool dark place {Hager). Squibb prefers to 
decompose solution of bromide of potassium by sulphuric acid, 
and, after removal of potassium sulphate by crystallization, to 
distil the residual fluid. Wade prescribes an almost pure clear 
solution of the acid made by shaking together 120 grains of bro- 
mide of potassium and 153 grains of crystallized tartaric acid in 1 
ounce of distilled water, and setting aside till precipitation of acid 
tartrate of potassium ceases. Goebel decomposes bromide of barium 
by an equivalent weight of sulphuric acid • preparing the bromide 
of barium by heating a wet mixture of bromide of ammonium and 
carbonate of barium until carbonate of ammonium fumes cease to 
be evolved. Fletcher prefers to pass sulphuretted hydrogen gas 
through water containing bromine, and, when all bromine has dis- 
appeared, distilling the mixture. The distillate, when diluted until 
it has a sp. gr. of 1.300, contains 34 per cent, of HBr. 

10Br 2 + 4H 2 S + 8H 2 = 20HBr + 2H 2 S0 4 + S 2 . 

Acidum Hydrobromicum Dilutum, U. S. P., has a sp. gr. of 1.077 
and contains 10 per cent, of HBr. 

Bromide of Potassium (KBr) is very largely employed in phar- 
macy, and is the salt, therefore, which may be used in studying the 
reactions of this acidulous radical. The official method of making 
the salt has been alluded to under the salts of potassium (page 76). 

Other Bromides are often used ; they may be prepared in the same 
way as, and closely resemble, the corresponding chlorides or iodides. 
Bromide of Sodium (Sodii Bromidum, U. S. P.) crystallizes in an- 
hydrous cubes (NaBr) from solutions at 110° or 120° F., and in 
hydrous prisms (NaBr,2II.,0) at ordinary temperatures. 

Bromide of Ammonium (XH^Br) (Ammonii Bromidum, U. S. P.) is 
prepared by agitating iron wire with a solution of bromine until the 
odor of bromine can be no longer perceived, adding solution of am- 
monia, filtering, and evaporating the filtrate to dryness. It forms a 



BROMIDES. 269 

white granular salt, which becomes slightly yellow on exposure to 
air, is readily soluble in water, less so in spirit, and, when heated, 
sublimes. Bromide or Iodide of Ammonium may also be made by 
mixing equivalent quantities of strong hot, aqueous solutions of the 
corresponding potassium salts and of sulphate of ammonium. To 
the cooled liquids rectified spirit is added, which precipitates the 
sulphate of potassium. The spirit recovered, by distillation of the 
clear liquid leaves the required salt as a residue in the retort. 

Bromide of Calcium, CaBr 2 (Calcii Bromidum, U. S. P.), may be 
prepared by neutralizing hydrochloric acid by hydrate or carbonate 
of calcium, filtering, and evaporating to dryness ; or by uniting bro- 
mine with iron, boiling the aqueous solution with lime until tho 
mixture is red, filtering and evaporating. It is a white deliques 
cent granular salt, soluble in water and in alcohol. 

Solution of Bromine, B. P., 10 minims in 5 ounces, is an aqueous 
solution, bromine being slightly soluble in water. 

Hypobromites, Bromates, Perbromates, analogous to hypochlorites, 
chlorates, and perchlorates, are producible. 

Bromates occurring as an impurity in bromides are detected by 
dropping diluted sulphuric acid on to the salt, when a yellow color; 
due to free bromine, is produced immediately if bromates are pres- 
ent. 

Analytical Reactions ( Tests). 

First Analytical Reaction, — To a few drops of solution of a 
bromide (KBr, or NB^Br) add solution of nitrate of silver ; a 
yellowish-white precipitate of bromide of silver (AgBr) falls. 
Treat the precipitate successively with nitric acid and dilute 
ammonia, as described for the chloride of silver ; it is only 
sparingly dissolved by the ammonia. 

Second Analytical Reaction. — To solution of a bromide add 
a drop or two of chlorine-water or a bubble or two of chlorine 
gas; then add a few drops of chloroform or ether, or disulphide 
of carbon, shake the mixture, and set the test-tube aside ; the 
chlorine, from the greater strength of its affinities, liberates the 
bromine, which is dissolved by the chloroform, etc., the solution 
falling to the bottom of the tube in the case of the heavy chlor- 
oform or bisulphide of carbon, or rising to the top in the case 
of the light ether. Either solution has a distinct yellow or 
reddish-yellow or red color, according to the amount of bromine 
present. 

Note. — This reaction serves for the isolation of bromine when 
mixed with many other substances. Excess of chlorine must be 
avoided, as colorless chloride of bromine is then formed. Iodides 
give a somewhat similar but more violet appearance ; the absence 
of iodine must therefore be insured by a process given in the next 
section.. Tho above solution in chloroform or ether may be re- 
moved from the tube by drawing up into a pipeth (small pipe — a 
narrow glass tube, usually having a bulb or expanded portion in 



270 SALTS OF ACIDULOUS RADICALS. 

the centre) the bromide fixed by the addition of a drop of solution 
of potash or soda, the chloroform or ether evaporated off, and the 
residue tested as described in the next reaction. 

The above operation is frequently employed for synthetical pur- 
poses. • 

Third Analytical Reaction. — Liberate bromine from a bro- 
mide by the cautious addition of chlorine or chlorine-water, 
then add a few drops of cold decoction of starch ; a yellow 
combination of bromine and starch, commonly termed " bro- 
mide of starch," is formed. 

Decoction of starch is made by rubbing down two or three 
grains of starch with some drops of cold water, then adding 
much more water and boiling the mixture. 

The above reaction may be varied by liberating the bromine 
by a little black oxide of manganese and a drop of sulphuric 
acid, the upper part of the inside of the test-tube being smeared 
over with some thick decoction of starch or thin starch-paste. 
Even sulphuric acid alone, if strong, liberates bromine from a 
bromide, the hydrogen of the hydrobromic acid first produced 
uniting with the oxygen of the sulphuric acid — the latter being 
reduced to sulphurous acid or even to hydrosulphuric acid. 

HYDKIODIC ACID AND OTHER IODIDES. 

Formula of Ilydriodic Acid HI. Molecular weight 127.6. 

Source. — The acidulous radical of hydriodic acid and other iodides is 
the element iodine (I). It occurs in nature as iodide of sodium and of 
magnesium in sea-water. Seaweeds, sponges, and other marine organ- 
isms, which derive much of their nourishment from sea-water, store up 
iodides in their tissues, and it is from the ashes of these that supplies 
of iodine {Iodum, U. S. P.) are obtained. Mineral iodides also are 
met with, and iodates occur in crude cubic nitre. 

Process. — The seaweed ash or kelp is treated with water, insoluble 
matter thrown away, and the decanted liquid evaporated and set 
aside to allow of the deposition of most of the sulphates, carbonates, 
and chlorides of sodium and potassium. The residual liquor is treated 
with excess of sulphuric acid, which causes evolution of carbonic and 
sulphurous or sulphuretted gases, deposition of sulphur and more 
sulphate of sodium, and formation of hydriodic acid. To the de- 
canted liquid is added black oxide of manganese, and the mixture is 
then slowly distilled ; the iodine sublimes, and is afterwards purified 
by re-sublimation. 

2HI + Mn0 2 + II 2 S0 4 = MnS0 4 + 2H 2 + I 2 - 
The analogy of chlorine, toomine, and iodine is well indicated by 
the fact that each is obtained from its compounds by the same reac- 



IODIDES. 271 

tion. Iodine is liberated from any iodide as bromine from bromides, 
or chlorine from chlorides — namely, by the action of black oxide of 
manganese and sulphuric acid. 

Properties. — Iodine is a crystalline purplish-black substance ; its 
vapor, readily seen on heating a fragment in a test-tube, is dark 
violet. Its vapors are irritating to the lungs, but a trace may be 
inhaled with safety ( Vapor Iodi, B. P.). It melts at 239°, boils at 
about 392° F., and is entirely volatilized, the first portions containing 
any cyanide of iodine that may, though very rarely, be present. The 
latter body occurs in slender colorless prisms, emitting a pungent 
odor. 

" A solution of Iodine in chloroform should be perfectly clear and 
limpid (abs. of moisture). When shaken with distilled water, it 
should not communicate to the latter more than a light brownish 
tinge, and no deep brown color (abs. of chloride of iodine). If the 
Iodine be removed from this dilute aqueous solution by agitation 
with disulphide of carbon, and, after the separation of the latter, 
some dilute solution of ferrous sulphate with a trace of ferric chloride 
be added, finally solution of soda, and the whole supersaturated with 
hydrochloric acid, no blue precipitate should make its appearance 
(abs. of cyanide of iodine). If Iodine be dissolved in sulphurous 
acid, the solution strongly supersaturated with ammonia, and com- 
pletely precipitated by nitrate of silver, the filtrate, on being super- 
saturated with nitric acid, should not at once become more than 
faintly cloudy (abs. of more than traces of chlorine or bromine).' ? 
U. S. P. 

This latter reaction is applied for the detection of chloride or 
bromide^ in Iodides, omitting the addition of sulphurous acid. 

Quantivalence. — The atom of iodine, like those of bromine and 
chlorine, is univalent* (F). The atomic weight of iodine is 12G.6, its 
molecular formula I 2 . 

The Iodide of Hydrogen, or Hydriodic Acid, is a heavy, colorless 
gas. Its solution in water may be made by passing sulphuretted 
hydrogen through water in which iodine is suspended. 

2II 2 S + 2I 2 = S 2 + 4III. 

Hydriodic acid may also be prepared by placing 20 parts of iodine 
and 2 of water in a retort, the neck of which points upward, and the 
end of the neck of which is connected by a glass tube with a bottle 

* There is a compound of iodine having the formula IC1 3 . Iodine 
would at first sight, therefore, seem to be a trivalent element (I'")* 
and bromine and fluorine, from their close chemical analogy with 
iodine, would necessarily be regarded as trivalent also. From this 
aspect the position of chlorine would be anomalous. Possibly, bow- 
ever, the compound is only a molecular combination o( chloride oi 
iodine, IC1, with chlorine, Cl 2 . Iodine also Conns with iodide of potas- 
sium a periodide, or tri-iodide, KI ; „ which may be obtained in lustrous 
prismatic crystals. This, too, may have the formula K 1,1 .. A mer- 
curic hexiodide (Hgl 6 , perhaps ligl.,,l..,l 2 ) is also known; and a per- 
iodide of ammonium, Nil,!.,,!.;. 



272 SALTS OF ACIDULOUS RADICALS. 

or other vessel containing a little water. Into the tubulure of the 
retort is passed, at first a drop at a time, a mixture of 1 part of red 
phosphorus with 2 of water. Abundance of hydriodic acid is 
evolved on the application of gentle heat, and falls into and dissolves 
in the water in the receiver. Phosphoric acid remains. 

P 2 + 51, + 811,0 = 10HI + 2H 3 P0 4 . 

Or iodine may be dissolved in bisulphide of carbon in a tall 
cylinder, water added, and sulphuretted hydrogen passed through 
the mixture. The water dissolves the hydriodic acid, the bisulphide 
retaining the separated sulphur. The aqueous solution only needs 
boiling for two or three minutes to remove excess of sulphuretted 
hydrogen. 

Syrupus Acidi Hydriodici, U. S. P., contains 1 per cent, of real 
acid. 

Iodide of potassium (KI) is largely used in medicine, and hence is 
the most convenient iodide on Avhich to experiment in studying the 
reactions of this acidulous radical. Solid iodine itself might be taken 
for the purpose ; but its use and action in that state have already 
been alluded to in describing the iodides of potassium, cadmium, 
and mercury ; its analytical reactions in the combined condition are 
those which may now occupy attention. 

Solution of Iodine.— Iodine is slightly soluble in water (iodine- 
water), and readily soluble in an aqueous solution of iodide of 
potassium. Five parts of iodine and 10 of iodide of potassium 
dissolved in 85 of distilled water, form Liquor Iodi Compositus, 
U. S. P. ("Lugol's Solution") ; 4 parts of iodine and 1 of iodide of 
potassium, rubbed with 2 parts of water and 93 of benzoated lard 
form Unguentum Iodi, U. S. P. It is more soluble in spirit {Tinc- 
tura Iodi, U. S. P.), or in a spiritous solution of iodide of potassium 
(77 net ura Iodi, B. P.). It combines with sulphur, forming an un- 
stable grayish-black solid iodide (S 2 I 2 ), having a radiated crystalline 
structure (Sulphuris Iodidum, U. S. P.). If 100 parts be thoroughly 
boiled with water, the iodine will pass off in vapor, and about 20 
parts of sulphur remain. — B. P. and U. S. P. 



Analytical Reactions ( Tests). 

First Analytical Reaction. — To a few drops of an aqueous 
solution of an iodide (c. g., KI) add solution of nitrate of sil- 
ver ; a light yellow precipitate of iodide of silver (Agl) falls. 
Pour away the supernatant liquid and treat the precipitate with 
nitric acid, it is not dissolved; pour away the acid and then add 
dilute ammonia, it is only sparingly dissolved. 

This reaction is useful in separating iodine from most other acid- 
ulous radicals, but does not distinguish iodine from bromine. 

The presence of chloride in iodide of silver may be detected by 
boiling with dilute solution of carbonate of ammonium, filtering off 



IODIDES. 273 

the insoluble iodide of silver and saturating the filtrate with nitric 
acid 5 any chloride of silver is then precipitated. 

Ammonia, it will be remembered, dissolves chloride of silver 
readily ; hence the presence of chloride of potassium in bromide or 
iodide may be detected by dissolving in water, adding excess of 
nitrate of silver, collecting the precipitate, washing, digesting in 
ammonia, filtering, and adding excess of nitric acid to the filtrate ; 
more than a trace of white curdy precipitate indicates a chloride (of 
potassium). Bromide and iodide of silver are, however, slightly sol- 
uble in ammonia. Better processes are given on page 275. 

Second Analytical Reaction. — Liberate iodine from an iodide 
by the cautious addition of chlorine, then add cold decoction 
of starch ; a deep-blue combination of iodine and starch, com- 
monly termed " iodide of starch," is formed. 

Starch is highly sensitive to the action of iodine : this reaction is 
consequently very delicate and characteristic. The reaction is not 
observed in hot liquids. Excess of chlorine must be avoided, or 
colorless chloride of iodine will be produced. Nitrous acid, or a 
nitrite acidulated with sulphuric acid, may be used instead of chlo- 
rine. Concentrated sulphuric acid also liberates iodine from iodides, 
the hydrogen of the hydriodic acid first produced uniting with the 
oxygen of the sulphuric acid — the latter (H 2 S0 4 ) being reduced to 
sulphurous acid (H 2 S0 3 ) or even to hydrosulphuric acid (H 2 S). 

In testing bromine for iodine the bromine must be nearly all re- 
moved by dilute solution of sulphurous acid, or be nearly all re- 
moved by solution of soda, before the decoction of starch is added. 

Ozone (0 3 ). — Papers soaked in mucilage of starch containing 
iodide of potassium form a test for free chlorine and nitrous acid, 
and are also employed by meteorologists to detect an allotropie or 
physically polymeric and energetic form of oxygen termed by 
Schonbein ozone (from 6<>, ozo, I smell). This substance liberates 
iodine from iodide of potassium (with formation of iodide of starch), 
and is supposed to occur normally in the atmosphere, the salubrity 
or insalubrity of which is said to be dependent to some extent on 
the presence or absence of ozone. The possible occurrence of 
nitrous or chlorinoid gases in the air, however, renders the test 
untrustworthy. Ilouzeau proposes to test for ozone by exposing 
litmus-paper of a neutral tint soaked in a dilute solution of iodide 
of potassium; the potash set free by action of the ozone turns the 
paper blue. The same paper without iodide would indicate the 
extent to which the effect might be due to ammonia vapor. ' Ozone, 
or rather ozonized air, is produced artificially in large quantities on 
passing air through a box (Beane's Ozone-generator) highly charged 
with electricity. In the latter operation condensation of the volume 
of air, or, rather, of the oxygen in the air, occurs. Small quantities 
are obtained by exposing in a, loosely closed bottle a stick of phos- 
phorus partially covered by water, but the product is mixed with 
peroxide of hydrogen. Ozone is a powerful bleaching, disinfecting, 
and general oxidizing agent; insoluble in water, soluble in oils of 



274 SALTS OF ACIDULOUS RADICALS. 

turpentine, cinnamon, and some other liquids. From experiments 
that have been made by Soret on the specific gravity of ozone, its 
molecular formula would seem to be 3 , that of ordinary oxygen 
being 2 . Its smell is peculiar. (See p. 236, also " Blood.*') 

Third Analytical Reaction. — To a neutral aqueous solution 
of an iodide, add a solution containing one part of sulphate of 
copper to two and a half parts of green sulphate of iron, and 
well shake ; a dirty-white precipitate of cuprous iodide (Cu 2 L) 
falls. 

2KI + 2CuSO, + 2FeSO, = Cu 2 I 2 + K 2 S0 4 + Fe 2 3S0 4 . 

Or to the liquid containing an iodide add the solution of cop- 
per sulphate and some solution of sulphurous acid, and warm 
the mixture, cuprous iodide falls. 

2KI + 2CuS0 4 + H 2 S0 3 + H 2 - Cu 2 I 9 + 2KHSO, 
+ H 2 S0 4 .' 

Separation of Chlorides, Bromides, and Iodides. — Chlorides and 
bromides are not affected in this way •, the reaction is useful, there- 
fore, in removing iodine from a solution in which chlorides and bro- 
mides have to be sought. The total removal of iodine by the former 
of the two modifications of the process is insured by supplementing 
the addition of the cupric and ferrous sulphates by a few drops of 
solution of potash or soda, any acid which might be keeping cuprous 
iodide in solution being thereby neutralized, ferric or ferrous hy- 
drate, precipitated at the same time, not affecting the reaction. 
Occasionally, too, it may be necessary to repeat the process with the 
filtrate before the last traces of iodine are removed. The second 
modification of the process is, on the whole, to be preferred. 

Chloride of the rare metal palladium performs a similar useful 
office in removing iodine, but not bromine or chlorine, from solu- 
tions. 

Chlorides may be separated from bromides by taking advantage 
of the ready solubility of chloride of silver, and slow and slight 
solubility of bromide of silver in ammonia, especially in (a fair, not 
a great, excess of) ammonia containing chloride of silver. 

The presence of much bromide of silver, however, considerably 
reduces the power of ammonia to dissolve chloride of silver. 

Hart's Test. — (If nitrates, chlorates, bromates, or iodates are pres- 
ent, it is necessary to fuse the substance with a little sodium car- 
bonate and charcoal to reduce them. If the haloids are united with 
silver, it is best to fuse with sodium carbonate and extract with 
water, although with iodine and bromine it is not absolutely neces- 
sary.) The substance is placed in the flask shown in the figure given 
in the section on quantitative analysis of oxide of manganese (aide 
Index), with some water and a few drops of solution of ferric sul- 
phate. In the bulbs are poured a few drops of dilute starch paste. 
The bulbs are kept cool by immersing in water in a beaker. The 



IODIDES. 275 

contents of the flask are then boiled, and if iodine is present the 
starch is colored blue. This test is extremely delicate. If iodine is 
found, the cork in the bulb-tube is removed and the solution boiled 
until on testing again' in the same way no more iodine is found. If 
much iodine is present, it is necessary to add more ferric sulphate 
solution. The bulb-tube is now cleaned, charged with a few drops 
of water and a drop or two of chloroform, and a very small crystal 
of potassium permanganate added to the solution in the flask. The 
contents of the flask are boiled again, and if bromine is present the 
chloroform becomes red. The tube is now moved and more potas- 
sium permangante and ferric sulphate added, little by little, boiling 
between each addition until the bromine has all been driven off. A 
few drops of alcohol are added to the contents of the flask to decol- 
orize any excess of permanganate, and after filtration chlorine is 
tested for in the filtrate Avith silver nitrate. 

Chlorides may also be detected in bromides and iodides by taking 
advantage of the formation of chlorochromic anhydride (page 237) 
and the non-occurrence of corresponding compounds of bromine or 
iodine, as follows : — 

To a solution of a chloride with a bromide and an iodide 
add a concentrated solution of sulphite of sodium, and then a 
reagent prepared by mixing equal volumes of sulphuric acid 
and saturated solution of sulphate of copper, until no further 
precipitation of cuprous iodide occurs. Next add solution of 
soda to remove excess of sulphate of copper ; filter and evap- 
orate to dryness. Place the dried residue, together with an 
equal bulk of red chromate of potassium, in a dry test-tube 
fitted with a delivery-tube, or into a small retort, and cover the 
mixture with sulphuric acid. Distil into water. Chromic an- 
hydride and hydrochloric and hydrobromic acids are liberated 
by the sulphuric acid, and reacting upon one another form 
chlorochromic anhydride, together with free bromine and 
shlorine. 

CrO, + 2HC1 = CrCIA + H 2 0. 

2CrO s + GHC1 + 3H 2 S0 4 = Cr 2 3S0 4 + 3C1 2 + 6H 2 0. 

2O0 3 + 6HBr + 3H 2 S0 4 == Cr 2 3S0 4 + 3Br 2 + 6H 2 0. 

The chlorochromic anhydride is decomposed by the excess 
of water into which it falls, giving rise to chromic acid, which 
imparts its color to the liquid, and hydrochloric acid. 

CrCLA + 2H 2 =■ H 2 Cr0 4 + 2HC1. 

The chlorine escapes and the bromine is dissolved by the 
water. The colored liquid is then shaken with chloroform, 
which removes the bromine — indicating bromine in the origi- 
nal - substance. A yellow color remaining is due to chromic 
acid, indicating chlorides in the original substance. Or add 



276 SALTS OF ACIDULOUS RADICALS. 

ammonia to the distillate — the color due to bromine is thereby 
entirely removed, while that of the chromic compound is only 
slightly modified. 

Instead of eliminating the iodine as cuprous iodide, it may be 
expelled in vapor, obvious enough by its color and odor, by fus- 
ing the dry mixture of the salts with excess of powdered red 
chromate. The residue, broken into small fragments, may then 
be distilled with the sulphuric acid for the detection of the 
bromine and chlorine. 

5KXr 2 T + 6KI = 8K 2 CrC\ -f Cr 2 3 + 3L. 

Fourth Analytical Reaction. — Iodides have been shown to 
be useful in testing for mercuric salts (see the Mercury reac- 
tions, p. 202) : a mercuric salt (corrosive sublimate, for ex- 
ample) may therefore be used in testing for iodides, a scarlet 
precipitate of mercuric iodide (HgL) being produced. 

This reaction may be employed where large quantities of an 
iodide are present : but its usefulness in analysis is much im- 
paired by the fact that the precipitate is soluble in excess of .the 
dissolved iodide or in excess of the mercuric reagent. Its color and 
insolubility in water distinguish it from mercuric chloride, bromide, 
and cyanide, which are white soluble salts. 

Fifth Analytical Reaction. — Iodides have also (see the Lead 
reactions, p. 212) been shown to be useful in testing for lead 
salts : similarly a lead salt (acetate, for example) may be used 
in testing for iodides, in solutions which are either neutral or 
faintly acid with acetic acid, a yellow precipitate of iodide of 
lead (PbL), soluble in hot water and crystallizing in yellow 
scales on cooling, being produced. 

Chloride, bromide, and cyanide of lead are white : hence the above 
reaction may occasionally be useful in distinguishing iodine from the 
allied radicals. But iodide of lead is slightly soluble in eoM water ; 
hence small quantities of iodide cannot be detected by this reaction. 
(For lodates see p. 294.) 

Analogies between Chlorine. Bromine. Iodine, and their Compounds. 
— These elements form a natural group or family, each distinct from 
the other, yet closely related. Moreover, their dissimilarities are so 
curiously gradational as to irresistibly suggest the idea that some 
day we may find the differences between these bodies to be in de- 
gree rather than in kind. Thus chlorine is a gas and iodine a 
solid, while bromine occupies the intermediate condition. The 
atomic weight of bromine is nearly midway between those of 
chlorine and iodine. The same may be said of the weight of 
equal volumes of each in the ga>eous state. The specific gravity 
of fluid chlorine is 1.33. of iodine 4.95. while bromine is nearly 3. 
Liquid chlorine is transparent, iodine opaque, bromine intermediate. 



CYANIDES. 277 

The crystalline forms of the chloride, bromide, and iodide of a metal 
are commonly identical. One volume of either element in the gas- 
eous state combines with an equal volume of hydrogen (at the same 
temperature) to form two volumes of a gaseous acid, very soluble in 
water (hydrochloric acid, hydrobromic acid, hydriodic acid). Many 
other analogies are traceable. ( Vide Index, " Periodic Law.") 



QUESTIONS AND EXERCISES. 

419. State the method by which Bromine is obtained from its nat- 
ural compounds. 

420. Mention the properties of bromine. 

421. How may the Bromides of Potassium and Ammonium be 
made ? 

422. By what reagents may bromides be distinguished from chlo- 
rides ? 

423. Whence is iodine obtained? 

424. By what process is iodine isolated ? 

425. State the properties of iodine. 

426. What is the nature of Iodide of Sulphur? 

427. Give the analytical reaction of iodides. 

428. Which three substances may indirectly be detected by a mix- 
ture of iodide of potassium and mucilage of starch ? 

429. Describe a method by which iodides may be removed from a 
solution containing chlorides and bromides. 



HYDROCYANIC ACID AND OTHER CYANIDES. 

Formula of Hydrocyanic Acid HON or HCy. 
Molecular weight 27. 

History of Cyanogen. — The acidulous radical of hydrocyanic acid 
and other cyanides is a compound body, cyanogen (Cy). It is so 
named from nvavoq, Jcuanos, blue, and yevvdu, gennao, I generate, in 
allusion to its prominent chemical character of forming, with iron, 
the different varieties of Prussian blue. It was from Prussian blue 
that Scheele, in 1782, first obtained what we now, from our know- 
ledge of its composition, term hydrocyanic acid, but which he called 
Prussic acid. Cyanogen was isolated by Gay-Lussac in 1814. and 
was the first compound radical distinctly proved to exist. 

Sources. — Cyanogen does not occur in nature, and is only formed 
from its elements under certain circumstances. It is found in small 
quantities among the gases of iron-furnaces, and is produced to a 
slight extent in distilling coals for gas. In the form oi' ferrocyanide 
of potassium it is obtained abundantly by heating animal refuse 
containing nitrogen, such as the scrapings of horns, hoots, and 
hides (5 parts), With carbonate of potassium (2 parts) and waste iron 
(filings, etc.) in a covered iron pot. The residual mass is boiled with 



278 SALTS OF ACIDULOUS RADICALS. 

water, the mixture filtered, and the filtrate evaporated and set aside 
for crystals to form. The cyanogen, produced from the carbon 
and nitrogen of the animal matter, unites with the potassium, and 
afterwards, on boiling with water, with iron, to form what is often 
termed the yellow prussiate of potash or ferrocyanide of potassium 
(K / 4 Fe // Cy / 6 ,3H 2 0) (Potassii Ferrocyanidum, U. S. P.), a compound 
occurring in four-sided tabular yellow crystals. It contains the 
elements of cyanogen, yet it is not a cyanide, for it is not poisonous, 
and is otherwise different from cyanides ; it will be further noticed 
subsequently. From this salt all cyanides are directly or indirectly 
prepared. 

Cyanide of Potassium (KCy) (Potassii Cyanidum, XL S. P.), which 
is the most common, may be obtained by heating the ferrocyanide 
to redness until gas (chiefly nitrogen) ceases to be evolved ; a carbide 
of iron settles to the bottom of the molten mass of almost pure cy- 
anide. The product, carefully poured off and cooled, is an opaque 
crystalline mass containing about 95 per cent, of the salt. It also 
may be procured by fusing 8 parts of ferrocyanide with 3 of car- 
bonate of potassium in a crucible ; carbonic acid gas (C0 2 ) is evolved, 
iron (Fe) is set free, and cyanate of potassium (KCyO), a body that 
will be subsequently noticed, is formed at the same time : — 

2K 4 FeCy 6 -f 2K 2 C0 3 = lOKCy + 2KCyO -f Fe 2 + 2C0 2 . 

Double cyanides exist, such as the cyanide of sodium and silver 
(NaCy,AgCy), formed in the process (subsequently described) of 
quantitatively determining the amount of hydrocyanic acid in a 
liquid by a standard solution of nitrate of silver ; these compounds 
have, more or less, the properties of their constituents. But other 
cyanogen compounds, not double cyanides, occur in which the cyano- 
gen is so intiniatety united with a metal as to form a distinct radical ; 
such are ferrocyanides and ferricyanides — salts which will be noticed 
in due course. 

Cyanogen, like chlorine, bromine, and iodine, is univalent (Cy'). 
It may be isolated by simply heating mercuric cyanide (HgC}' 2 ) or 
cyanide of silver (AgCy). It is a colorless gas, burning, when 
ignited, with a beautiful peach-blossom-colored flame. 

Mercuric cyanide is produced in crystals on dissolving 1 part of 
ferrocyanide of potassium in 15 parts of boiling water, adding 2 parts 
of mercuric sulphate, keeping the whole hot for ten or fifteen minutes, 
and then filtering and setting aside to cool. In addition to mercuric 
cyanide (HgCy 2 ), mercury (Hg), ferric sulphate (Fe 2 3S0 4 ), and sul- 
phate of potassium (K 2 S0 4 ), are formed. Any excess of ferrocyanide 
also gives Prussian blue by reaction with the ferric sulphate. It 
(Hydrargyri Cyanidum, U. S. P.) may also be made by dissolving 
reel oxide of mercury in diluted hydrocyanic acid. A small flame 
of cyanogen may be obtained on heating a few crystals of mercuric 
cyanide in a short piece of glass tubing closed at one end, and apply- 
ing a light to the other end as soon as evolution of gas commences ; 
brown paracyanogen (C 3 X 3 ) and mercury remain. 



CYANIDES. 279 

Reactions. 

Diluted Hydrocyanic Acid. 

Synthetical Reaction. — Dissolve 2 or 3 grains of ferrocyanide 
of potassium in 5 or 6 times its weight of water in a test-tube, 
add a few drops of sulphuric acid and boil the mixture, con- 
veying the evolved gas by a bent glass tube (adapted to the 
test-tube by a cork) into another test-tube containing a little 
water ; the product is a dilute solution of hydrocyanic acid. 
Made by this process in large quantities of a certain definite 
strength (2 per cent.), this solution is the Acidum' Hydrocy- 
anicuni JDilutum, U. S. P. " A colorless liquid of a peculiar 
odor. Specific gravity 0.997." 

2K,FeCy 6 -f 6H 2 S0 4 = FeK 2 Fe"Cy 6 + 6KHS0 4 + GHCy. 

The following are the details of the official (U. S. P.) process : — 
Place 20 parts of Ferrocyanide of Potassium in coarse powder in 
a tubulated retort, and add to it forty (40) parts of Water. Con- 
nect the neck of the retort (which is to be directed upward), by 
means of a bent tube, with a well-cooled condenser, the delivery- 
tube of which terminates in a receiver surrounded with ice-cold 
water, and containing sixty (60) parts of Diluted Alcohol. All the 
joints of the apparatus, except the neck of the receiver, having 
been made air-tight, pour into the retort, through the tubulure, the 
Sulphuric Acid previously diluted with an equal weight of Water. 
Agitate the retort gently, and then heat it, in a sand-bath, until the 
contents are in brisk ebullition, and continue the heat regularly 
until there is but little liquid mixed with the saline mass remaining 
in the retort.* Detach the receiver, and add to its contents so much 
Distilled Water as may be required to bring the product to the 
strength of two (2) per cent, of absolute Hydrocyanic Acid. ( Vide 
paragraphs on quantitative analysis.) 

* This operation is peculiarly liable to those sudden and tumult nous 
evolutions of vapor, or " Dumpings," or " soubresauts" which often in- 
terfere with successful distillation. Such phenomena occur, according 
to Tomlinson, whenever unaided heat has to overcome the great amount 
of adhes'on naturally existing between certain liquids and vapors, or, 
rather, between the normal liquid and those particles of it which, be- 
coming strongly heated at the heated part of the vessel, have assumed 
the condition of particles of dissolved vapor, and which would at once 
pass from this condition into that of permanent vapor but for adhesion. 
Ordinarily a glass or other surface is not absolutely clean, but is more 
or less covered with specks, traces of materials deposited from the air, 
the fingers, cloths, etc. Some liquids seem to have little or no adhesion 
for these materials, while certain vapors have greater adhesion for the 
films than for the liquids. Hence, ill ordinary regular ebullitions the 
vapors accumulate on the films, and then at once become subject to the 
pressure of the mass of fluid, and so pass off in bubbles. But when 
the films are absent, or have become removed during distillation, the 



280 SALTS OF ACIDULOUS RADICALS. 

The residue of this reaction is acid sulphate of potassium (KHSO^).. 
which remains in solution, and ferrocyanide of potassium and iron 
(Fe // K 2 FeCy 6 ), an insoluble powder sometimes termed Everitt's 
yellow salt, from the name of the chemist who first made out the 
nature of the reaction. The latter compound becomes bluish-green 
during the reaction, owing to absorption of oxygen. 

Diluted hydrocyanic acid may also be prepared by reaction of 
cyanide of silver (6 parts), hydrochloric acid (5 parts), and distilled 

water (55 parts). Mix the hydrochloric acid with the distilled 

water, add the cyanide of silver, and shake the whole together in a 
glass-stoppered bottle. When the precipitate has subsided, pour off 
the clear liquid. 

Pure anhydrous hydrocyanic acid is a colorless, highly volatile, 
intensely poisonous liquid, solidifying when cooled to a low tempera- 
ture.* It may be made by passing sulphuretted hydrogen over mer- 
curic cyanide. The official solution of the acid is fairly stable, but 
is said to be rendered more so by the presence of a minute trace of 
sulphuric or hydrochloric acid. A stronger acid is liable to assimilate 
the elements of water, and yield formate of ammonium (NH 4 CH0 2 ). 
Solutions of hydrocyanic acid often become brown by formation of 
what is, apparently, paracyanogen (C 3 N 3 ). According to Williams, 
aqueous hydrocyanic acid containing 20 per cent, of glycerin can 
be kept for an apparently indefinite length of time. The official 
acid should be preserved in small stoppered bottles in a cool dark 
place. 

Note. — A few drops of diluted hydrocyanic acid so placed that its 
vapor may be inhaled, forms the Vapor Acid Hydrocyanici, B. P., 
or Inhalation of Hydrocyanic Acid. 

Hydrocyanic acid also occurs in cherry-laurel water and bitter- 
almond water (vide Index). Aqua Luuro-Cerasi, B. P., is made 
to contain 0.1 per cent, of real hydrocyanic acid (KCy.). 

The hydrocyanic acid used in pharmacy is extremely liable to vari- 
ation in strength. It should frequently be tested volumetrically. 

heat accumulates until it is sufficient to overcome the adhesion of the 
superheated particles, and these are then, all of them at once, con- 
verted into vapor, the liquid commonly boiling over, sometimes even 
bursting the vessel. "Bumping" would be prevented by the intro- 
duction of fragments of substances for which vapor-particles have ad- 
hesion, but no known substance has this property in an absolute degree. 
Fragments of tobacco-pipe or pumice-stone, pieces of cork, thick paper, 
resin, sulphur, platinum wire, etc., are all useful when there is no 
chemical action between them and the liquid. Mr. Tomlinson very 
strongly recommends cocoanut-shell charcoal to be used whenever 
practicable. A slow current of gas, such as hydrogen, air, or carbonic 
acid gas. also usefully promotes escape of vapor from a liquid. A jet 
of steam prevents bumping, but is not always applicable. When the 
bumping cannot well be prevented, as in the distillation of sulphuric 
acid, it is somewhat reduced in violence if the retort be heated by an 
annular gas-burner rather than by a single central jet. 

* Traces are formed when electricity passes between carbon poles in 
slightly moist air (Dewar). 



CYANIDES. 281 

Analytical Reactions ( Tests). 
First Analytical Reaction. — To a few drops of the hydro- 
cyanic acid solution produced in the above reaction, or to any 
solution of a cyanide, add excess of solution of nitrate of sil- 
ver ; a white precipitate of cyanide of silver (AgCy) falls. 
When the precipitate has subsided, pour away the supernatant 
liquid, and place half of the residue in another test-tube : to 
one portion add nitric acid, and notice that the precipitate does 
not dissolve ; to the other add ammonia, and observe that the 
precipitate, though soluble, dissolves somewhat slowly. (Chlo- 
ride of silver, which is also white, is readily soluble in am- 
monia.) Cyanide of silver dissolves in solutions of cyanides 
of alkali-metals, soluble double cyanides being formed (e. </., 
KCy,AgCy). 

Solubility of precipitates in strong solutions of salts. — Cyanide 
of silver and many other precipitates insoluble in acids (similar re- 
marks apply to precipitates insoluble in alkalies) are often soluble 
in the strong saline liquids formed by the addition of acids and 
alkalies to one another. Hence the precaution of adding the latter 
reagents to separate portions of a precipitate, or of not adding the 
one until the other has been poured away. 

Cyanogen in an insoluble cyanide, such as cyanide of silver itself, 
is readily recognized on heating the substance in a short piece of 
glass tubing closed at one end like a test-tube and drawn out at the 
other end, so as to have but a small opening ; on applying a flame, 
the escaping cyanogen ignites and burns with a characteristic peach- 
blossom tint. Metallic silver remains. 

Antidote. 

Second Analytical Reaction. — To a dilute solution of hydro- 
cyanic acid, or a soluble cyanide, add a few drops of solution 
of a ferrous salt and a drop or two of solution of a ferric salt 
(ferrous sulphate and ferric chloride are usually at hand) ; to 
the mixture add potash or soda (magnesia or carbonate of so- 
dium), and then hydrochloric acid; a precipitate of Prussian 
blue remains. The decompositions may be traced in the fol- 
lowing equations : — 

HCy + KHO - KCy + H.O 

2KCy + FeSG 4 = FeCy + K 2 S0 4 

4KCy + FeCy, = K 4 FeCy 6 or K 4 Fcy 

3K 4 Fcy + 2Fe 2 Cl 6 = 12KC1 + FeJFcy a . 

The test depends on the conversion of the cyanogen into ferro- 
cyanogen by aid of the iron of a ferrous salt, ami the combination 
of the ferrocyanogen, so produced, with the iron of a ferric salt. 
24* ' 



282 SALTS OF ACIDULOUS RADICALS. 

Hence a mixture of green sulphate of iron, solution of perchlo- 
ride of iron, and either magnesia or carbonate of sodium, is the 
recognized antidote in cases of poisoning by hydrocyanic acid or 
cyanide of potassium. 

In such an alkaline mixture the poisonous cyanide, by reaction with 
ferrous hydrate, is at once converted into innocuous ferrocyanide of 
potassium or sodium, etc. : should the mixture become acid, the fer- 
ric salt present reacts with the soluble ferrocyanide. forming insol- 
uble Prussian blue, which is also inert. From the rapidity of the 
action of these poisons, however, there is seldom time to prepare an 
antidote. Emetics, the stomach-pump, the application of a stream 
of cold water to the spine, and the above antidote, form the usual 
treatment. 

Third Analytical Reaction. — To solution of hydrocyanic 
acid add ammonia and common yellow sulphydrate of ammo- 
nium, and evaporate the liquid nearly or quite to dryness in a 
small dish, occasionally adding ammonia till the excess of 
sulphy Irate of ammonium is decomposed; add water and 
acidify the liquid with hydrochloric acid, and then add a drop 
of solution of a ferric salt ; a blood-red solution of sulpho- 
cyanide of iron will be formed. 

This is a very delicate reaction. Some free sulphur in the yellow 
sulphydrate of ammonium unites with the alkaline cyanide and forms 
sulphocyanate (2NH 4 Cy — S 2 =2NH 4 CyS) : the ammonia combines 
with excess of free sulphur, and forms, among other salts, sulphydrate 
of ammonium, the whole of which is removed by the ebullition. If 
the liquid has not been evaporated far enough, sulphydrate of am- 
monium may still be present, and give black sulphide of iron on the 
addition of ferric salt. 

Hydrorijanir- Acid in the Blood. — According to Buchner the blood 
of animals poisoned by hydrocyanic acid, instead of coagulating as 
usual, remains liquid and of a clear cherry-red color several da vs. 
In one case he obtained the reactions of the acid on diluting and dis- 
tilling the blood fifteen days after death, and applying the usual 
reagents to the distillate. Aqueous solution of peroxide of hydrogen 
(p. 102) changes such blood to a deep-brown color. 

Schonbein's test for hydrocyanic acid is said to be extremely deli- 
cate. _ Filtering-paper is soaked in a solution of 3 parts of guaiacum 
Tesin-in 100 of alcohol. A strip of this paper is dipped in a solution 
of 1 part of sulphate of copper in 50 of water ; a little of the sus- 
pected solution is placed on this paper and exposed to the air. when 
it immediately turns blue. Or the paper may be placed over the 
neck of an open bottle of medicine supposed to contain hydrocyanic 
acid, or otherwise exposed to the vapor of the acid. 



NITRATES. 283 



QUESTIONS AND EXERCISES. 

430. Write a paragraph on the history of cyanogen. 

431. Mention the source of the cyanogen of cyanides. 

432. How is Ferrocyanide of Potassium prepared ? 

433. What is the formula of ferrocyanide of potassium ? 

434. Is ferrocyanide of potassium poisonous ? 

435. Write an equation expressive of the reaction which ensues 
when ferrocyanide and carbonate of potassium are brought together 
at a high temperature. 

436. What are the properties of cyanogen ? How may it be ob- 
tained in a pure condition ? 

437. How is mercuric cyanide prepared ? 

438. How much real hydrocyanic acid is contained in the official 
liquid ? 

439. Give details of the preparation of hydrocyanic acid, and an 
equation of the reaction. 

440. State the proportion of water that must be added to an aque 
ous solution containing 15 per cent, of hydrocyanic acid to reduce 
the strength to 2 per cent. — Ans. 6J to 1. 

441. What are the characters of pure undiluted hydrocyanic acid ? 
How may it be obtained? 

442. Enumerate the tests for cyanogen, giving equations. 

443. Explain the action of the best antidote in cases of poisoning 
by hydrocyanic acid or cyanide of potassium. 



NITRIC ACID AND OTHER NITRATES. 

Formula of Nitric Acid HN0 3 . Molecular weight 63. 

Introduction. — The group of elements represented by the formula 
N0 3 is that characteristic of nitric acid and all other nitrates ; heme 
it is expedient to regard these elements as forming an acidulous 
radical, which may be termed the nitric radical. Like the hypo- 
thetical basylous radical ammonium (NH 4 ), this supposed acidulous 
radical (NO ;i ) has not been isolated. Possibly it is liberated when 
chlorine is brought into contact with nitrate of silver ; but, if so. its 
decomposition into white crystalline nitric anhydride (N 2 6 ) and 
oxygen (0) is too rapid to admit of its identification. 

Sources. — The nitrogen and oxygen of the air combine and ulti- 
mately form nitric acid whenever a current of electricity (as in the 
occurrence of lightning) passes. The nitrates found in rain may 
partly or wholly thus originate. The oxidation of ammoniacal mat- 
ter and of the nitrogenous constituents of animal and vegetable 
matter in the soil, favored by the darkness and by the presence 
of some low form of vegetable life acting as a ferment, result in 
the production of nitrates. Hence nitrates are commonly met 
with in waters, soils, and the juices of plants. In the concen- 
trated plant-juices, termed medicinal "Extracts," small prismatic 
crystals of nitrate of potassium may occasionally be observed. (The 



284 SALTS OF ACIDULOUS RADICALS. 

cubical crystals often met with on extracts are chloride of potas- 
sium.) Nitric acid and other nitrates are obtained from nitrates of 
potassium and sodium, and these form the surface layers of the soil 
of tropical countries. Nitrate of potassium or prismatic nitre (from 
the form of its crystals) is chiefly produced in and about the villages 
of India. The natives simply scrape the surface of waste grounds, 
mud-heaps, banks, and other spots where a slight incrustation indi- 
cates the presence of appreciable quantities of nitre, mix the scrap- 
ings with wood ashes (carbonate of potassium, to decompose the 
nitrate of calcium always present), digest the mixture in water, and 
evaporate the liquor. The impure product is purified by careful 
recrystallizations, and is sent into commerce in the form of white 
crystalline masses or fragments of striated six-sided prisms. Besides 
its use in medicine (Potassii Nitras, U. S. P.), it is employed in 
very large quantities in the manufacture of gunpowder. Charta 
Potassii Nitratis, U. S. P., Nitrate-of-Potassium Paper, is made by 
immersing strips of white unsized paper in a solution of 1 part of 
the salt in 4 parts of water and drying them. Nitrate of Sodium 
(Sodii Nitras, U. S. P.) occurs in deposits from 3 inches to 3 yards 
in thickness on and near the surface, and at any depth down to 
about 30 feet, in many parts of Peru, Bolivia, and Chili, but more 
especially in the district of Atacama. The mineral is termed 
caliche, and commonly contains 50 per cent, of nitrate of sodium. 
The latter is distinguished as Chili saltpetre or Chili nitre or (from 
the form of its crystals — obtuse rhomboids) cubic nitre, and is chiefly 
used as a manure and as a source of nitric acid, its tendency to 
absorb moisture unfitting it for use in gunpowder. In many parts 
of Europe nitrate of potassium is made artificially by exposing heaps 
of animal manure, refuse, ashes, and soil to the action of the air and 
the heat of the sun : in the course of a year or two the nitrogen of 
the animal matter becomes oxidized to nitrates ; the latter are re- 
moved by washing. According to Warington, the nitrifying fer- 
ment appears capable of existing in three conditions : — 1, the nitric 
ferment of soil, which converts both ammonium salts and nitrites 
into nitrates-, 2, the altered ferment, which converts ammonium salts 
into nitrites, but fails to change nitrites into nitrates ; and, 3, the sur- 
face organism (a bacterium), which changes nitrites into nitrates. 
Similar nitrification goes on in impure well and river waters, which 
thereby tend to become pure. 

Note. — The word nitric is from nitre, the English equivalent of 
the Greek virpov (nitron), a name applied to certain natural deposits 
of natron (carbonate of sodium), for which nitrate of potassium 
seems at first to have been mistaken. Saltpetre is simply sal petrce, 
salt of the rock, in allusion to the natural origin of nitrate of potas- 
sium. Sal prunella (from sal, a salt, and prima, a live coal) is 
nitrate of potassium melted over a fire and cast into cakes or bullets. 

The nitric radical is univalent (XCX/). 

Constitution of Salts. 
It is here necessary again to caution the reader against regarding 
salts as invariably possessing a known constitution, or supposing 



NITRATES. 285 

that they always possess two or more sides or contain definite rad- 
icals. The erroneous conception which, of all others, is most likely 
to be imperceptibly formed is that of considering salts to be binary 
bodies. For, first, the names of salts are necessarily binary. A 
student hears the names " sulphate of iron," " sulphate of copper," 
and simultaneously receives the impression that each salt has two 
sides, copper or iron occupying one, and something indicated by the 
words " sulphate of" the other. Such words as " vitriol," green or 
blue, or " nitre," would perhaps implant unitary ideas in the mind ; 
but it is simply impossible to give such names to all salts as will 
convey the impression that each salt is a whole, and therefore uni- 
tary. The name " sulphate of potash " produces binary impres- 
sions ; and the less incorrect name, " sulphate of potassium," is in 
this respect no better. Secondly, it is impracticable to study salts 
as a whole. Teachers are almost unanimous in the opinion that 
students should first master the reactions characteristic of the metals 
in salts, and then the residues which, with those metals, make up 
the salts, or vice versa. It is not only impracticable, but impossible, 
to study salts as a whole; binary ideas concerning them are there- 
fore almost inevitably imbibed. We come to regard a salt as a body 
which splits up in one direction only, look upon nitre, for instance, 
and all other nitrates, as containing N0 3 and a metal K ; whereas 
KN0 3 may be split up into KN0 2 and ; or into K 2 0, N 2 , and 5 ; 
or may contain K 2 and N 2 5 . These are the chief disadvantages 
attending the employment of the binary hypothesis in studying 
chemical compounds ; if they be borne in mind, the hypothesis may 
be freely used without much danger of permanent mental bias. 
Thus in nitre let the group of elements (N0 3 ) which, with potas- 
sium, makes up the whole salt be called the nitric radical, the name 
of the latter being directly derived from its hydrogen salt. Sim- 
ilarly allow the acidulous residues of other salts of metals to be 
termed respectively the chloric, acetic, sulphurous, sulphuric, car- 
bonic, oxalic, tartaric, phosphoric, citric, boracic radicals. In short, 
these compound radicals should be regarded as groupings common 
to many salts, and which may usually be transferred without any 
apparent breaking or splitting; at the same time we must be pre- 
pared to find that occasionally a salt divides in other directions. In 
this way perhaps erroneous impressions will gain least hold on the 
mind, and a way be left open for the easy entrance of new truths 
should the real constitution of salts be discovered. 

Formerly salts (such as sulphate of magnesium) were regarded as 
containing (a) an oxide of a metal (MgO) and an anhydride (SO ;i ), 
the latter being incorrectly called an acid (sulphuric acid) ; or (/>) as 
containing two simple radicals (e. //., KI, NaCl, KCy, HgS) — the 
former being called oxyacid sails, or oxy salts, and the latter haloid 
sails (from aXc, als, sea-salt, and kMog, eidos, likeness). Such dis- 
tinction is no longer maintained, the two classes being merged. 
This is an important educational gain on the side of simplicity ; for, 
whereas under the old system much time was necessarily expended 
before salts of a metal and salts o\' the oxide of that metal could be 
distinguished (e. g., Ivl and K a O,S0 8 ), now all salts being regarded 



286 SALTS OF ACIDULOUS RADICALS. 

as salts of the metals themselves {e.~ g., KI and K 2 S0 4 ), no such 
distinction is necessary. 

Reactions. 
Nitric Acid. 

Synthetical Reaction. — To a fragment of nitrate of potassium 
or nitrate of sodium in a test-tube add a drop or two of sul- 
phuric acid, and warm ; nitric acid (HN0 3 ) is evolved in vapor. 
The fumes may be condensed by a bent tube fitted to the test- 
tube, not by a cork as for hydrochloric acid — because the nitric 
vapors would strongly act on it — but by plaster of Paris, a 
paste of which sets hard on being set aside for a short time, 
and is unaffected by the acid. 

On a somewhat larger scale nitric acid may be prepared by 
heating, in a stoppered or plain retort, a mixture of equal 
weights of nitrate of potassium and sulphuric acid ; the acid 
distils over, and acid sulphate of potassium remains behind : — 

KN0 3 + H 2 SO, = HNO s + KHS0 4 

Nitrate of Sulphuric Nitric Acid sulphate 

potassium. acid. acid. of potassium. 

Half the quantity of sulphuric acid may be taken ; but in that 
case neutral sulphate of potassium (K 2 S0 4 ) is produced, which, from 
its hard, slightly soluble character, is removed with difficulty from 
the retort. On the manufacturing scale the less proportion is used 5 
but instead of retorts iron cylinders are emploj^ed, from which the 
residual salt is removed by chisels. Moreover, the cheaper sodium 
salt is the nitrate, from which manufacturers usually prepare nitric 
acid, seven parts of nitrate of sodium and four of sulphuric acid 
being employed. 

Note. — The acid sulphate of potassium is readily converted into 
neutral sulphate (Potassii Sulphas, U. S. P.) by dissolving in water, 
adding carbonate of potassium until effervescence ceases to occur, 
filtering, and setting aside to crystallize. 

Pure nitric acid (HNOY) is a colorless liquid, somewhat difficult 
of preparation ; its specific gravity is 1.52. The strongest acid met 
with in commerce has a sp. gr. of 1.5, and contains 93 per cent, of 
real nitric acid (HN0 3 ) ; it fumes disagreeably, is unstable, and, 
except as an escharotic, is seldom used. The United States Phar- 
macopoeia contains two acids: Acidum Nitricum, of sp. gr. 1.42, 
and containing 69.4 per cent, of real acid (HN0 3 ) ; and another, 
Acidum Nitricum Dilutum, sp. gr. 1.059, containing 10 per cent. 
The stronger liquid, although containing water, is usually simply 
termed "nitric acid/' The official nitric acid, of sp. gr. 1.42, is a 
definite hydrous acid (2HN0 3 ,3H 2 0) ; it distils at 250 6 F. without 
change. If a weaker acid be heated it loses water ; if a stronger 
acid be heated it loses nitric acid, until the density of 1.42 is reached. 
Aqua fortis is an old name for nitric acid {Aqua fortis simplex, 
sp. gr. 1.22 to 1.25; Aqua fortis duplex, 1.36). The strength of a 



NITRATES. 287 

specimen of nitric acid is determined by volumetric analysis. Nitric 
anhydride (N 2 5 ), sometimes but erroneously called anhydrous nitric 
acid, is a solid crystalline substance formed on passing dry chlorine 
over dry nitrate of silver. Metals reduce nitric acid to nitrous acid 
and to the various oxides of nitrogen, or even to nitrogen itself, ac- 
cording to the strength of acid, temperature, and amount of nitrate 
present. Not unfrequently nitrate of ammonium is simultaneously 
formed. Thus, with zinc : — 

IOHNO3 + 2Zn 2 = 4(Zn2N0 3 ) -f NH 4 N0 3 + 3H 2 0. 

Aqua Regia. — Four parts of nitric acid and fifteen of hydrochloric 
acid by weight form the Acidum Nitrohydrochloricum, U. S. P., and 
the same weights with 76 of water, give the Acidum Nitrohydro- 
chloricum Dilutum. 

2HNO ? + 6HC1 = N 2 2 C1 4 ? + 4H 2 + Cl 2 

Nitric acid. Hydrochloric Chloronitric Water. Chlon'ue. 

acid. gas. 

In the later stages of the reaction, the decomposition expressed in 
the following equation also probably occurs : — 

HNO3 + 3HC1 = NOC1 + 2H 2 + Cl 2 

Nitric acid. Hydrochloric Chlorouitrous Water. Chlorine, 

acid. gas. 

The same reaction occurs if the acids are mixed after dilution, but 
is not complete for a week or a fortnight (Tilden). The undiluted 
mixture of acids is known as aqua regia, so called from its property 
of dissolving gold, "the king" of metals. 

This "diluted nitrohydrochloric acid" is quite strong enough to 
attack organic matter, with evolution of nitrous gases, hence should 
not be dispensed with tinctures, etc. without further dilution. 

Analytical Reactions ( Tests'). 

First Analytical Reaction. — To a solution of any nitrate 
(e.ff-, KNO3) add sulphuric acid, and then copper turnings, and 
warm ; colorless nitric oxide gas (NO) is evolved, which at 
once unites with the oxygen in the tube, giving red /anus of 
nitric peroxide or peroxide of nitrogen (N0 2 ). 

2KN0 3 + 5H 2 S0 4 + Cu 3 = 2NO + 3CuS0 4 + 4H 2 + 2KHS0 4 ; 
then, 2NO + 2 = 2N0 2 . 

Performed on a larger scale, in a vessel to which a delivery-tube 
is attached, the reaction of nitric acid on copper becomes of synthet- 
ical interest, being the process for the preparation of nitric oxide gas 
for the purposes of chemical experiment. 

Small amounts of a nitrate may be overlooked by this test, the 
color of the red fumes not being very intense. 

Undiluted nitric acid poured on to copper turnings gives dense red 
vapors of nitrous acid (LINO.,), nitrous anhydride (X.,0..), nitric 
peroxide (N0 2 ), nitric oxide (NO), and even nitrogen (N..). the re- 



288 SALTS OF ACIDULOUS RADICALS. 

action varying somewhat according to the temperature of the mix- 
ture and (Ackworth) the amount of nitrate of copper in solution. 
Diluted nitric acid gives nitric oxide, Cu 3 -f- 8HN0 3 = 3(Cu2NO 
4- 4H 2 + 2NO. 

Second Analytical Reaction. — To a cold solution of the ni- 
trate, even if very dilute, add three or four crystals of sul- 
phate of iron, shake gently for a minute in order that some of 
the sulphate may become dissolved, and then pour eight or ten 
drops of strong sulphuric acid down the side of the test-tube, 
so that it may form a layer at the bottom of the vessel ; a 
reddish-purple or black coloration will appear between the acid 
and the supernatant liquid. 

This is a very delicate test for the presence of nitrates. The black 
color is due to a solution or, perhaps, combination of nitric oxide 
with a portion of the ferrous salt. The nitric oxide is liberated 
from the nitrate by the reducing action of the hydrogen of the 
sulphuric acid, the sulphuric radical of which is absorbed by the 
ferrous sulphate, the latter salt becoming ferric sulphate. 
2HN0 3 + 3H 2 S0 4 + 6FeS0 4 = 4H 2 + 3(Fe 2 3S0 4 ) + 2NO. 

The process of oxidation is one frequently employed in experi- 
mental chemistry ; and nitrates, from their richness in oxygen, but 
more especially because always at hand, are the oxidizers usually 
selected for the purpose. In the operation they generally split up in 
one way, namely, into oxide of their basylous radical, nitric oxide 
gas, and available oxygen. Thus hydrogen nitrate (nitric acid) 
yields oxide of hydrogen (water) and the other bodies mentioned, 
as shown in the following equation : — 

4HN0 3 = 2H 2 + 4NO + 30 2 . 

When nitrates, other than nitric acid, are used for the purpose of 
oxidation, a stronger acid, generally sulphuric, is commonly added in 
order that nitric acid may be formed ; the hydrogen nitrate splitting 
up more readily than other nitrates. 

The jive oxides of nitrogen have now been mentioned, namely — 

Nitrous oxide . . 

Nitric oxide* . . 

Nitrous anhydride 

Nitric peroxide* . 

Nitric anhydride . 
Nitrous oxide is a colorless gas not altered by exposure to air ; 
nitric oxide is also colorless, but gives red fumes in the air ; nitrous 
anhydride is a red vapor condensible to a blue liquid ; nitric peroxide 
is a red vapor condensible to an orange liquid ; nitric anhydride is a 
colorless crystalline solid. The two anhydrides by absorbing water 
yield respectively nitrous acid (HN0 2 ) and nitric acid (HN0 3 ). 

* The specific gravities of these gases indicate that NO and N0 2 are 
the correct formulae, and not N 2 2 and N 2 4 . 



NITRATES. 289 

Nitrous oxide is also probably an anhydride, the acid of which would 
doubtless have the formula HNO, while the silver and sodium salts 
certainly have the formulae AgNO and NaNO,3H 2 (Divers ; Menke). 
The above series of compounds forms a good illustration of the doc- 
trine of multiple proportions (p. 51). 

Third Analytical Reaction. — Direct the blowpipe-flame on 
to charcoal until a spot is red hot ; now place on the spot a 
fragment of nitrate ; deflagration ensues. 

This reaction does not distinguish nitrates from chlorates. It is 
insufficient for the recognition of very small quantities of either class 
of salts, especially when they are mixed with other substances. 

Gunpowder is an intimate mechanical mixture of 75 parts of nitre, 
15 to 12J parts of charcoal, and 10 to 12J parts of sulphur. In burn- 
ing it may be said to give sulphide of potassium (the white smoke), 
(K 2 S), nitrogen (N), carbonic oxide (CO), and carbonic acid (C0 2 ) 
gases, though the decomposition is seldom complete. The sudden 
production of a large quantity of heated gas from a small quantity of 
a cold solid is sufficient to account for all the effects of gunpowder. 

Fourth Analytical Reaction. — To nitric acid or other nitrate 
add solution of " sulphate of indigo ;" the color is discharged. 

Test-Solution of Indigo. U. S. P. (Sulphindylic or Sulphindigotic 
acid), is made by digesting 1 part of dry, finely powdered indigo in 
12 parts of strong sulphuric acid in a test-tube for an hour, the 
mixture being kept hot by a water-bath ; the blue liquid is then 
poured into 500 parts of sulphuric acid, the whole well shaken, set 
aside, and the clear liquid decanted. Free chlorine also destroys 
the color of this reagent. 

Indigo, U. S. P. (C 8 H 5 NO), is a blue coloring-matter deposited 
when infusion of various species of Indigofera is exposed to air and 
slight warmth. Under these circumstances indican, a yellow trans- 
parent amorphous substance, soluble in water, breaks up into indigo, 
which is insoluble and falls as a sediment, and a sort of sugar termed 
indiglucin. The indigo is collected, drained, pressed, and dried. 
By action of deoxidizing agents indigo is converted into soluble 
colorless indigogen, reduced indigo or white indigo (C 8 H 6 NO) ; 1 
part of powdered indigo, 2 of green sulphate of iron, 3 of slaked 
lime, and 200 of water, shaken together and set aside in a well- 
closed bottle, give this colorless indigo. A piece of yarn, calico, or 
similar fabric dipped into such a solution, and exposed to air, lie- 
comes dyed blue, deposition of insoluble indigo-blue occurring 
within the cells and vessels of the fibre. This operation is readily 
performed on the small scale, and forms a good illustration of the 
characteristic feature of the art of dyeing, namely, the introduction 
of soluble coloring-matter into a fabric by permeation of the walls 
of its cellular and vascular tissue, and the imprisonment of that 
Coloring-matter by conversion into a solid and insoluble form {ride 
also p. 138). 

Pure indigo, or indigotin, may be obtained in beautiful needles by 



2*90 SALTS OF ACIDULOUS RADICALS. 

spreading a paste of indigo and plaster of Paris on a tin plate, and 
when quite dry placing a lamp underneath, moving the latter from 
place to place as the indigo sublimes and condenses on the surface 
of the plaster. It may also be obtained in crystals by gently boiling 
finely-powdered indigo with aniline, filtering while hot, and setting 
aside ; these crystals may be washed with alcohol. Hot paraffin may 
be employed instead of aniline. It is possible to obtain indigotin 
artificially ; indeed, Baeyer states that indigo can be made econom- 
ically from toluene. 

Distinction between Nitric Acid and other Nitrates. — Presence of 
the nitric radical in a solution having been proved by the above re- 
actions, its occurrence as the nitrate of a metal is demonstrated by 
the neutral, or nearly neutral, deportment of the liquid with test- 
paper and the detection of the metal, its occurrence as nitric acid 
by the sourness of the liquor to the taste and the effervescence pro- 
duced on the addition of a carbonate. 

Antidote. — In cases of poisoning by strong nitric acid, solution of 
carbonate of sodium (common washing soda) or a mixture of mag- 
nesia and water may be administered as antidotes. 



QUESTIONS AND EXERCISES. 

444. Trace the origin of nitrates. 

445. In whatdoes cubic nitre differ, chemically, from prismatic nitre? 

446. Describe a process by which nitrate of potassium may be 
obtained artificially. 

447. State the difference between nitrate of potassium, nitre, salt- 
petre, and sal prunella. 

448. What group of elements is characteristic of all nitrates ? and 
what claim has this group to the title of radical ? 

449. Mention the usual theory regarding the manner in which 
atoms are arranged with reference to each other in such salts as 
nitrate of potassium. 

450. How is Nitric Acid prepared ? 

451. Give the properties of nitric acid. 

452. What reactions occur when strong nitric and hydrochloric 
acids are mixed ? 

453. How is nitric oxide prepared? 

454. Enumerate and explain the tests for nitrates. 

455. Into what substances does nitric acid usually split when em- 
ployed as an oxidizing agent? 

456. How is nitrous oxide prepared? 

457. Enumerate the five oxides of nitrogen. 

458. What is the nature of gunpowder? 

459. Write a few sentences on the chemistry of indigo, one of the 
tests for nitric acid. 

460. How is nitric acid distinguished from other nitrates ? 

461. What quantity of cubic nitre will be required to produce ten 
carboys of official nitric acid, each containing 114 pounds? — Ans. 
1076| pounds. 



CHLORATES. 291 

CHLORIC ACID AND OTHER CHLORATES. 

Formula of Chloric Acid HC10 3 . Molecular weight 84.4. 
Chlorates are made from hypochlorites. 

Hypochlorous Acid (HCIO) and other Hypochlorites. 

Place a few grains of red oxide of mercury in a test-tube, 
half fill the tube with chlorine- water, and well shake the mix- 
ture ; the resulting liquid is a solution of hypochlorous acid, 
mercuric oxychloride remaining undissolved : 

2HgO + 2C1 2 + H 2 = HCIO + Hg 2 OCl 2 . 

By the metathesis (double decomposition) of hypochlorous 
acid and oxides or hydrates, other pure hypochlorites are 
formed : — 

HCIO + NaHO = NaCIO + H 2 0. 

The direct action of chlorine on metallic hydrates and some 
carbonates is supposed to give a mixture of chloride and hypo- 
chlorite, as described in connection with the synthetical reac- 
tions of Calcium (p. Ill, Calx Chlorata, U. S. P.) 

Cl 2 + 2NaHO = NaCl,NaC10 + H 2 0; 
2C1 2 + 2CaH 2 2 = CaCl 2 ,Ca2C10 + 2H 2 0. 

The condition of chlorides in these bodies is not satisfactorily 
made out; so that their constitution is not definitely deter- 
mined. The action of acids on them results in the evolution 
of chlorine ; hence the great value of the calcium compound 
(chlorinated lime, or chloride of lime) in bleaching opera- 
tions : — 

CaCl 2 ,Ca2C10 + 2H 2 S0 4 = 2C1 2 + 2CaS0 4 + 2H 2 0. 
The solubility of hypochlorites in water, their peculiar odor, 
greatly intensified on the addition of acid, and their bleaching 
powers (see the above Calcium reaction) are the characters on 
which to rely in searching for hypochlorites. 

Chlorates. 

The group of elementary atoms represented by the formula CIO., 
is that characteristic of chloric acid and all other chlorates ; hence it 
is expedient to regard it as being an acidulous radical, which may be 
termed the chloric radical. Like the nitric radical, it has not been 
isolated. Chloric anhydride (ULjOg), unlike nitric anhydride, has not 
yet been obtained in the free condition. 

Chlorates are artificial salts. They are formed by simply boiling 
aqueous solution of the common bleaching salts (chlorinated lime, 
chlorinated soda, chlorinated potash). Heat thus converts 



292 SALTS OF ACIDULOUS RADICALS. 

3(NaCl, NaCIO) ) < f NaC10 s ] f 5NaCl 

Chlorinated soda. >• into < Chlorate of >• and 



3(KC1, KC10) ] f KCIO3 I f 5KC1 

Chlorinated } into 1 Chlorate > and < Chloride of 

potash. I i of potassium. I I potassium. 

3(CaCl 2 , Ca2C10) ] f Ca2C10 3 ] ( 5CaCl 2 

Chlorinated > into < Chlorate of > and 

lime. calcium. 

One chlorate may also be made from another by double decomposi- 
tion. In making chlorates economically the chlorinated salt is, of 
course, at once converted into chlorate. 

Chlorate of Potassium. 

Thus Chlorate of Potassium (Potassii Chloras, U. S. P.) is 
commercially made by saturating with chlorine gas a moistened 
mixture of three parts of chloride of potassium and ten of 
slaked lime, and well boiling the product. Chlorinated lime is 
first formed ; this, on continued boiling with water, splits up 
into chloride of calcium and chlorate of calcium, and the latter, 
reacting on the chloride of potassium, yields chloride of calcium 
and chlorate of potassium. 

6(Ca2HO) + 6C1 2 = 3(CaCl 2 ,Ca2C10) + 6H 2 ; 

3(CaCl„Ca2C10) = Ca2C10 3 + 5CaCl 2 ; 

Ca2C10 3 + 2KC1 = CaCl 2 + 2KC10 3 . 
This operation may be conducted on a small scale by rubbing 
together in a mortar the above proportions of ingredients in 
ounces or half ounces, adding enough water to make the whole 
assume the character of damp lumps, placing the porous mass 
in a funnel (loosely plugged with stones or pieces of glass), 
and passing chlorine gas (p. 27) through the mass by attaching 
the tube delivering the gas to the neck of the funnel. When 
the whole mass has become of a slight pink tint (due to a trace 
of permanganate), it should be turned into a dish, icell boiled 
with water, filtered, the filtrate evaporated if necessary, and 
set aside ; the chlorate of potassium crystallizes out in color- 
less rhomboidal plates, chloride of calcium remaining in the 
mother-liquor. 

In the official process carbonate of potassium is alluded to as 
being used in place of the chloride ; but otherwise the method is simi- 
lar to that just described. Chlorinated potash and chlorinated lime 
are first formed : — 

K 2 C0 3 + Ca2HO + Cl 2 = KC1,KC10 + CaC0 3 + H 2 0, 
6(Ca2HO) + 6C1 2 = 3(CaCl 2 ,Ca2C10) + 6H 2 : 



CHLORATES. *VO 

these, on boiling with water, spilt up into chlorates and- chlorides — 

3(KC1,KC10) = KCIO3 + 5KC1, 
3(CaCl 2 ,Ca2C10) = Ca2C10 3 + 5CaC! 2 ; 

the whole of the chloride of potassium and chlorate of calcium finally 
yielding chlorate of potassium and chloride of calcium — 

2KC1 + Ca2C10 3 = CaCl 2 + 2KC10 3 . 

Neglecting intermediate decomposition, the reactions may be repre- 
sented by the following equation : 

6C1 2 + K 2 C0 3 + 6CaII 2 2 = 2KC10 3 + CaC0 3 

Chlorine. Carbonate of Hydrate of Chlorate of Carbonate of 

potassium. calcium. potassium. calcium. 

+ 5CaCl 2 + 6H 2 

Chloride of Water, 

calcium. 

Chlorate of Sodium (Sodii C Moras, U.S.P.), NaC10 3 , is similarly 
prepared. 

Chlorate of potassium is soluble in water to the extent of 6 or 7 
parts in 100 at common temperatures. It must on no account be 
rubbed with sulphur or sulphides in a mortar or otherwise, friction 
of such a mixture resulting in violent explosion. 

Chlorate of potassium, when heated, yields chloride of potassium 
and oxygen, and is the salt commonly employed in the preparation 
of the gas for experimental purposes. But if the action be carried 
on at as low a temperature as possible, and be arrested when 100 
parts of the chlorate have (Teed) yielded 7.84 parts of oxygen, the 
residual salt will be found to contain only perchlorate of potassium 
(KC10 4 ), and chloride 10KClO 3 = 6KC10, + 4KC1 + 30 2 ; a higher 
temperature causes decomposition of the perchlorate, KCIO^ == KC1 
+ 20 2 . When the chlorate is heated with peroxide of manganese, 
no perchlorate is formed. 

Perchloric Acid (HC10 4 ). — Crude perchlorate of potassium, ob- 
tained as just indicated, is boiled (in a fume-cupboard) with hydro 
chloric acid to decompose any chlorate that may be remaining, and 
then separated from chloride by washing and crystallization, chloride 
being far more soluble in water than the perchlorate. Perchloric 
acid is then obtained by distilling the perchlorate of potassium with 
sulphuric acid ; it is quite stable, and is occasionally administered in 
medicine. 

Chloric^ Acid (HC10 3 ) may be isolated, but is unstable, quickly 
decomposing into chlorine, oxygen, and perchloric acid ; some other 
chlorate {e. g., KC10 3 ) must therefore be used in studying the reac- 
tions of the chloric radical. 



294 SALTS OF ACIDULOUS RADICALS. 

Table of the Chlorine Acids. 

Hydrochloric acid .... HC1. 

Hypochlorous acid .... HCIO. 

Chlorous acid HC10 2 . 

Chloric acid HC10 3 . 

Perchloric acid HC10 4 . 

The chloric radical is univalent (C10 3 ). The acidulous radicals 
of the other chlorine acids are also univalent, as indicated in the 
foregoing formulae. 

Analytical Reactions (Tests'). 

First Analytical Reaction. — To solution of a chlorate (p. gr., 
chlorate of potassium) add solution of nitrate of silver ; no pre- 
cipitate falls, showing that the chlorine must be performing 
different functions from those it possesses in chlorides. Evap- 
orate the solution to dryness, and place the residue in a small 
dry test-tube, or at once drop a fragment of a chlorate into a 
test-tube, and heat strongly ; oxygen is evolved, and may be 
recognized by its power of re-inflaming an incandescent match 
inserted in the tube. Boil the residue with water, and again 
add solution of nitrate of silver ; a white precipitate falls, hav- 
ing all the characters of chloride of silver, as described under 
Hydrochloric Acid. 

This is a trustworthy test, and, even omitting the recognition of 
the oxygen, may be applied in the detection of small quantities of 
chlorates. 

Second Analytical Reaction. — To a fragment of a chlorate 
add two or three drops of strong sulphuric acid ; an explosive 
gas (C1 2 4 ) is evolved, somewhat resembling chlorine in odor, 
but possessing a deeper color than that element. 

3KC10 3 4- H 2 SO, = CIA + KC10 4 + K 2 S0 4 + H 2 0. 

Warm the upper part of the test-tube to 150° or 200° F., or 
introduce a hot wire ; a sharp explosion ensues, due to decom- 
position of the gas, peroxide of chlorine, into its elements. 

Third Analytical Reaction. — Heat a small fragment of a 
chlorate with hydrochloric acid : a yellowish-green explosive 
gas termed euchlorine is evolved. Its color is deeper than that 
of chlorine, hence the name (from eZ, eu, well, and yXwpoq, 
chloros, green). In odor it resembles chlorine, and is probably 
a mixture of that element with one of the oxides of chlorine. 

Fourth Analytical Reaction. — Direct the blowpipe-flame on 
to charcoal until a spot is red hot, and then place on the spot 
a fragment of a chlorate ; deflagration ensues as with nitrates. 



IODATES. 295 

Bromates. 

Bromates are salts closely resembling chlorates and iodates. The 
formula of Bromic Acid is HBr0 3 . The presence of bromates in 
bromides is shown by the production of a yellow color on addition 
of diluted sulphuric acid, 5KBr + KBr0 3 + 3H 2 S0 4 = 3K 2 S0 4 + 
3H 2 + 3Br 2 , 

Iodates. 

Iodic Acid (HI0 3 ). — Iodine is boiled in a flask with five times its 
weight of the strongest nitric acid (sp. gr. 1.5), in a fume-cupboard, 
until all action ceases. On cooling, iodic acid separates in small 
pyramidal crystals. These are removed, the residual liquid evapor- 
ated to dryness to remove excess of nitric acid, the residue and the 
first crop dissolved in a small quantity of boiling water, and the 
solution set aside to crystallize. 

Iodate of Potassium (KI0 3 ). — Powder together equal weights of 
iodine and chlorate of potassium ; to the mixture add twice its weight 
of water and about one-eighth of its weight of nitric acid ; warm the 
whole until iodine disappears, and evaporate quite to dryness over a 
water-bath. The residue dissolved in water forms the reagent " Solu- 
tion of Iodate of Potassium." It contains a little nitrate of potassium. 

In this reaction the small quantity of nitric acid furnishes corre- 
sponding amounts of nitrate of potassium and chloric acid. The 
chloric acid with iodine gives iodic acid and chlorine, thus : — 

2HC10 3 + I 2 = 2HI0 3 + Gl 2 . 

The iodic acid and some chlorate of potassium then yield chloric acid 
and iodate of potassium — 

HI0 3 -f KCIO3 == HC10 3 + KI0 3 ; 

and the two reactions alternate until the whole of the iodine has dis- 
placed the whole of the chlorine. 

Iodate of potassium and sulphurous acid decompose each other 
with elimination of iodine (or with formation of a blue color, if starch 
be present.) Sulphurous acid occurring as an impurity in acetic and 
other acids may thus be detected. 

2KI0 3 + 5H 2 S0 3 = I 2 + 3H 2 S0 4 + 2KHS0 4 + H 2 0. 

If iodic acid solution be mixed with mucilage of starch, and solu- 
tion of sulphuretted hydrogen be added, a blue zone is formed at the 
junction of the liquids. 

Ferric iodate, or rather Oxyiodate (Fe 2 04IO.„8ILO), is precipi- 
tated on adding solution of ferric chloride to solution of iodate of 
potassium. 

QUESTIONS AND EXERCISES. 

462. How may hypochlorous acid be formed ? 

463. What are the relations of hypochlorous acid to common 
bleach mg-powder ? 

25* 



296 SALTS OF ACIDULOUS RADICALS. 

464. By what reaction is chlorine eliminated from hypochlorites ? 

465. State the general reaction by which chlorates are formed. 

466. Give details of the preparation of chlorate of potassium. 

467. Mention the properties of chlorate of potassium. 

468. What decompositions occur when chlorate of potassium is 
heated ? 

469. Find the molecular weight of chlorate of potassium. 

470. What weight of oxygen is yielded when 1 oz. of chlorate of 
potassium is completely decomposed, and how much chloride of 
potassium remains? 

471 . One hundred cubic inches of oxygen, at 60° F. and barometer 
at 30 inches, weighing 34.203 grains, and 1 gallon containing 277} 
cubic inches, what weight of chlorate of potassium will be required 
to yield 10 gallons of the gas? Ans. 5^ ounces. 

472. How many cubic inches of oxygen are producible from 1 oz. 
of chlorate of potassium? 

473. Calculate the weight of chlorate of potassium theoretically 
obtainable from 100 parts of chloride. 

474. How is perchloric acid prepared ? 

475. Enumerate the chlorine acids. 

476. How may the presence of chlorides in chlorates be demon- 
strated ? 

477. Mention the tests for chlorates. 

478. Give the formula of peroxide of chlorine. 

479. What is euchlorine ? 

480. How may iodic acid be made ? 

481. Describe the preparation of iodate of potassium. 



ACETIC ACID AND OTHER ACETATES. 

Formula of Acetic Acid HC 2 H 3 0. 2 . Moleeular weight 60. 

Source. — Acetic acid is said to occur naturally in certain plant 
juices and animal fluids in minute proportions, but otherwise is an 
artificial product. Much is furnished by the destructive distillation 
of wood, hence the term pyroligneous acid for the crude product, a 
hybrid word from irvp, pur, fire, and lignum, wood. This impure 
product, neutralized by carbonate of sodium, the whole evaporated, 
and the residue gently heated to drive off the volatile tarry matters, 
gives acetate of sodium, which after recrystallization furnishes by 
distillation with oil of vitriol and water acetic acid in a fair state of 
purity. In Germany and France large quantities of acetic acid are 
made' by the spontaneous oxidation of the alcohol in inferior wines, 
in the presence, according to Pasteur, of a plant-ferment termed 
Mycoderma aceti (the Bacterium mycodermi of Cohn); hence the 
white- and red-wine vinegar {vinegar, from the French vin, wine, and 
aigre, sour). Indeed this bacterium may be propagated, and the 
artificial manufacture of vinegar from alcohol and water be carried 
out, by its acid, on a large scale. In England also the domestic 
form of acetic acid (brown vinegar) has a similar origin ; infusion of 



ACETATES. 297 

malt and unmalted grain is fermented, and the resulting oxidation 
of its sugar, instead of being arrested when the product is an alco- 
holic liquid, a sort of beer, is allowed to go on to the next stage, 
acetic acid ; it usually contains from 3 to 6 per cent, of real acetic 
acid (HC 2 H 3 2 ). 

Vinegars. — Ordinary brown vinegar contains about 5£ per cent. 
of acid. The so-called Vinegar of Cantharides {Acetum Cantharidis, 
B. P.) is a solution of the active principle of cantharides in very 
strong acetic acid, not in vinegar. The Vinegar of Squill {Acetum 
Settles, U. S. P.) is also a solution of the active principle of squill in 
diluted acetic acid, not in true vinegar. The same may be said of 
Acetum Lobelice, U. S. P., and Acetum Sanguinarice, U. S. P. (Vin- 
egar of Blood-root). The Acetum Opii, U. S. P., or Black Drop of 
America, is made from nutmeg, saffron, and sugar, as well as Opium 
and Diluted Acetic Acid. 

Tlie Acetic Radical. — The group of elements represented by the 
formula C 2 H 3 2 is that characteristic of acetic acid and other ace- 
tates, and may, for the convenience of study, be assumed to be an 
acidulous univalent radical. But different strengths are sold under 
certain numbers which in the United States refer to the number of 
grains of bicarbonate of sodium neutralized by 1 fluidounce (wine 
measure), and in Great Britain refer to the number of grains of an- 
hydrous carbonate of sodium neutralized by 1 Imperial fluidounce. 

Acetyl. — The characteristic grouping in acetates, C 2 H 3 2 , is fre- 
quently considered to contain, rather than to be, a radical — C 2 II 3 0, 
termed acetyl. Acetates yield a body having the composition 
C 2 II 3 0C1, which is regarded as chloride of acetyl ; from this may be 
obtained- acetic anhydride (C 4 H 6 3 ), which by absorbing water be- 
comes acetic acid. 

C 2 H 3 ) C 2 H 3 } Q C 2 H 3 ) Q C 2 H 3 } 

01/ C 2 H 3 0j U HJ U M'j U 

Chloride of Acetic Acetic acid. Metallic 

acetyl. anhydride. acetates. 

The relation of acetic acid to alcohol will be evident from the fol- 
lowing equation representing empirically the formation of the acid : — 

C 2 H c O + 2 = 2 H 4 O 2 + H 2 0. 

Alcohol. Acetic acid. 

_ Acetates in aqueous solution are liable to decomposition. In solu- 
tionof acetate of morphine a myceloid growth occasionally forms, 
acetic acid disappears, and morphine is deposited. Solution of ace- 
tate of ammonium is liable to a similar change, gradually becoming 
alkaline. 

Synthetical Reaction. 

- Acetic Acid. 

Synthetical Reaction. — To a few grains of acetate of sodium 

in a test-tube add a little water and some sulphuric acid, and 
heat the mixture; acetic acid is evolved, and may be eon- 



298 SALTS OF ACIDULOUS RADICALS. 

densed by a bent tube adapted to the test-tube by a cork in tbe 
usual way. 

Acetic Acid. — This is the process by which acetate of sodium or 
calcium (the neutralized products of the distillation of wood) is made 
to yield acetic acid on the large scale. As with nitric and hydro- 
chloric acids, the loose term "acetic acid" is that usually applied to 
aqueous solutions of acetic acid. The Acidum Aceticum, U. S. P., 
contains 36 per cent, of real acid, that is, of HC,H 3 2 ; for it con- 
tains only 30.6 per cent, of acetic anhydride (C 4 H 6 3 ) — still occa- 
sionally though somewhat obscurely termed anhydrous acetic acid. 
Its specific gravity is 1.048. Acidum Aceticum Dilutum. U. S. P., 
contains 6 per cent, of HC 2 H 3 2 . Sp. gr. 1.0083. Glacial acetic 
acid (HC 2 H 3 2 ) contains no water. It solidifies to a crystalline mass 
at and below 15° C. (59° F.). hence the appellation glacial (from gla- 
des, ice). Sp. gr. from 1.056 to 1.058. Good commercial glacial 
acetic acid (Acidum Aceticum Glaciate, U. S. P.) does not contain 
more than 1 per cent, of water. Although water is lighter than this 
acetic acid, yet the addition of Avater at first renders the acid heavier ; 
evidently, therefore, condensation or contraction in bulk occurs on 
mixing the liquids : after 10 per cent, has been added, the addition 
of more water produces the usual effect of dilution of a heavy liquid 
by a lighter — namely, reduction of relative weight. This matter will 
be better understood after the subject of specific gravity has been 
studied. 

The following equation is expressive of the foregoing reaction : — 



XaC,H 3 2 - 


- H.,S0 4 -- 


= HC 2 H 3 2 


- XaHSO, 


Acetate of 


Sulphuric 


Acetic acid. 


Acid sulphate 


sodium. 


acid. 




of sodium. 



or, assuming the existence of acetyl (C 2 H 3 0) in acetic acid, and a 
corresponding radical sulphuryl (S0 2 ) in sulphuric acid — 

C 2 H s O 1 n SO., 1 n C.,H 3 ) n , SO., 1 n 

or. thirdly, on the assumption that salts contain the oxide of a basy- 
lous radical united with the anhydride of an acid (the old view under 
which such names as acetate of soda were formed) — 

Xa.O.C.HA -r 2H 2 0,S0 3 = Xa 2 0,H 2 0,2S0 3 -J- H 2 O.C 4 H 6 3 . 

Note on the Constitution of Salts. 

"Which of these three equations, or. more broadly, which of the 
three views of the constitution of salts illustrated by the equations, 
is correct, it is impossible to say. "Whether it is'C 2 H 3 2 . C.,H 3 0. 
or C 4 H 6 3 , which migrates from one acetic compound to another, 
whether it is S0 4 . S0 2 , or S0 3 . which migrates from one sulphuric 
compound to another, and so on with other acidulous groupings, 
cannot at present be determined. There are strong objections to 
each view ; and possibly neither is right. Either the given radicals 
cannot be isolated, or application of the forces of heat, light, and 
electricity do not confirm views arrived at by the results of opera- 



ACETATES. 299 

tions with the chemical force; or a salt comes "to be regarded as 
having so large a number of constituent parts that the view, how- 
ever true, breaks down in practice from the sheer inability of the 
student to grasp the complicated analogies involved. Yet for the 
purposes of description, study, and conversation some system must 
be adopted. Let the first, then, be generally taken for the present, 
over-reliance on it being checked by the use of general instead of 
special names for the hypothetical radicals, and other systems be 
employed in other cases. 

Analytical Reactions (Tests). 

First Analytical Reaction. — To an acetate add sulphuric 
acid and heat the mixture ; acetic acid, recognized by its odor, 
is evolved. 

Note 1. — Iodine, sulphurous acid, and other substances of power- 
ful odor, mask that of acetic acid ; they must be removed, therefore, 
usually by precipitation or oxidation, before applying this test. 

Note 2. — It will be noticed that this reaction is identical with the 
previous one ; it has synthetical or analytical interest, according to 
the object and method of its performance. 

Second Analytical Reaction. — Repeat the above action, a few 
drops of spirit of wine being first added to the acetate ; acetic 
ether (acetate of ethyl, C 2 H 5 C 2 H 3 2 ), also of characteristic 
odor, is evolved. 

The basylous radical ethyl (C 2 H 5 ) will be referred to subsequently. 

Third Analytical Reaction. — Heat a fragment of a dry ace- 
tate in a test-tube, and again notice the odor of the gaseous 
products of the decomposition ; among them is acetone (C 3 H 6 0), 
the smell of which is characteristic. Carbonate of the metal 
remains in the test-tube. 

Fourth Analytical Reaction. — To a solution of an acetate 
made neutral by the addition of acid or alkali, as the case may 
be, add a few drops of neutral solution of perchloride of iron ; 
a deep-red liquid results, owing to the formation of ferric 
acetate (Fe 2 6C 2 H 3 2 ). Boil ; a precipitate of oxyacetate of 
iron occurs, leaving the liquid colorless. Strong acids also 
decompose ferric acetate. 

Analytical Note. — It will be noticed that the formation of cha- 
racteristic precipitates, the usual method of removing radicals from 
solution for recognition, is not carried out in the qualitative analysis 
of acetates. This is because all acetates are soluble. Acetate of 
silver (AgC 2 H 3 2 ) and mcrcurous acetate (llgl\,ll ;! 0.,) are only spar- 
ingly soluble in cold water, but the fact can seldom be utilized in 
analysis. Hence peculiarities of color and odor, the next best cha- 
racters on which to rely, are adopted as means by which acetates 



300 SALTS OF ACIDULOUS RADICALS. 

may be detected. ' Acetates, like other organic compounds, char 
when heated to a high temperature. 

Note on Anhydrides. — Up to this point the student has regarded 
an anhydride as a body derived from an acid by removal of the 
whole of the hydrogen of the acid, together with as much of its oxy- 
gen as with the hydrogen forms water. The definition will scarcely 
apply to acetic anhydride, and must therefore be somewhat qualified. 
An anhydride is derived from an acid, the acid having lost the whole 
of its basylous hydrogen and so much oxygen as is necessary to form 
water with that hydrogen. Anhydrides are obtained by heating 
acids, and by other methods. 



QUESTIONS AND EXERCISES. 

482. What is the formula of acetic acid ? 

483. State the relation of acetic acid to other acetates. 

484. What is the molecular weight of acetic acid ? 

485. Name the sources of acetic acid. 

486. What is pyroligneous acid ? 

487. From what compound is the acetic acid of foreign and Eng- 
lish vinegar immediately derived ? 

488. How much real acid is contained in official vinegar? 

489. What is the nature of the "Vinegars" of Pharmacy? 

490. How may acetic acid be obtained from acetate of sodium ? 

491. Hoav much real acid is contained in the official acetic acid? 

492. Mention the strength of commercial glacial acetic acid. 

493. Give three or more views of the constitution of acetates, illus- 
trating each by formulae. 

494. Enumerate the tests for acetates. 



HYDROSULPHTJRIC ACID AND OTHER SULPHIDES. 

Formula of Hydrosulphuric Acid H 2 S. Molecular weight 34. 

Source and Varieties of Sulphur. — The acidulous radical of hydro- 
sulphuric acid, sulphydric acid, or sulphuretted hydrogen, and other 
sulphides, is the element sulphur (S). It occurs in nature in combi- 
nation with metals, as already stated in describing the ores of some 
of the metals, and also in the free state. Most of the sulphur used 
in medicine is imported from Sicily, where it occurs chiefly associated 
with blue clay. It is purified by fusion, sublimation, or distillation. 
Melted and poured into moulds, it constitutes a crystalline mass 
termed roll sulphur. If distilled and the vapor carried into large 
chambers, so that it may be rapidly condensed, the crystals are so 
minute as to give- the sulphur a pulverulent character ; this is sub- 
limed sulphur {Sulphur Sublimatum, U. S. P.) or flowers of sulphur: 
the same washed with dilute ammonia, to remove the traces of sul- 
phuric acid (often 0.1 per cent., resulting from very slow oxidation 
in ordinary moist air), or, possibly, arsenious sulphide, constitutes 
Sulphur Lotum, U. S. P. 

The third common form, milk of sulphur, will be noticed subse- 



SULPHIDES. 301 

quently. Sulphur also occurs in nature in combination as a constit- 
uent of animal and vegetable tissues, as sulphurous acid gas (S0 2 ) 
in volcanic vapors, and as sulphuretted hydrogen in some waters, as 
those of Harrogate. 

Plastic sulphur is one of the allotropic varieties of the element, 
obtained on heating sulphur considerably beyond its melting-point 
and pouring into cold water. 

Quantivalence. — Sulphur is sexivalent, as seen in sulphuric anhy- 
dride (S0 3 ), a substance which will be noticed under sulphuric acid. 
It also occasionally exhibits quadrivalent (S0 2 ) and still oftener biv- 
alent affinities (H 2 S). 

Molecular Weight. — At very high temperatures sulphur follows 
the rule that, under similar conditions of heat and pressure, atomic 
weights (in grammes, grains, etc.) of volatile elements occupy equal 
volumes of vapor ; its formula therefore is S 2 , and molecular weight 
64. At lower temperatures the volume weighs three times as much 
as it should do if following usual laws, and then the molecule would 
appear to contain six atoms (S 6 ). 

Acid Salts. — Sulphur (S 7/ ) being the first acidulous radical of 
bivalent activity met with in these sections on acids, it is desirable 
here to draw attention to a new class of salts to which such a rad- 
ical will generally give rise. These are acid salts, which are inter- 
mediate between normal salts and acids. Univalent radicals with an 
atom of hydrogen give an acid, and with an atom of other basylous 
radicals an ordinary or normal salt. But bivalent radicals, from the 
fact that they give with two atoms of hydrogen an acid, and with 
two atoms of univalent metals a normal salt, may obviously give 
intermediate bodies containing one atom of hydrogen and one 
atom of metal : these are appropriately termed acid salts : they are 
neither normal acids nor normal salts, but acid salts. (Examples : 
KIICO3, NaHS0 4 , KHC 4 H 4 6 , Na 2 HP0 4 , CuHAs0 3 , CaH 4 2PO,.) 
Whether or not these salts give an acid reaction with blue litmus- 
paper depends on the strength of the respective radicals. Usually 
they do redden the test-paper, but sometimes not ; thus the acid sul- 
phide or sulphydrate of potassium (KHS), of sodium (NaHS), or 
ammonium (N1IJIS) has alkaline properties.* 

The chemical analogy between sulphur and oxygen, already once 
alluded to (p. 173), is further illustrated by the compounds just 
mentioned. Sulphur is also closely related to the rarer element 
Selenium. Thus we have Se0 2 as well as S0 2 , H 2 Se0 3 (selenious 
acid) as well as II 2 S0 8 (sulphurous acid), H 2 Se0 4 (selcnic acid), as 
well as II 2 S0 4 (sulphuric acid). The rare element Tellurium also 
seems to have similar analogies. The four hydrogen compounds of 
the group have the formula) H 2 0, 1I 2 S, Il 2 Se, H 2 Te. {Vide Index, 
" Periodic Law.'') 

* Chemists regard these sulphydrates as compounds of basylous rad- 
cals with MS, a univalent grouping termed hydrosulphyl (persulphide 
of hydrogen, H 2 S 2 ), just as hydrates are similarly viewed as compounds 
of the univalent radical hydroxyl (MO) (peroxide ot" hydrogen, IPO.) 

IPS becoming III IS or UlIs (hydrosulphylide of hydrogen), and 
11 2 becoming H110 or Hllo (hydroxylide of hydrogen). 



302 SALTS OF ACIDULOUS RADICALS. 

Synthetical Reactions. 
Sulphuretted Hydrogen. 

First Synthetical Reaction : The preparation of sulphuretted 
hydrogen. — This operation was described on page 95, and prob- 
ably has already been studied by the reader. 

Precipitated Sulphur. 

Second Synthetical Reaction. — Prepare the variety of the 
radical of sulphides known as Precipitated Sulphur (Sulphur 
Prsccipitatum, U. S. P.), or milk of sulphur, by boiling a few 
grains of flowers of sulphur (100 parts) with slaked lime (66 
parts) and some water (500 parts) in a test-tube (larger 
quantities in an evaporating-basin), filtering, and (reserving a 
small portion of the filtrate) adding diluted hydrochloric acid 
until the well-stirred milklike liquid has still a faint alkaline or 
scarcely acid reaction on test-paper ; sulphur is precipitated, and 
may be collected on a filter, washed and dried (at about 120°). 
Excess of acid must be avoided, or some hydrosulphyl, the 
liquid persulphide of hydrogen (H 2 S 2 ), will be formed, probably 
causing the particles of sulphur to aggregate to a gummy mass. 

This is the process of the Pharmacopoeias. Porysulphide of cal- 
cium and hyposulphite of calcium are formed : — 



5CaH 2 2 


+ 6S 2 : 


= 2CaS 6 -f 


- CaS 2 3 + 


3H 2 


Hydrate of 


Sulphur. 


Polysulphide 


Hyposulphite 


Water. 


calcium. 




of calcium. 


of calcium. 





On adding the acid, both salts are decomposed and, after an inter- 
mediate reaction, sulphur separates : — 

2CaS 5 + CaS 2 ? + 6HC1 = 3CaCl 2 + 3H 2 + 6S 2 

Polysulphide Hyposulphite Hydrochloric Chloride of Water. Sulphur, 

of calcium. of calcium. acid. calcium. 

The polysulphide of calcium yields sulphuretted hydrogen and 
milk-white sulphur on the addition of acid. The hyposulphite of 
calcium then yields sulphurous acid gas as well as a yellowish sul- 
phur. The gases react and give sulphur and water, very little sul- 
phuretted hydrogen escaping : this is the intermediate reaction just 
alluded to. A little pentathionic acid (see Index) is also said to be 
formed. 

4H 2 S + 2S0 2 = 3S 2 + 4H 2 0. 

Calcareous Precipitated Sulphur : The old " Milk of Sul- 
phur." — To a sulphur solution prepared as before (or to the 
reserved portion) add a little dilute sulphuric acid ; the pre- 
cipitate is in this case largely mixed with sulphate of cal- 



sulphites. 303 

2CaS 5 + CaS 2 0, + 3H 2 S0 4 + 3H 2 = 3(CaS0 4 ,2H 2 0) 

Polysulphide Hyposulphite Sulphuric Water. Sulphate of 

of calcium. of calcium. acid. calcium. 

+ 6S 2 

Sulphur. 

Place a little of each of these specimens of precipitated sul- 
phur with a drop of the supernatant liquid on a strip of glass, 
cover each spot with a piece of thin glass, and examine the 
precipitates under a microscope ; the pure sulphur will be found 
to consist of minute grains or globules, the calcareous to con- 
tain comparatively large crystals (sulphate of calcium), 

Note. — A large proportion of the precipitated sulphur met with 
in trade in England still is thus mixed with sulphate of calcium, 
most of such specimens containing two-thirds of their weight of 
that substance. Many purchasers, indeed, are so accustomed to the 
satiny appearance of the mixed article as to regard the real sulphur 
with suspicion, sometimes refusing to purchase it. The mixed arti- 
cle is, certainly, more easily mixable with aqueous liquids ; 

Many English pharmacists have ceased to sell any sulphur which 
yields a white ash (the anhydrous sulphate) when a little is burnt 
off on the end of a table-knife or spatula. (No more damage is 
done to the steel than a rub on a knife-board will remove.) 

To ascertain exactly the amount of sulphate of calcium in a speci- 
men of calcareous precipitated sulphur, place a weighed quantity in 
a tared crucible and heat till no more vapors are evolved. The 
weight of the residual anhydrous sulphate of calcium (CaS0 4 = 136)$ 
with one-fourth thereof added, is the amount of crystalline sulphate 
of calcium (CaS0 4 ,2H 2 = 172) present in the original quantity of 
calcareous sulphur. 

Analytical Reactions ( Tents). 

To a sulphide add a few drops of hydrochloric acid ; sul- 
phuretted hydrogen will probably be evolved, well known by 
its smell. If the sulphide is not acted upon by the acid, or if 
free sulphur be under examination, mix a minute portion with 
a fragment of solid caustic potash or soda and fuse on a silver 
coin or old spoon. When cold, place a drop of dilute hydro- 
chloric acid on the spot ; sulphuretted hydrogen is evolved, and 
a black stain, due to sulphide of silver (Ag 2 S) left on the coin. 

Other sulphur reactions may be adopted as tests, but the above 
are sufficient for all ordinary purposes. The most convenient re- 
agent for detecting a sulphide in solution of ammonia is ammonio- 
sulphate of copper, which gives a black precipitate of sulphide oi' 
copper if a sulphide be present. 

The Iodide oj Sulphur (S 2 I 2 ) has been mentioned under " Iodine." 



304 SALTS OF ACIDULOUS RADICALS. 

A chloride (S 2 C1 2 ) and bromide (S 2 Br 2 ) may also be formed from 
their elements. A mixture of sulphur and chloride of sulphur is 
sometimes met with under the name of Jujpochloride of sulphur. 



QUESTIONS AND EXERCISES. 

495. In what form does sulphur occur in nature ? 

496. State the modes of preparation of the three chief commercial 
varieties of sulphur. 

497. To what extent does the atom of sulphur vary in quanti va- 
lence ? 

498. State the relations of acid salts to acids and to normal salts. 

499. Define sulphides and sulphydrates. 

500. Describe the preparation of sulphuretted hydrogen. 

501. What are the characters of pure precipitated sulphur? 

502. Give equations explanatory of the reactions which occur in 
precipitating sulphur according to the official process. 

503. Describe the microscopic test for calcareous precipitated 
sulphur. 

504. Mention a ready physical method of detecting sulphate of 
calcium in precipitated sulphur. 

505. Mention the tests for sulphides, and the character by which 
sulphuretted hydrogen is distinguished from other sulphides. 

506. How are sulphides insoluble in acids tested for sulphur ? 

507. Give a method for the detection of a trace of sulphur in solu- 
tion of ammonia. 



SULPHUROUS ACID AND OTHER SULPHITES. 

Formula of Sulphurous Acid H 2 S0 3 . Formula of sulphurous acid gas 
or sulphurous anhydride, sometimes termed sulphurous acid, S0 2 . 
Molecular weight of sulphurous acid 82 ; of the anhydride 64. 

"When sulphur is burned in the air it combines with oxygen and 
forms sulphurous acid gas (S0 2 ), more correctly termed sulphurous 
anhydride, or occasionally, but erroneously, sulphurous acid. It is a 
pungent, colorless gas, readily liquefied on being passed through a 
tube externally cooled by a freezing-mixture composed of two parts 
of well-powdered ice (or, better, snow) with one part of common 
salt. If sulphurous acid gas becomes moist or is passed into water, 
heat is evolved and true sulphurous acid (H 2 S0 3 ) formed. The 
latter body may be obtained in crystals by freezing a strong aqueous 
solution ; but it is very unstable, and hence the properties of the 
sulphurous radical must be studied under the form of some other 
sulphite ; sulphite of calcium (CaS0 3 ) or sulphite of sodium (Na 2 S0 3 ) 
may be used for the purpose. 

Quantivalence. — The radical of the sulphites is bivalent (S0 3 7/ ), 
and hence forms acid sulphites, such as acid sulphite of potassium 
(KHS0 3 ), and normal sulphites, such as sulphite of sodium (Na 2 S0 3 ). 

Note on Nomenclature. — The sulphites are so named from the 
usual rule, that salts corresponding with acids whose names end in 



SULPHITES. 305 

ons have a name ending in ite. They are generally made by pass- 
ing sulphurous acid gas over moist oxides or carbonates ; in the 
latter case carbonic acid gas escapes. 

Synthetical Reaction. — To a few drops of sulphuric acid in a 
test-tube add a piece of charcoal and apply heat ; sulphurous 
acid gas is evolved, and may be conveyed by a bent tube into 
a small quantity of cold water in another test-tube. Larger 
quantities may be made in a Florence flask. The product is 
the Acidum Sulphurosum, U. S. P. It contains about 4.5 per 
cent, of sulphurous acid (H 2 S0 3 ) or about 3.5 per cent, of the 
gas (S0 2 ). The process is also that described in the Pharma- 
copoeia, except that the gas is purified by passing through a 
small wash-bottle before final collection. Specific gravity 1.022 
to 1.023. 

4H 2 S0 4 -f C 2 = 2C0 2 + 4H 2 + 4S0 2 

Sulphuric Carbon Carbonic Water. Sulphurous 

acid. (charcoal). acid gas. acid gas. 

Sulphurous acid gas may also be made by boiling copper, 
mercury, or iron with sulphuric acid, sulphate of the metals 
being formed. Also by boiling sulphur with sulphuric acid. 
The gas passed into water yields sulphurous acid. 

S0 2 + H 2 = H 2 S0 3 

Sulphurous acid gas. W T ater. Sulphurous acid. 

If in this process the water were replaced by solutions of or solid 
metallic oxides or carbonates, sulphites of the various metals would 
be formed. The formula of sulphite of potassium (Potassii Sulphis, 
U. S. P.) is K ? S0 3 ,2H 2 ; of sulphite of sodium (Sodii Sulphis, 
U. S. P.), Na 2 80 3 ,7H 2 ; of the bisulphite or acid sulphite, NalIS0 3 
(Sodii Bisulphis, U. S. P.). Under the name of antichlor the former 
is used for removing traces of chlorine from paper pulp. The sul- 
phite of magnesium (Magnesii Sulphis, U. S. P., MgS0 3 ,6H 2 0) is 
deposited as a white crystalline powder from the aqueous solution 
containing excess of sulphurous acid. The so-called Bisulphite of 
Lime, employed by brewers for retarding or arresting fermentation 
and oxidation, and employed for various antiseptic purposes, is a 
solution of sulphite of calcium (CaS0 3 ) in free sulphurous acid 
(II 2 S0 3 ), and is made by passing sulphurous acid gas (80 2 ) into thin 
milk of lime. Its specific gravity varies from 1.050 to 1.070. and its 
potential strength of anhydride (S0 2 ) from 4 to G per cent. Sul- 
phurous acid is very soluble in alcohol. 

Analytical Reactions (Tests). 
First Analytical Reaction. — To a sulphite (of sodium, lor 
instance, made by passing sulphurous acid gas into solution of 
carbonate of sodium) add a drop or two of diluted hydrochloric 
acid; sulphurous acid gas escapes, recognized by a peculiar 
pungent smell. 



306 SALTS OF ACIDULOUS RADICALS. 

This smell is the same as that evolved on burning lucifer matches 
that have been tipped with sulphur. It is due, probably, not to the 
gas (S0 2 ), but to sulphurous acid (II 2 S0 3 ), formed by the union of 
sulphurous acid gas with either the moisture of the air or that on 
the surface of the mucous membrane of the nose. The gas is highly 
suffocating. 

Second Analytical Reaction. — To a sulphite add a little 
water, a fragment or two of zinc, and then hydrochloric acid ; 
sulphuretted hydrogen will be evolved, known by its odor 
and by its action on a piece of paper placed like a cap on the 
mouth of the test-tube, and moistened with a drop of solution 
of acetate of lead, black sulphide of lead being formed. Sul- 
phurous acid may be detected in acetic acid, or in hydrochloric 
acid, by this test. 

H 2 S0 3 + H G - H 2 S + 3H 2 0. 

Other Analytical Reactions. 
To solutions of neutral sulphites add nitrate or chloride of 
barium, chloride of calcium, or nitrate of silver ; in each case 
white sulphites of the various metals are precipitated. The 
barium sulphite is soluble in weak hydrochloric acid ; but if a 
drop or two of chlorine-water is first added, barium sulphate is 
formed, which is insoluble in acids. The other precipitates are 
also soluble in acids. The silver sulphite is decomposed on 
boiling, sulphuric acid being formed, and metallic silver set 
free, the mixture darkening in color. 

To recognize the three radicals in an aqueous solution of sul- 
phides, sulphites, and sulphates, add chloride of barium, filter, and 
wash the precipitate. In the filtrate, sulphides are detected by the 
sulphuretted hydrogen evolved on adding an acid. In the pre- 
cipitate, sulphites are detected by the odor of sulphurous acid pro- 
duced on adding hydrochloric acid, and sulphates by their insolu- 
bility in the acid. 



QUESTIONS AND EXERCISES, 

508. What are the differences between sulphurous acid and sul- 
phurous acid gas, sulphites and acid sulphites? 

509. State the characters of sulphurous acid gas? 

510. How is the official Sulphurous Acid prepared? 

511. By what test may sulphurous acid be recognized in acetic 
acid ? 

512. Give a method by which sulphites may be detected in pres- 
ence of sulphides and sulphates. 



SULPHATES. 307 

SULPHURIC ACID AND OTHER SULPHATES. 

Formula of Sulphuric Acid, H 2 S0 4 . Molecular weight, 98. 

Many sulphates occur in nature 5 but the common and highly im- 
portant hydrogen sulphate, sulphuric acid, is made artificially. 

Preparation of the Acid : General Nature of the Process. — Sulphur 
itself, or sometimes the sulphur in iron pyrites, is first converted into 
sulphurous acid gas by burning in air, and this gas, by moisture and 
oxygen, into sulphuric acid (S0 2 -f H 2 -\- = H 2 S0 4 ). 

Details of the Process. — The oxygen necessary to oxidize the sul- 
phurous acid gas cannot directly be obtained from air, but indirectly, 
the agency of nitric oxide (NO) being employed — this gas becoming 
nitric peroxide (N0 2 ) by the action of the air, and the nitric peroxide 
again becoming nitric oxide by the action of the sulphurous acid gas, 
and so on. A small quantity of nitric oxide gas will thus act as 
carrier of oxygen from the air to very large quantities of sulphurous 
acid. Nitrous anhydride (N 2 3 ) may also act as the carrier. 

The following equations represent the chief successive steps : — 



S 2 + 20 2 

Sulphur. Oxygen 
(of the air) 

S0 2 4- H 2 

Sulphurous Water, 
acid gas. 


= 2S0 2 

Sulphurous, 
acid gas. 

= H 2 S0 3 

Sulphurous 
acid. 


2NO + 2 

Nitric Oxygen 
oxide. (of the air) 


= 2N0 2 

Nitric 
peroxide. 


H 2 S0 3 + N0 2 = 

Sulphurous Nitric 
acid. peroxide. 


II 2 S0 4 + NO 

Sulphuric Nitric 
acid. oxide. 



On the large scale the sulphurous acid gas is produced by burning 
sulphur in furnaces ; it is carried, together with the nitric vapors, 
by flues into leaden chambers, where jets of steam supply the neces- 
sary moisture ; the steam also, condensing, prevents other reactions. 

The resulting dilute sulphuric acid is concentrated by evaporation 
in leaden vessels. 

The nitric oxide is in the first instance obtained from nitric acid, 
and this from nitrate of potassium or of sodium by the action of a 
small quantity of the sulphuric acid of a previous operation. 

2NaN0 3 + H 2 SO, = Na,SO, + 2TTN0 3 

Nitrate of Sulphuric Sulphate of Nitric 

sodium. acid. sodium. acid. 

3H 2 S0 3 + 2HN0 8 = 3H,S0 4 + TT.,0 + 2NO 

Sulphurous Nitric Sulphuric Water. Nitric 

acid. acid. acid. oxide. 

Other Processes. — Sulphuric acid may be obtained by other pro- 
cesses, as by distilling the sulphate of iron resulting from the natural 
oxidation of iron pyrites by air; but it is seldom so made at the 



308 



SALTS OF ACIDULOUS RADICALS. 



present day. The sulphate of iron was formerly called green vitriol 
(p. 142), and the distilled product oil of vitriol ; the latter in allu- 
sion to its consistence and origin. 

Experiment. — For purposes of practical study, a small quantity 
may be made (as shown in fig. 39) by passing, a/sulphurous acid gas 
(p. 304), b, nitric oxide in small quantity (p. 288), c, air (forced 
through by aid of bellows or a gas-holder or drawn through by 




Experimental Manufacture of Sulphuric Acid. 

a icater-asjiirator, e), and occasionally, c?, steam (generated in a 
Florence flask) through glass tubes, nearly to the bottom of a two- 
or three-quart flask. 

S0 2 + H 2 = H 2 S0 3 ; | 2NO + 2 ■= 2N0 2 : 
H 2 S0 3 + X0 2 = H 2 S0 4 + NO. 

A slow current of sulphurous acid gas, air, and steam, and a small 
quantity of nitric oxide, will furnish, in the course of a few minutes, 
enough sulphuric acid for recognition by the first of the following 
analytical reactions. The manufacturing process may be more ex- 
actly imitated by burning sulphur in a tube placed where the flask a 
is represented in the foregoing figure, or by burning it under a 
funnel there attached ; but in either of these cases strong aspiration 
must be maintained. 

Purification. — Sulphuric acid may contain arsenic, nitrous com- 
pounds, and salts (sulphate of lead, etc.). Arsenic may be detected 
by the hydrogen test (p. 171) or the stannous chloride test (p. 173), 



SULPHATES. 309 

nitrous compounds by powdered sulphate of iron (which acquires a 
violet tint if they are present), and salts by the residue left on boil- 
ing a little to dryness in a crucible in a fume-chamber. If only 
nitrous compounds are present, the acid may be purified by heating 
with about one-half per cent, of sulphate of ammonium — water 
and nitrogen being produced (Pelouze). If arsenic occurs, boil 
with a small quantity of hydrochloric acid, which converts the arsenic 
into chloride of arsenicum ; or heat with a little nitric acid, which 
converts arsenious (As 2 3 ) into arsenic anhydride (As 2 5 ), then add 
sulphate of ammonium, and distil in a retort containing pieces of 
quartz and heat by an annular-shaped burner (to prevent " bump- 
ing ;" see p. 279). The arsenic anhydride remains in the retort. 
(Arsenious anhydride would be carried over with the sulphuric acid 
vapors.) By distillation the acid is also purified from salts (such as 
NaHS0 4 ) which are not volatile. 

Quantivalence. — The sulphuric radical being bivalent (SO/ 7 ), acid 
as well as normal sulphates may exist. Acid sulphate of potassium 
(KHS0 4 ) is an illustration of the former, sulphate of sodium (Na 2 S0 4 ) 
of the latter ; double sulphates may also occur, such as that of potas- 
sium and magnesium (K 2 S0 4 ,MgS0 4 ,6H 2 0). Sulphates generally 
contain water of crystallization. 

Pure sulphuric acid (H 2 S0 4 ) is of specific gravity 1.848. The 
best "oil of vitriol" of commerce, a colorless liquid of oily consist- 
ence, is of specific gravity 1.843, and contains about 98 per cent, of 
real acid (H 2 S0 4 ). A variety less pure than this "white" acid is 
known as " brown acid." The Acidum Sulphuricum, TJ. S. P., should 
contain not less than 96 per cent, of H 2 S0 4 , and have a sp. gr. not 
below 1.840. The Acidum Sulphuricum Dilutum, U. S. P., contains 
10 per cent, of the strong acid, and should have a sp. gr. of nearly 
1.057. The Acidum Sulphuricum Aromaticum, U. S. P., a dilute 
acid in which are dissolved oil of cinnamon and tincture of ginger, 
contains about 20 per cent, of strong acid, sp. gr. 0.955. There are 
some definite compounds of sulphuric acid with water 5 the first 
(H 2 S0 4 ,H 2 0) may be obtained in crystals. 

Sulphuric anhydride (S0 3 ) is a white silky crystalline solid having 
no acid properties. It is made by distilling sulphuric acid with 
phosphoric anhydride (H 2 S0 4 + P 2 5 = 2HP0 3 + S0 3 ). On the 
large scale, sulphuric acid is dissociated by heat, and the dried sul- 
phurous anhydride and oxygen made to reeombine. It appears to 
unite with sulphuric acid and some other normal sulphates to form 
compounds (R/ 2 S0 4 ,S0 3 ) resembling in constitution red chromate of 
potassium or borax. The fuming sulphuric acid (II 2 S0 4 ,S0 3 ), for- 
merly made at Nordhausen in Saxony, seems to be such a body. 

Note. — Sulphuric acid is a most valuable compound to all chemists 
and manufacturers of chemical substances. By its agency, direct or 
indirect, many, if not most, chemical transformations arc effected. 
To describe all its uses would be to write a work on chemistry. 

Analytical I unci ions. (jPeste). 
First Analytical Reaction. — To a solution oi' a sulphate add 



310 SALTS OF ACIDULOUS RADICALS. 

solution of a barium salt ; a white precipitate of sulphate of 
barium (BaS0 4 ) falls. Add nitric acid and boil the mixture ; 
the precipitate does not dissolve. 

This reaction is as highly characteristic of sulphate as it has been 
stated to be of barium salts (vide page 103). The only error likely 
to be made in its application is that of overlooking the fact that 
nitrate and chloride of barium are less soluble in strong acid than in 
water. On adding the barium salt to the acid liquid, therefore, a 
white precipitate may be obtained, which is simply the nitrate or 
chloride of barium. The appearance of such a precipitate diifers con- 
siderably from that of the barium sulphate, hence a careful operator 
will not be misled. Should any doubt remain, water should be added, 
which will dissolve the nitrate or chloride, but not affect the sulphate. 

Second Analytical Reaction. — Mix a fragment of an insoluble 
sulphate (BaS0 4 , e. g.~) with carbonate of potassium or of sodium ; 
or, better, with both carbonates, and fuse the mixture in a small 
crucible. Digest the residue when cold, in water, and filter ; 
the filtrate may be tested for the sulphuric radical. 

This is a convenient method of qualitatively analyzing insoluble 
sulphates, such as those of barium and lead. 

Third Analytical Reaction. — Mix a fragment of an insoluble 
sulphate with a little alkaline carbonate on a piece of charcoal, 
taking care that some of the charcoal-dust is included in the 
mixture. Heat the little heap in the blowpipe-flame until it 
fuses, and, when cold, add a drop of acid ; sulphuretted hydro- 
gen is evolved, recognized by its odor. 

This is another process for the recognition of insoluble sulphates. 
Other preparations of sulphur, and sulphur itself, give a similar re- 
sult. It is therefore rather a test for sulphur and its compounds than 
sulphates only ; but the absence of other salts can generally, if neces- 
sary, be previously determined. 

Note. — The presence of the sulphuric radical in a solution having 
been proved by the above reactions, its occurrence as the normal sul- 
phate of a metal is demonstrated by the neutral, or nearly neutral, 
deportment of the liquid with test-paper, and the detection of the 
metal — its occurrence as sulphuric acid or an acid sulphate by the 
sourness of the liquid to the taste and the effervescence produced on 
the addition of a carbonate. 

Antidote. — In cases of poisoning by strong sulphuric acid, solution 
of carbonate of sodium (common washing-soda), magnesia and water, 
etc., may be administered as antidotes. 



QUESTIONS AND EXERCISES. 

513. What is the formula of sulphuric acid, and what its molecular 
weight? 



CARBONATES. 311 

514. How is it related to other sulphates? 

515. Write a short article on the manufacture of sulphuric acid, 
giving either diagrams or equations. 

516. How may nitrous compounds be detected in, and eliminated 
from, sulphuric acid? 

517. State the method by which the presence of arsenic is detected 
in sulphuric acid, and explain the process by which it may be re- 
moved. 

518. Define sulphates, acid sulphates, and double sulphates. 

519. What percentage of real acid is contained in commercial oil 
or vitriol ? 

520. State the strength of the official "diluted" and "aromatic" 
sulphuric acid. 

521. By what process is sulphuric anhydride obtained from Nord- 
hausen sulphuric acid ? 

522. Explain the reactions which occur in testing for sulphates. 

523. Ascertain by calculation the weight of oil of vitriol (of 96.8 
per cent.) necessary for the production of one ton of dry sulphate 
of ammonium. — Ans. 1718 pounds. 

524. Name the antidotes in cases of poisoning by strong sulphuric 
acid. 



CARBONIC ACID AND OTHER CARBONATES. 

Formula of Carbonic Acid, H 2 C0 3 ; molecular weight, 62. Formula 
of carbonic acid gas, or carbonic anhydride, commonly termed car- 
bonic acid, C0 2 ; molecular weight, 44. 

Sources. — Carbonates (compounds containing the grouping C0 3 ) 
•are very common in nature, the calcium carbonate (CaC0 3 ) being 
widely distributed as chalk, limestone, or marble. The hydrogen 
carbonate, true carbonic acid, is not known, unless indeed carbonic 
acid gas assumes that condition on dissolving in water. Such a so- 
lution (see page 86) changes the color of blue litmus-paper, and the 
gas does not ; this may be because only the true acid (H 2 CO..) affects 
the litmus, or because the gas (C0 2 ) cannot come into real contact 
with the litmus without a medium. From the commonest natural 
carbonate, carbonate of calcium, are derived the carbonic constit- 
uents of the one most frequently used in medicine and in the arts 
generally, carbonate of sodium. 

Carbonate of sodium is prepared, by "the Lcblanc process," from 
the chief natural salt, the chloride. After the chloride 1 has been 
converted into sulphate (salt-cake) by sulphuric acid (or by sulphur- 
ous acid, air, and steam — Ilargreave's modification) — 

2NaCl + H 2 SO, = Na 2 S0 4 + 2HCI, 

the sulphate is roasted with limestone and small coal, by which car- 
bonate of sodium and sulphide of calcium arc formed : — 

Na.^SO, + C 4 + CaC0 3 = CaS + Na,C0 3 -\ 4CO. 

Carbonic oxide gas and a little carbonic acid gas from the excess of 



312 SALTS OF ACIDULOUS RADICALS. 

chalk escape ; the residual mass (black ash) is digested, in water, in 
which the carbonate of sodium dissolves, the sulphide of calcium with 
a little oxide remaining insoluble. The solution is evaporated to 
dryness, and yields true carbonate of sodium. This is roasted Avith 
a small quantity of sawdust, to convert any caustic soda resulting 
from the action of the lime on the carbonate into normal carbonate. 
The product is soda-ash. Dissolved in water and crystallized, it 
constitute the ordinary " soda" used for washing purposes 5 recrys- 
tallized and sometimes ground, it forms the official carbonate of 
sodium (Sodii Carbonas, U. S. P.) (Na 2 CO 3 ,10H 2 O). The reaction 
is rendered more intelligible by regarding it as occurring in two 
stages : 1st, the reduction of the sulphate of sodium to sulphide by 
the carbon of the coal — 

Na,S0 4 + C 4 = Na 2 S + 4CO ; 

2d, the reaction of the sulphide of sodium and carbonate of calcium, 
giving soluble carbonate of sodium, thus — 

Na 2 S + CaC0 3 = Na 2 C0 3 + CaS. 

The sulphur in the residual sulphide (or, perhaps, oxysulphide) of 
calcium may be recovered by exposure to the waste carbonic acid gas 
of lime-kilns, carbonate of calcium being formed and the diluting 
nitrogen passing off, more carbonic acid afterward causing sulphur- 
etted hydrogen to be set free. The latter is either burnt and con- 
verted into sulphuric acid, or is caused to react with air on ferric 
oxide, sulphur being set free. 

Another Process. — To a strong solution of common salt bicar- 
bonate of ammonium is added, when a precipitate of bicarbonate of 
sodium (Sodii Bicarbonas, B. P.) occurs. The resulting chloride of 
ammonium may be converted into carbonate by heating with chalk, 
and the carbonate be more fully carbonated by carbonic acid gas 
obtained by heating the bicarbonate of sodium, which is thereby 
reduced to the ordinary neutral carbonate (Sodii Carbonas , B. P.). 
This method is known as "the ammonia process." 

Carbonic acid gas (C0 2 ) is a product of the combustion of all car- 
bonaceous matters. It is constantly exhaled by animals and inhaled 
by plants, its intermediate storehouse being the atmosphere, through- 
out which it is equally distributed by diffusion (vide p. 24) to the 
extent of about 4 parts in 10,000. A larger proportion than that 
just mentioned gives to confined air depressing effects, 4 or 5 per 
cent, rendering the atmosphere poisonous when taken into the blood 
from the lungs. Carbonic acid, however, may be taken into the 
stomach with beneficial sedative effects ; hence, probably, much of 
the value of such effervescing liquids as soda-water, lemonade, and 
solutions of the various granulated preparations and effervescing 
powders (vide p. 87). The gas liquefies on being compressed, and 
the liquid solidifies on being cooled. Carbonic acid gas is twenty- 
two times as heavy as hydrogen, and about half as heavy again as 
air. At common temperatures it dissolves in about its own volume 
of water, both being under the same pressure, the water retaining 
gas strongly if all air has previously been expelled. 



CARBONATES. 313 

Sidphocarbonates resemble carbonates in constitution, but contain 
sulphur in place of oxygen. 

Sulphocarbonic anhydride, CS 2 , commonly termed bisulphide of 
carbon or disulphide of carbon (Carbonei Bisulphidum, U. S. P.), is 
a highly volatile and inflammable liquid, easily made from its ele- 
ments. Sp. gr. 1.272; boiling-point 46° C. It may be rendered 
almost scentless by digestion with lime and then with copper turn- 
ings. Its possible impurities are dissolved sulphur, sulphur oils, 
and sulphuretted hydrogen. 

Keactions. 
Synthetical and Analytical Reactions, — 1. To a fragment of 
marble in a test-tube add water and then hydrochloric acid ; 
carbonic acid gas (C0 2 ) is evolved, and may be conveyed into 
water or solutions of salts by the usual delivery-tube. 

This is the process of the British Pharmacopoeia, and the one 
usually adopted for experimental purposes. On the large scale the 
gas is prepared from chalk or marble and sulphuric acid, frequent 
stirring promoting its escape. 

2. Pass the gas into lime-water ; a white precipitate of car- 
bonate of calcium (CaC0 3 ) falls. Solution of subacetate of 
lead may be used instead of, and is perhaps even a more deli- 
cate test than, lime-water. 

The evolution of a gas on adding an acid to a salt, warming the 
mixture if necessary, the gas being inodorous and giving a white 
precipitate with lime-water, is sufficient evidence of the presence of 
a carbonate. Carbonates in solution of ammonia, potash, or soda 
may be detected by the direct addition of solution of lime. Car- 
bonates in presence of sulphites or hyposulphites may be detected 
by adding acid tartrate of potassium, which decomposes carbonates 
with effervescence, but does not attack sulphites or hyposulphites. 

3. Blow air from the lungs through a glass tube into lime- 
water ; the presence of carbonic acid gas is at once indicated. 

The passage of a considerable quantity of normal air through lime- 
water produces a similar effect. A bottle containing lime-water soon 
becomes coated with carbonate of calcium from absorption of atmo- 
spheric carbonic acid gas. 

4. Fill a dry test-tube with the gas by pressing the delivery- 
tube of the above apparatus to the bottom of the test-tube. 
Being rather more than once and a half as heavy as the air 
(1.529), it will displace the latter. Prove the presence of the 
gas by pouring it slowly, as if a visible liquid, into another 
test-tube containing lime-water ; the characteristic cloudiness 
and precipitate are obtained on gently shaking the lime-water. 

In testing for carbonates by bringing evolved gas into contact with 
lime-water, the preparation and adaptation of a delivery-tube may 

27 



314 SALTS OF ACIDULOUS RADICALS. 

often be avoided by pouring the gas from the generating-tube into 
that containing the lime-water in the manner just indicated. 

5. Pass carbonic acid gas through lime-water until the pre- 
cipitate at first formed is dissolved. The resulting liquid is a 
solution of carbonate of calcium in carbonic acid water. Boil 
the solution ; carbonic acid gas escapes, and the carbonate is 
again precipitated. 

This experiment will serve to show how chalk is kept in solution 
in ordinary well-waters, giving the property of " hardness," and how 
the fur or stone-like deposit in tea-kettles and boilers is formed. It 
should be here stated that sulphate of calcium produces similar 
hardness, and that these, with small quantities of the sulphate and 
carbonate of magnesium, constitute the hardening constituents of 
well-waters, a curd (oleate of calcium or magnesium) being formed 
whenever soap is used with such waters. An enormous amount of 
soap is wasted through the employment of hard water for washing 
purposes. The hardness produced by the earthy carbonates is 
termed "temporary hardness," because removable by ebullition; 
that by the earthy sulphates "permanent hardness," because un- 
affected by ebullition. The addition of lime-water or a mixture of 
lime and water removes temporary hardness (reac. 2, page 313) 
and carbonate of sodium, " washing soda," both temporary and 
permanent hardness, in the latter case sulphate of sodium remain- 
ing in solution. Carbonate of barium (ground witherite) also de- 
composes sulphates of calcium and magnesium, sulphate of barium 
being precipitated and carbonates of calcium or magnesium formed ; 
the latter and the carbonates originally in the water may then be 
precipitated by ebullition or by the action of lime-water. But the 
injurious effects of barium salts on man and the lower animals 
prevent the carbonate being used for purifying water for drink- 
ing purposes, as by accident or an unforeseen reaction a portion 
might become dissolved. 

6. Add a solution of carbonate of potassium or sodium to a 
mercuric salt ; a brownish-red precipitate results. Add a solu- 
tion of bicarbonate of potassium or sodium to a mercuric solu- 
tion ; a white precipitate results, becoming red after some 
time. 

QUESTIONS AND EXERCISES. 

525. Name the chief natural carbonates. 

526. What are the formulae of carbonic acid and carbonic acid 
gas? 

527. Adduce evidence of the existence of true carbonic acid. 

528. Trace the steps by Avhich the carbonic constituent of chalk 
is transferred to sodium by the process usually adopted in alkali- 
works — the manufacture of " soda." 

529. Carbonic acid gas is constantly exhaled from the lungs of 
animals ; why does it not accumulate in the atmosphere? 



OXALATES. 315 

5S0. What is the effect of pressure on carbonic acid gas ? 

531. State the specific gravity of carbonic acid gas. 

532. By what processes may carbonic acid gas be obtained for 
experimental and manufacturing purposes? 

533. Describe the action of carbonic acid gas on the carbonates 
of potassium or sodium. 

534. How may carbonic acid be detected in expired air ? 

535. To what extent is carbonic acid gas heavier than air? 

536. Work sums showing what quantity of chalk (90 per cent, 
pure) will be required to furnish the carbonic acid necessary to 
convert one ton of carbonate of potassium (containing 83 per cent, 
of K 2 C0 3 ) into acid carbonate, supposing no gas to be wasted ? — 
Ans. 1500 lbs. 

537. Define "hardness" in water. 

538. How may the presence of carbonates be demonstrated? 



OXALIC ACID AND OTHER OXALATES. 

Formula of Oxalic Acid H 2 C 2 4 ,2H 2 0. Molecular weight 126. 

Source. — Oxalates occur in nature in the juices of some plants, as 
wood-sorrel, rhubarb, the common dock, and certain lichens ; but 
the hydrogen oxalate (oxalic acid) and other oxalates are all made 
artificially. The carbon of many organic substances yields oxalic 
acid when those substances are boiled with nitric acid, and an alka- 
line oxalate when they are roasted with a mixture of the hydrates 
of potassium and sodium. 

Experimental Process. — On the small scale, a mixture of nitric 
acid 10 parts, loaf sugar 2 parts, and water 3 parts, quickly yields 
the acid. Abundance of red fumes are at first evolved. On cool- 
ing, crystals are deposited. A more dilute acid, kept warm, acts 
more slowly, but yields a larger product. 

Manufacturing Process. — On the large scale, sawdust is roasted 
with alkalies, resulting oxalate of sodium decomposed by lime with 
formation of oxalate of calcium, the latter digested with sulphuric 
acid, and the liberated oxalic acid (Oxalic Acid of Commerce, B. P.) 
made commercially pure by recrystallization. 

Purified Oxalic Acid. — The acid made from sugar, recrystallizcd 
two or three times, is quite pure. Commercial acid should be mixed 
with insufficient water for complete solution, and the mixture occa- 
sionally shaken. Most of the impurities remain undissolved, and the 
saturated solution evaporated yields crystals which are fairly pure. 

Quanticalence. — The elements represented by the formula C.,0 ( are 
those characteristic of oxalates. They form a bivalent grouping; 
hence normal oxalates (R'jjCaO*) and acid oxalates (R'HC a OJ exist. 

Salt of sorrel is a crystalline compound of oxalic acid with acid 
potassium oxalate, the crystals containing two molecules of water 
of crystallization (K 1LC.,(),,M,( , ,0,.L > 1I,0); 

Oxalate of iron (Ferri Oxalas, U. S. 1*., FeC.,0,.11,0) is a crvs- 



316 SALTS OF ACIDULOUS RADICALS. 

talline yellow powder. It may be made by precipitating a solution 
of sulphate of iron with an oxalate. When heated in contact with 
air it decomposes with a faint combustion, and leaves a residue of 
not less than 49.3 per cent, of red oxide of iron. 

Analytical Reactions {Tests'). 

First Analytical Reaction . — To solution of an oxalate (oxa- 
late of ammonium, e. g.) add solution of chloride of calcium ; 
a white precipitate falls. Add to the precipitate excess of 
acetic acid ; it is insoluble. Add hydrochloric acid ; the pre- 
cipitate is dissolved. 

The formation of a white precipitate on adding a calcium or ba- 
rium salt, insoluble in acetic but soluble in hydrochloric or nitric 
acid, is usually sufficient proof of the presence of an oxalate. The 
action of the liquid on litmus-paper, effervescence with carbonate 
of sodium, and absence of metals, would indicate that the oxalate is 
that of hydrogen, oxalic acid. 

Note — The barium oxalate is slightly soluble in acetic acid 
(Souchay and Lenssen), and enough may be dissolved by this acid 
from a mixed barium precipitate (produced on adding chloride or 
nitrate of barium to a solution of mixed salts) to give the foregoing 
reaction on adding chloride of calcium to the filtered acetic liquid — 
an effect sometimes useful in the analysis of mixed substances 
(Davies). 

Antidote. — In cases of poisoning by oxalic acid or salt of sorrel, 
chalk and water may be administered as a chemical antidote (with 
the view of producing the insoluble oxalate of calcium), emetics and 
the stomach-pump being used as soon as possible. 

Second Analytical Reaction. — Heat a fragment of any dry 
common fixed metallic oxalate (an oxalate of potassium, for 
example) in a test-tube ; decomposition occurs, carbonic oxide 
(CO) (a gas that will be noticed subsequently) is liberated, 
and a carbonate of the metal remains. Add water and then 
an acid to the residue ; effervescence occurs. 

This is a ready test for ordinary insoluble oxalates, and is trust- 
worthy if,' on heating the substance, no charring occurs, or not more 
than gives a gray color to the residue. Organic salts of metals de- 
compose when heated, and leave a residue of carbonate, but except 
in the case of oxalate the residue is always accompanied by much . 
charcoal. Insoluble oxalates and organic salts of such metals as 
lead and silver are, of course, liable to be reduced to oxide or even 
metal by heat. Such oxalates may be decomposed by boiling with 
solution of carbonate of sodium, filtering, and testing the filtrate for 
oxalates by the chloride-of-calcium test. 

Other Analytical Reactions. — Nitrate of silver gives, with 

oxalates, white oxalate of silver (Ag 2 C 2 4 ). Dry oxalates 

are decomposed when heated with strong sulphuric acid, car- 



TARTRATES. 31 7 

bonic oxide and carbonic acid gas escaping. If much of the 
substance be operated on, the gas may be washed with an al- 
kali, the carbonic acid be thus removed, and the carbonic oxide 
be ignited ; it will be found to burn with a characteristic bluish 

flame. Oxalates, when mixed with water, black oxide of 

manganese (free from carbonates), and sulphuric acid, yield 
carbonic acid gas, which may be tested by lime-water in the 

usual manner. Not only such insoluble oxalates as those of 

lead and silver, above referred, to, but any common insoluble 
oxalates, such as those of calcium and magnesium, may be de- 
composed by ebullition with solution of carbonate of sodium ; 
after filtration the oxalic radical will be found in the clear liquid 
as soluble oxalate of sodium. 



QUESTIONS AND EXERCISES. 

539. Explain the constitution of oxalates. 

540. State how oxalates are obtained. 

541. What is the quantivalence of the oxalic radical? 

542. Give the formula of " salt of sorrel." 

543. Mention the chief test for oxalic acid and other soluble 
oxalates. 

544. Name the antidote for oxalic acid, and describe its action. 

545. By what reactions are insoluble oxalates recognized ? 



TARTARIC ACID AND OTHER TARTRATES. 

Formula of Tartaric Acid Ii^CJI^Og. Molecular weight 150. 

Source. — Tartrates exist in the juice of many fruits ; but it is 
from that of the grape that our supplies are usually obtained. 
Grape-juice contains much acid tartrate of potassium (KHC 4 H 4 6 ), 
which is gradually deposited when the juice is fermented, as in 
making wine-, for acid tartrate of potassium, not very soluble in 
aqueous liquids, is still less so in spirituous, and hence crystallizes 
out as the sugar of the grape-juice is gradually converted into 
alcohol. It is found with tartrate of calcium lining the vessels in 
which wine is kept ; and it is from this crude substance, termed 
arcjal or argol, also from the albumenoid yeasty matter or "lees" 
deposited at the same time, as well as from what tartrate may be 
remaining in the mare left after the juice has been pressed from the 
grapes, that by rough crystallization "tartar," still containing 6 or 
7 per cent, or more of anhydrous tartrate of calcium (CaC 4 H 4 6 ), is 
obtained. From the latter tartaric acid and other tartrates are pre- 
pared. In old dried grapes (Raisins 5 uvce, 1>. P.) crystalline masses 
of tartar and of grape-sugar are constantly met with. 

Cream of Tartar, purified by crystallization (Potassii Ih'tartras, 
27* 



318 SALTS OF ACIDULOUS RADICALS. 

U. S. P.), occurs as a " gritty white powder, or fragments of cakes 
crystallized on one surface ;" of a pleasant acid taste, soluble in 180 
parts of cold and 6 of boiling water, insoluble in spirit* "If 1 
gm. of Bitartrate of Potassium be digested with 5 c.c. of diluted 
acetic acid for half an hour, then diluted with distilled water to 500 
c.c, the solution agitated and filtered, and 25 c.c. of the filtrate 
treated with 5 c.c. of test-solution of oxalate of ammonium, the 
liquid should not become cloudy in less than one minute, nor dis- 
tinctly turbid in less than one minute and a half (absence of more 
than 6 per cent, of tartrate of calcium).'' — U. S. P. 

Quantivalence. — The elements represented by the formula C 4 H 4 6 
are those characteristic of tartrates. They form a bivalent grouping*, 
hence normal tartrates (B/ 2 C 4 H 4 6 ) and acid tartrates (R / HC 4 H 4 6 ) 
exist. Tartrate of potassium, the Potassii Tartras of the U. S. 
Pharmacopoeia (K 2 C 4 II 4 O fi ). and Rochelle Salt, or tartrate of potas- 
sium and sodium (KNaC 4 II 4 6 ,4H 2 0), the official Potassii et Sodii 
Tartras (Soda Tartarata,^. P.), are illustrations of normal tartrates, 
while Cream of Tartar is an example of acid tartrates. The only 
official tartrate not apparently included in these general formulae is 
tartar-emetic (Antimonium Tartaratum, B. P., Antimonii et Potassii 
Tartras, U. S. P.), which is sometimes regarded as the double tar- 
trate of potassium and a hypothetical radical, antimonyl (SbO), thus 
KSbOC 4 H 4 6 . Probably, however, it is but an oxytartrate of anti- 
mony (Sb 2 2 C 4 H 4 6 ) with normal tartrate of potassium (K 2 C 4 H 4 6 ) ; 
for there are several oxycompounds of antimony analogous to the 
ox} 7 compounds of bismuth that have been described (p. 249), normal 
salts partially decomposed by water into oxides, and many of these 
oxycompounds readily unite with normal salts of other basylous 
radicals. Tartar-emetic would thus be oxytartrate of antimony, 
with tartrate of potassium (Sb 2 2 C 4 H 4 6 ,K 2 C 4 H 4 6 ). 

Tartaric Acid. 

Tartaric Acid (Acidum Tart ari cum, U. S. P.) is obtained by boil- 
ing cream of tartar (Potassii Bitartras, U. S. P.) Avith water, adding 
chalk till effervescence ceases, and then chloride of calcium so long 
as a precipitate falls ; the two portions of tartrate of calcium thus 
consecutively formed are thoroughly washed, treated with sulphuric 
acid, the mixture boiled for a short time, resulting sulphate of cal- 
cium mostly separated by filtration, the filtrate concentrated by 
evaporation, any sulphate of calcium that may have deposited re- 
moved as before, and concentration continued until the solution is 

* A boiling solution of tartar yields a floating crust of minute crys- 
tals on cooling— just as milk yields a floating layer of cream, hence the 
term cream of tartar. 

•' It is called tartar," says Paracelsus, "because it produces oil, water, 
tincture, and salt, which burn the patient as Tartarus does." Tartarus is 
Latin (Tapranog, Tartaros, Greek) for hell. The products of its destruc- 
tive distillation are certainly somewhat irritating in taste and smell ; 
and the "salt" (carbonate of potassium) that is left is diuretic, and, 
in larger quantities, powerfully corrosive. 



TARTRATES. 319 

strong enough to crystallize. Tartrate of calcium from 9 ounces 
of cream of tartar requires 5 ounces by weight of sulphuric acid for 
complete decomposition. 

2KIIC 4 H 4 6 + CaC0 3 = CaC 4 H 4 6 + K 2 C 4 H 4 6 + H 2 0+C0 2 

Acid tartrate Carbonate of Tartrate of Tartrate of Water. Carbonic 



of potassium. calcium 


calc: 


ium. 


potassium. 




K 2 C 4 H 4 6 

Tartrate of 
potassium. 


+ 


CaC] 2 

Chloride of 


= 


CaC 4 H 4 6 -f 

Tartrate of 
calcium. 


2KC1 

Chloride of 
potassium. 


2CaC 4 H 4 6 

Tartrate of 
calcium. 


+ 


2H 2 S0 4 

Sulphuric 
acid. 


= 


2CaS0 4 + 

Sulphate of 
calcium. 


2H 2 C 4 II 4 O e 

Tartaric 
acid. 



Tartaric acid occurs in trade in colorless crystals, or the same 
powdered It is strongly acid and readily soluble in water or spirit. 
One part in 8 of water and 2 of spirit of wine forms " Solution of 
Tartaric Acid," B. P. Its aqueous solution is not stable. 

Parcels of tartaric acid often contain crystals of an allotropic or 
physically isomeric modification {vide "Allotropy" and "Isomer- 
ism" in Index). It is termed Paratartaric acid (irapa, para, be- 
side) or Racemic acid (racernus, a bunch of grapes), and is a com- 
bination of ordinary tartaric acid, whose solution twists a ray of 
polarized light to the right hand (dextrotartaric or dextroracemic 
acid), and of leevotartaric or lsevoracemic acid, whose solution twists 
a polarized ray to the left. Racemic acid is inactive in this respect, 
the opposite properties of its constituents neutralizing each other. 
Racemic acid is less soluble in alcohol than tartaric acid. 

Reactions. 
Tartrate of Potassium. 

Synthetical Reaction. — To a small quantity of a strong so- 
lution of carbonate of potassium add acid tartrate of potas- 
sium so long as effervescence occurs ; the resulting liquid is 
solution of normal tartrate of potassium (Potassii Tartras^ 
U. S. P.) (K 2 T), crystals of which may be obtained on evap- 
oration. 

Note. — This is a common method of converting an acid salt of a 
bivalent acidulous radical into a normal salt. The carbonate added 
need not be a carbonate of the same, but may be of a different 
metal ; compounds like Rochelle salt (KNaC 4 H 4 6 ) are then obtained. 
Thus : — 

Tartrate of Potassium and Sodium. 
To a strong hot solution of carbonate of sodium add acid 
tartrate of potassium until effervescence ceases; the resulting 
liquid is solution of tartrate of potassium and sodium ; on cool- 
ing, it yields crystals. This is the official process (Sn,/<, 
Tartarata, B. P.; Potassii et Sodii Tartras, V S, P.) 
(KNaC.lIArUI.O). 



320 



SALTS OF ACIDULOUS RADICALS. 



Na a CO s + 2KHCJIA == 2KNaC 4 H 4 6 + H 2 + CO, 

Carbonate Acid tartrate of Tartrate of potas- Water. Carbonic 

of sodium. potassium. sium and sodium. acic gas 

Crystals of Rochelle salt are usually halves of colorless, trans- 
parent, right rhombic prisms, slightly efflorescent in dry air, soluble 
in five parts of boiling water. Tartrate of potassium is slightly 
deliquescent, soluble in about four parts of boiliDg water. 

Equivalent Weights of Tartaric Acid, Carbonate of Potassium, 
Bicarbonate of Potassium, Carbonate of Sodium, Bicarbonate 
of Sodium, and Carbonates of Ammonium and Magnesium ; 
repeated for 20 parts of each (and, incidentally, for other pro- 
portions). 



Tart. Acid 

Carb. Potas 

Bicarb. Pot 

Carb. Soda (cryst.). 

Bicarb. Soda 

Carb. Amnion 

Carb. Magnes 



H 2 C 4 H 4 6 = 150 

K 2 C0 3 (of 84 per cent.). = 164 

2(KHC0 3 ) = 200 

Na 2 CO 3 ,10H 2 O = 286 

2(NaHC0 3 ) = 168 

(N 3 H n C 2 3 )-s-3x2... = 105 
(MgC0 3 ) 3 Mg2H0,4H 2 O. = 95.5 



•20 


ISi 


15 


101 


m 


2S| 


22 


20 


16i 


111 


19| 


31| 


2Gf 


244. 


20 


14 


3f 


38± 


38 


24| 


28^ 


20 


34 


54£ 


22| 


20 


16| 


11* 20 


32 


14 


12* 


lOt 


U\ 121 


-° 


XI 


m 


9* 


&i 


1U 


18| 

1 



Thus 20 parts (grains or other weights) of tartaric acid neutralize 
22 of carbonate of potassium, 26f of bicarbonate of potassium, 38 
of carbonate of«sodium, 22J of bicarbonate of sodium, 14 of car- 
bonate of ammonium, or 12f of carbonate of magnesium. Other 
quantities of tartaric acid (18J-, 15, 10$, 16f , 28$, 31$) saturate the 
amounts of salts mentioned in the other columns, and vice versa. 
A similar Table for Citric Acid will be found on page 322, and for 
both acids in the Appendix. These Tables afford good illustrations 
of the laws of chemical combination (page 48). The reader should 
verify a few of the numbers by calculation from the atomic weights 
of the elements concerned in the reactions, remembering that the 
salts formed are considered to be neutral in constitution. In med- 
ical practice effervescing saline draughts are often designedly pre- 
scribed to contain an amount of acid or alkali considerably in excess 
of the proportions required for perfect neutrality. 

A common form of Seidlitz Powder consists of 3 parts of Rochelle 
salt (120 grains) with 1 (40 grains) of acid carbonate of sodium (the 
mixture usually wrapped in blue paper), and 1 (40 grains) of tartaric 
acid (wrapped in white paper). When administered, the one powder 
is dissolved in a tumbler rather more than half full of water, the 
other added, and the mixture drank during effervescence. It will be 
seen that the salts swallowed are tartrate of potassium and sodium 
(KNaC 4 H 3 6 , 4H 2 0), tartrate of sodium (Na 2 C 4 H 4 0g,2H 2 0), and acid 
tartrate of sodium or of potassium. The last-mentioned salt results 
because (for one reason) 11 \ per cent. (4J grains) of the tartaric acid 
i? in excess of the quantity necessary for the formation of neutral 



TARTRATES. 321 

tartrate of sodium ; and, for another reason, while carbonic acid re- 
mains in great excess, a neutral tartrate containing potassium maj 
be converted more or less into acid tartrate of potassium and bicar- 
bonate. This amount of acid salt gives, according to the taste of 
some persons, agreeable acidity to the draught. The United States 
formula (Pulvis Effervescens Compositus, U. S. P.) includes rather 
less tartaric acid, so that only neutral salts are formed, and the 
occurrence or permanent occurrence of the gritty acid tartrate of 
potassium avoided. 

" Double " Seidlitz Powder contains a double dose of Rochelle salt. 

Analytical Reactions (Tests.) 

First Analytical Reaction. — To solution of any normal tar- 
trate, or tartaric acid made neutral by solution of soda, add 
solution of chloride of calcium ; a white precipitate, tartrate of 
calcium (CaC 4 H 4 6 ,4H 2 0), falls. Collect the precipitate on a 
filter, wash, place a small quantity in a test-tube, and add solu- 
tion of potash ; on stirring the mixture the precipitate dissolves. 
Heat the solution ; the tartrate of calcium is again precipitated. 

In the above reaction a fair amount of the chloride of cal- 
cium solution should be added at once, and the whole test per- 
formed without delay, or the calcium tartrate will assume a 
crystalline character, and be with difficulty dissolved by the 
potash. 

The -solubility of tartrate of calcium in cold *potash solution 
enables the analyst to distinguish between tartrates and citrates, 
otherwise a difficult matter. Citrate of calcium is not soluble, or 
only to a very slight extent, in the alkali. The absence of much 
ammoniacal salt must be insured, citrate as well as tartrate of cal- 
cium being soluble in solutions of salts of ammonium. 

Second Analytical Reaction. — Acidulate a solution of a tar- 
trate with acetic acid, add acetate of potassium, and well stir 
the mixture ; a crystalline precipitate of acid tartrate of potas- 
sium slowly separates. 

This reaction is not applicable in testing for very small quantities 
of tartrates, the acid tartrate of potassium being not altogether 
insoluble. The precipitate being insoluble in alcohol, however, the 

addition of spirit of wine vendors the test far more delicate. One 
part of acid should yield \\ of salt. 

Third Analytical Reaction. — To a neutral solution of a tar- 
trate add solution of nitrate of silver ; a white precipitate o[' 
tartrate of silver, Ag 2 C 4 H 4 6 , falls. Boil the mixture; it 
blackens, owing to the reduction of the salt to metallic silver. 
Or, before boiling, add a drop, or less, of ammonia ; a mirror 
will form on the tube — adhering well to the glass if the tube 



322 SALTS OF ACIDULOUS RADICALS. 

was thoroughly cleansed. Even an insoluble tartrate, placed 
in a dry tube with a few fragments of nitrate of silver and a 
drop, or less, of ammonia added, gives a mirror-like character 
to each fragment of the silver salt when the tube is gently 
rotated some inches above a flame. 

Fourth Analytical Reaction. — To a neutral or alkaline so- 
lution of a tartrate add a few drops of solution of permanganate 
of potassium, and slowly heat the test-tube ; the color is dis- 
charged, an oxide of manganese being precipitated. Citrates 
only reduce the permanganate to green manganate. 

Other Reactions. — Tartrates heated with strong sulphuric- 
acid char immediately. Tartaric acid and the soluble tar- 
trates prevent the precipitation of ferric and other hydrates by 
alkalies, soluble double tartrates being formed (which on evap- 
oration yield liquids that do not crystallize, but, spread on sheets 
of glass, dry up to thin transparent plates or scales). The 
Ferri et Potassii Tartras, U. S. P. (Ferrum Tartar atum, B. P.), 

is a preparation of this kind. Tartrates decompose when 

heated, carbonates being formed and carbon set free, the gaseous 
products having a peculiar, more or less characteristic smell, 
lesembling that of burnt sugar. 



QUESTIONS AND EXERCISES. 

546. State the origin of tartaric acid and other tartrates, and 
explain the deposition of argol, crude acid tartrate of potassium, 
during the manufacture of wine. 

547. What is the chemical formula and what are the characters 
of "cream of tartar"? 

548. Mention the formula and quantivalence of the tartaric 
radical. 

549. Write formulae of normal, acid, and double tartrates, tartar- 
emetic being treated as an oxytartrate of antimony with tartrate of 
potassium. 

550. Give equations or diagrams illustrative of the production of 
tartaric acid from cream of tartar. 

551. By what general process may normal or double tartrates bo 
obtained from acid tartrate of potassium ? 

552. Work out sums proving the correctness of some of the fig- 
ures given on p. 320 as showing the saturating power of tartaric 
acid for various quantities of different carbonates, and give dia- 
grams or equations of the reactions. 

553. State the names and work sums showing the quantities of 
the salts resulting from the admixture of 120 grains of tartrate of 
potassium and sodium, 40 grains of acid carbonate of sodium, and 
40 grains of tartaric acid (Seidlitz powder). 

554. Enumerate the tests for tartrates, and explain the effects of 
heat on tartrates of the metals. 



CITRATES. 323 

CITRIC ACID AND OTHER CITRATES. 

Formula of Citric Acid H 3 C 6 H 5 7 ,Il20. Molecular weight 210. 

Source. — Citric Acid (Acidum Citricum, U. S. P.) exists in the 
juice of the gooseberry, currant, cherry, strawberry, raspberry 
(Rubus, U. S. P.), and many other fruits, and in other parts of 
plants. The pulp of the fruit of Tamarindus indica {Tamarindus, 
U. S. P.) contains from 1 to 12 per cent, (in addition to 1.5 of tar- 
taric acid, 5 of malic acid, and 3 per cent, of acid tartrate of potas- 
sium). But it is from the lemon or lime that the acid of commerce 
is usually obtained. For this purpose concentrated lemon-juice is 
exported from Sicily, concentrated bergamot juice from the Cala- 
brian coast of South Italy, and concentrated lime-juice from the 
West Indies. The lime-fruit from Citrus bergamia is official in the 
Pharmacopoeia of India. 

Process. — The British Pharmacopoeia directs that the hot lemon- 
juice (4 pints) be saturated by powdered chalk, that is, whiting (4J 
ounces), the resulting citrate of calcium collected on a filter, washed 
with hot water till the liquor passes from it colorless (by which not 
only the coloring-matter, but the mucilage, sugar, and other con- 
stituents of the juice are got rid of), then mixed with cold water 
(1 pint) decomposed by sulphuric acid (2J fluidounces in 1J pints of 
water), the mixture boiled for half an hour, filtered, the solution 
evaporated to a density of 1.21, set aside for 24 hours, then poured 
off from any deposit of crystalline sulphate of calcium, further con- 
centrated, and set aside to crystallize. If the quantity of citrate of 
calcium to be decomposed is indefinite, the sulphuric acid may be 
added until a little of the supernatant fluid gives, after a minute or 
two, a precipitate with solution of chloride of calcium. The con- 
centrated citric solution generally crystallizes very slowly. Shaken 
violently, however, in a bottle, with a granule or two of solid acid, 
it quickly yields its citric acid in a pulverulent form, and this, 
drained and reclissolved in a very small quantity of hot water, yields 
crystals fairly quickly (Warington). 

2H 3 C 6 H 5 7 + 3CaC0 3 = Ca 3 2C 6 H 5 7 + 3H,0 + 3C0 2 

Citric acid Carbonate of Citrate of Water. Carbonic 

(impure). calcium. calcium. acid gas. 

Ca ;! 2C 6 H 5 7 + 3H 2 S0 4 = 2II 3 C 6 H 5 7 + 3CaS0 4 

Citrate of Sulphuric Citric acid Sulphate of 

calcium. acid. (pure). calcium. 

Quantivalence. — The elements represented by the formula OJT^O. 
are those characteristic of citrates. They form a trivalent group- 
ing ; hence three classes of salts may exist — one, two, or throe 
atoms of the basylous hydrogen in the acid, H 3 C 6 H 6 7 , being dis- 
placed by equivalent proportions of other basylous radicals. 

Citric acid itself is the only citric compound oi' much direct im- 
portance to the pharmacist. It usually occurs in colorless crystals 
soluble in half their weight of boiling and throe-fourths o( cold 
water, less soluble in spirit, and insoluble in ether. A solution o( 



324 



SALTS OF ACIDULOUS RADICALS. 



about 34 grains in 1 ounce of water forms a sort of artificial lemon 
juice. Citrates heated with strong sulphuric acid to about 212° F. 
evolve carbonic oxide gas, and at higher temperatures acetone and 
carbonic acid gas. 

The artificial production of citric acid has been accomplished by 
Grimaux and Adam, who starting with glycerin, produce certain 
chloro- and cyano-derivatives, and ultimately citric acid itself. 

Action of Heat on Citric Acid. — Citric acid slowly heated first loses 
its water of crystallization ; afterwards (at 347° F.) the elements of 
another molecule of water are evolved and a residue obtained from 
which ether extracts aconitic acid (H 3 C 6 H 3 6 ), identical with the 
aconitic acid (and the acid first termed equisetic) in various species 
of Aconitum and Equisetum. 

The official Lemon Juice (Limonis Succus, U. S. P.) is to be freshly 
expressed from the ripe fruit, and to contain about 7 per cent, of 
citric acid. Lime Juice contains an average of 7.84 per cent, of citric 
acid, rarely rising to 10 per cent., and very seldom falling to 7 per 
cent. Containing but little sugar and mucilage, it requires no addi- 
tion of spirit to preserve it. The acidity may be ascertained by 
adding solution of potash or soda (the strength of which has been 
previously determined with pure crystals of citric acid) till red litmus- 
paper is fairly turned blue. Before applying this test to commercial 
specimens, the absence of notable quantities of sulphuric, hydro- 
chloric, acetic, tartaric, or other acid must be insured by application 
of appropriate reagents. (See also "Lemon Juice," in Index.) 

3Iistura Potassii Citratis, U. S. P., is lemon-juice completely 
neutralized by bicarbonate of potassium. It is a slightly impure but 
flavored solution of citrate of potassium. 

Lime Juice, as imported into England, contains an average of 7.84 
per cent, of citric acid, rarely rising to 10 per cent., and very seldom 
falling to 7 per cent. Containing but little sugar and mucilage, it 
requires no addition of spirit to preserve it. 

Lemon juice requires about 40 per cent, of proof spirit to prevent 
fermentation (Conroy). 

Equivalent Weights of Citric Acid, Carbonate of Potassium, 
Bicarbonate of Potassium, Carbonate of Sodium, Bicarbonate of 
Sodium, and Carbonates of Ammonium and Magnesium ; repeated 
for 20 parts of each (and incidentally, for other proportions). 





A 3 C 6 H 5 7 ,H 2 = 210 

(K„C0 3 ,of 84p.ct.)n-2x3 = 240* 


20 


17 


14 


9| 


16! 


26| 


29| 




23* 


•20 


16* 


11* 


195| 


31* 


34* 


Bicarb. Pot 


3(KHC0 3 ) =300 


28* 


24* 


20 


14 


24 


38* 


415 


Carb. Sod. (cryst)... 


(Na 2 CO 3 ,10H 2 O)^2X3... = 429 


40 


34J 


28| 


20 


34} 


5U 


GO 


Bicarb. Sod 


3(NaHC0 3 ) = 252 


24 


20* 


16| 


HI 


20 


32 


35 


Carb. Amnion 


(N 3 H 11 C 2 O s --3X2 = 157 


lo 


m 


10* 


7* 


12! 


20 


21| 


Carb. Magnes 


(MgC0 3 ) 3 Mg2HO,4H„0 

-=-8><3 = 143* 


lUi 


in 


9* 


6i 


in 


184 


20 



CITRATES. 325 

Thus 20 parts (grains or other weights) of citric acid neutralize 
23| of carbonate of potassium, 28 \ of bicarbonate of potassium, 40 
of carbonate of sodium, 24 of bicarbonate of sodium, 16f of carbo- 
nate of ammonium, or 15 of carb. of magnesium. Other quantities 
of citric acid (17, 14, 9f , 16f , 26|, 29j) saturate the amount of salts 
mentioned in the other columns, and vice versa. 

This Table, the similar one for tartaric acid (p. 320), and that for 
both acids (vide Appendix) afford good illustrations of some of the 
laws of chemical combination (p. 47). The reader should verify a 
few of the numbers by calculation from the atomic weights of the 
elements concerned in the reactions, remembering that the salts 
formed are considered to be neutral in constitution. In medical 
practice, effervescing saline draughts are often designedly prescribed 
to contain an amount of acid or alkali considerably in excess of the 
proportions required for perfect neutrality. 

Analytical Reactions (Tests). 

First Analytical Reaction. — To a dilute solution of any 
neutral citrate, or citric acid carefully neutralized by alkali, 
add solution of chloride of calcium and boil ; a white pre- 
cipitate, citrate of calcium (Ca 3 2C 6 H 5 7 ), falls. Treat the pre- 
cipitate as for tartrate of calcium (p. 321) ; it is not percepti- 
bly dissolved by the potash. 

A mixture of citrates and tartrates can be separated by this reac- 
tion. They are precipitated as calcium salts, and the rapidly washed 
precipitate mixed with solution of potash, diluted, and filtered ; the 
filtrate contains the tartrate, which is shown to be present by repre- 
cipitation on boiling. The precipitate still on the filter is washed, 
dissolved in solution of chloride of ammonium, and the solution 
boiled 5 the citrate of calcium is reprecipitated. The presence of 
much sugar interferes with this reaction. A dilute solution of a 
citrate is not precipitated by chloride of calcium until the liquid is 
heated ; precipitation from a strong solution, also, is not thoroughly 
complete without ebullition of the mixture. This reaction is not 
thoroughly satisfactory, citrate of calcium being slightly soluble in 
alkalies, in the solutions of salts produced in the reaction, and, to a 
very slight extent, even in cold water. It is readily soluble in acetic 
acid. 

Second Analytical Reaction. — To a neutral solution of a 
citrate add solution of nitrate of silver; a white precipitate of 
citrate of silver (Ag 3 C 6 H 5 T ) falls. Boil the mixture ; the pre- 
cipitate docs not turn black as a tartrate of silver does, or only 
after long boiling. 

Ihird Analytical Reaction. — To a neutral or alkaline solu- 
tion of a citrate add a few drops of solution of permanganate 
of potassium and slowly heat the test-tube ; reduction to man- 



326 SALTS OF ACIDULOUS RADICALS. 

ganate only occurs, a green or reddish-green solution resulting. 
Tartrates reduce the permanganate entirely. 

Other Analytical Reactions — Citric acid forms no precipitate 
corresponding with the acid tartrate of potassium. Lime- 
water, in excess, gives no precipitate with citric acid or citrates, 
unless the solution is boiled, citrate of calcium being slightly 
soluble in cold but not in hot water ; it usually precipitates tar- 
trates in the cold. Citrates, when heated with strong sul- 
phuric acid, do not char immediately. Citric acid and 

citrates prevent the precipitation of oxide of iron by alkalies, 
soluble double compounds being formed. The Ferri et Ammo- 

nii Citras, U. S. P., is a preparation of this kind. Metallic 

citrates decompose when heated, carbonates being formed and 
carbon set free : the odor of the gaseous products is not so 

characteristic as that of tartrates. According to Cailletet, a 

cold saturated solution of red chromate of potassium turns a 
solution of tartaric acid dark brown, carbonic acid gas being 
evolved, while a solution of citric acid only slowly becomes of 
a light brown. 

Pusctis Test for the Detection of Tartaric Acid in Citric Acid 
depends on the well-known difference in the action of sulphuric 
acid on tartaric action and citric acid. It consists in adding to 
1 gramme of powdered citric acid in a dry test-tube 10 grammes 
of strong pure (colorless) sulphuric acid, and keeping the tube 
containing the mixture immersed in boiling water for an hour. 
The citric acid dissolves with the evolution of gas and frothing 
to form a lemon-colored liquid ; and if the sample be pure, this 
color undergoes no change within half an hour, but if as much 
as half per cent, of tartaric acid be present, the lemon color 
becomes brownish within that time, and in an hour the mixture 
a red brown. 



QUESTIONS AND EXERCISES. 

555. What is the source of citric acid ? 

556. Describe the method by which citric acid is prepared, giving 
diagrams. 

557. Illustrate by formulae the various classes of tartrates and 
citrates. 

558. State the average proportion of citric acid in lemon-juice. 

559. Work out the sums proving the correctness of some of the 
figures given on page 324 as showing the saturating-power of citric 
acid for various carbonates. 

560. What are the tests for citrates ? 

561. How are the tartrates separated from citrates? 






PHOSPHATES. 327 

PHOSPHORIC ACID AND OTHER PHOSPHATES. 

Formula of Phosphoric Acid H 3 P0 4 . Molecular weight 98. 

Source. — The source of the ordinary normal phosphates and of 
phosphorus itself {Phosphorus, U. S. P.) is the normal phosphate 
of calcium (Ca 3 2P0 4 ). It is the chief constituent of the bones of 
animals, being derived from the plants on which they feed, plants 
again obtaining it from the soil. Compounds of phosphorus are 
also met with in the brain, nerves, muscles, blood, saliva, and, ac- 
cording to Kirkes, even in tissues so simple that one must assume 
that the compounds are necessary constituents of the substance of 
the primary cell. They escape from the system both in the urine 
and in the faeces. 

Process. — Phosphorus (P = 31) is obtained from bones by the 
following processes : The bones are burnt to remove all traces of 
animal matter. The resulting bone-earth is treated with sulphuric 
acid and water, by which an acid phosphate of calcium (CaII 4 2P0 4 ), 
often called superphosphate of lime, is produced : — 

Ca 3 2P0 4 + 2H 2 S0 4 = CaH 4 2P0 4 + 2CaS0 4 . 

The acid phosphate (strained from the sulphate and evaporated to 
dryness) is mixed with charcoal and sand, and heated to dull red- 
ness in an iron pot. At this stage water escapes and metaphosphate 
of calcium (Ca2P0 3 , see Index) remains : — 

CaH 4 2P0 4 = Ca2P0 3 + 2II 2 0. 

The mixture is then transferred to a retort, and distilled at a strong 
red heat 5 a silicate of calcium (CaSi0 3 ) is formed and remains in 
the retort, phosphorus vapor is evolved and condensed under water, 
and carbonic oxide gas escapes : — 

2(Ca2P0 3 ) + 2Si0 2 + C 10 = 2CaSi0 3 + 10CO + P 4 . 

The phosphorus is purified by melting under water containing 
sulphuric acid and red chromate of potassium. 

Properties. — Phosphorus is a " semi-transparent, colorless, wax- 
like solid (in sticks or cakes), which emits white vapors when ex- 
posed to the air. Specific gravity 1. 77. It is soft and flexible at 
common temperatures, melts at 110° F., ignites in the air at a tem- 
perature a little above its melting-point, burning with a luminous 
flame and producing dense white fumes. It is very poisonous. In- 
soluble in water, but soluble in ether and in boiling oil of turpen- 
tine," also in bisulphide of carbon. It is soluble in oil which has 
been previously heated for a short time to about 482° F. to expel 
moisture: 1 part in 90 parts of dried almond oil with 9 parts of 
ether constituting Phosphorated Oil, Oleum Phosphoratum, V. S. P. 
A mixture, or rather a solution, of phosphorus in chloroform, mixed 
with althea, acacia, and glycerin, forms the official Phosphorus Pills 
(Pilulce Phosphor/, U. S. P.). 

Granulated or pulverulent phosphorus is obtained bv placing a 
portion under equal parts of spirit and water in a bottle, standing 



328 SALTS OF ACIDULOUS RADICALS. 

the bottle in warm water till the phosphorus melts, then inserting 
the stopper (glass, not cork), and shaking the whole till cold. 

Red or Amorphous Phosphorus. — Ordinary phosphorus kept at a 
temperature of about 450° F., in an atmosphere from which air 
is excluded, becomes red, opaque, insoluble in liquids in which 
ordinary phosphorus is soluble, oxidizes extremely slowly, and 
only ignites when heated to near 500° F. It is used in the 
manufacture of several varieties of lucifer matches, not emitting 
the poisonous, jaw-destroying fumes given by ordinary phos- 
phorus. 

Quantwalence. — The atom of phosphorus is quinquivalent, as seen 
in the pentachloride (PC1 5 ) and oxychloride (PC1 3 0) ; but it often 
exhibits trivalent activity, as seen in the trichloride (PC1 3 ) and tri- 
hydride (PH 3 ). 

Phosphide of Zinc, Zn 3 P 2 {Zinci Phosphidum, U. S. P.), occurs 
as a grayish-black powder or in crystalline fragments having a 
metallic lustre. It may be obtained by throwing phosphorus upon 
melted zinc. 

Molecular Weight. — Phosphorus is an exception to the rule that 
the atomic weights (in grains, grammes, etc.) of elements occupy 
similar volumes of vapor at similar temperatures, the equivalent 
weight of phosphorus (31) only giving half such a volume. Hence 
while the molecular weights, that is, double the atomic weights, 
of oxygen (0 2 = 32), hydrogen (H 2 = 2), nitrogen (N 2 = 28), etc., 
give a similar bulk of vapor at any given temperature, the double 
atomic weight of phosphorus (P 2 = 62) only gives half this bulk ; 
that is, four times the atomic weight of phosphorus must be taken 
to obtain the whole bulk. It would appear therefore that the mole- 
cule of phosphorus contains four atoms (P 4 =124). As with sul- 
phur, however, phosphorus in the state ordinarily known to us may 
be abnormal, and conditions yet be found in which the molecular 
weight is double the atomic weight. 

Phosphoric Acid. 
The chief use of phosphorus in pharmacy is the formation 
of Diluted Phosphoric Acid. Phosphorus is boiled with nitric 
acid and water until dissolved. The solution, evaporated to a 
low bulk to remove nitrous compounds, and diluted so as to 
contain 50 per cent, of acid (H 3 P0 4 ), constitutes the Acidum 
Fhosphoricum, U. S. P., a colorless liquid of specific gravity 
1.347. If the necessary appliances are at hand, an ounce or 
two of this acid may be prepared by the official process as 
follows : Boil together, in a retort attached to a Liebig's con- 
denser, 160 grains of phosphorus, 1000 grains of the official 
nitric acid, and 1000 grains of water. When about 1 oz. of 
water has distilled over, it should be returned to the retort, 
and the operation repeated until the phosphorus has dis- 
appeared. 



PHOSPHATES. 



329 






3P 4 + 2OHNO3 + 8H 2 = 12H 3 P0 4 + 20NO 

Phos- Nitric acid. Water. Phosphoric Nitric 

phorus. acid. oxide. 

The liquid remaining in the retort is then transferred to a dish 
(preferably of platinum), evaporated down to about half an 
ounce, and, lastly, diluted with distilled water until the prod- 
uct weighs 1000 grains. 

One part, by weight, of the official phosphoric acid with 
four of water yields Acidum Phosphoricum Dilutum, U. S. P. 
It contains 10 per cent, of H 3 P0 4 ; sp. gr. 1.057. 

The use of the water in the former part of this process is to mode- 
rate the reaction. Strong hot nitric acid oxidizes phosphorus with 
almost explosive rapidity, hence the acid must be diluted in the first 
instance, and be rediluted, from time to time, to prevent its becom- 
ing too strong by loss of water. Time is saved by using a strong 
acid, but in that case constant supervision is necessary in order that 
water may be added, or the temperature otherwise reduced, when the 
action becomes too violent. Deficiency of nitric acid must also be 
avoided, or some phosphorous acid (H 2 PH0 3 ) will be formed. 

Markoe, also, to economize time, modifies the process by adding, 
for every ounce of phosphorus, four or five grains of iodine, and, drop 
by drop, twenty-five or thirty drops of bromine. The iodine and 
bromine unite with the phosphorus with a readiness or even violence 
that would be explosive if not controlled by the presence of the cold 
fluid — further cooled, if necessary, by immersing the vessel in cold 
water. Iodide of phosphorus (PI 5 ) and bromide of phosphorus 
(PBr 5 ) are at once formed. These, in the presence of water, imme- 
diately yield hydriodic and hydrobromic acids (HI, HBr) and phos- 
phoric acid. The nitric acid attacks the 
hydriodic and hydrobromic acids, forming 
the lower oxides of nitrogen, which escape 
as gas, water, and free iodine and bromine. 
The latter unite with more phosphorus, and 
the reactions are repeated. This carrying 
power of a little iodine or bromine, or both, 
would perhaps be indefinitely prolonged if no 
vapor of these elements or their acids escaped 
with the gases. The phosphorus having dis- 
appeared, excess of nitric acid is got rid of 
roughly by dropping in clean rags or paper 
(nitric oxide, carbonic acid gas, and water 
being formed), and the last portions by adding 
oxalic acid (which even still more readily yields 
similar products). Evaporation to a syrupy 
consistence finally removes all traces of iodine, 
bromine, oxalic acid, and moisture. The prod- 
uct is then diluted to any required extent. 

Experimental Process. — A flask, in the neck of which a funnel is 
inserted, and a second funnel inverted, so that its mouth rests with- 
in the mouth of the first, is an efficient and convenient arrangement 
28* 



Fig. 40. 




330 SALTS OF ACIDULOUS RADICALS. 

of apparatus for this process, especially if the operation be con- 
ducted slowly. 

Solution of phosphoric acid evaporated to a specific gravity of 1.850 
yields a mass of prismatic crystals of H 3 P0 4 , especially if a crystal or 
two be dropped into the fluid (Cooper). Further evaporated, it leaves 
a residue which melts at a low red heat, yielding pyrophosphoric 
acid, and, finally, metaphosphoric acid {Glacial Phosphoric Acid). 

Phosphoric acid is also easily made from amorphous phosphorus 
(Mattison). Also by dissolving phosphoric anhydride in water, and 
boiling with a little nitric acid to oxidize any lower acids of phos- 
phorus and to cause any lower phosphoric acids to take up the 
elements of water. 

Prepared from bones, phosphoric acid is apt to develop fungoid 
deposits (Jensen). Not more than traces of arsenicum or of sul- 
phur should be present in phosphorus, the former detected by sul- 
phuretted hydrogen and the latter by chloride of barium solution 
after the phosphorus has been converted by nitric acid into phos- 
phoric acid (U. S. P.). 

Quantivalence. — The elements represented by the formula P0 4 
are those characteristic of phosphates. The grouping is trivalent ; 
hence there may exist trimetaliic or normal phosphates (M / 3 P0 4 ), 
dimetallic acid phosphates (M^HPOJ, monometallic acid phosphates 
(jVFJTjPOJ, and, lastly, trihydric phosphate (II 3 P0 4 ) or common 
phosphoric acid. These are the ordinary phosphates or orthophos- 
phates met with in nature or used in pharmacy ; the rarer pyro- 
phosphates and metaphosphates, as well as the phosphites and 
hypophosphites, will be mentioned subsequently. 

Analytical Reactions (Tests). 

First Analytical Reaction. — To an aqueous solution of a 
phosphate (e. g. Na. 2 HP0 4 ) add solution of sulphate of mag- 
nesium with which chloride of ammonium and ammonia have 
been mixed ; a white crystalline precipitate of ammonio-mag- 
nesium phosphate falls (MgNH 4 P0 4 ). 

Chloride of ammonium is added to prevent the precipitation of 
hydrate of magnesium. Arseniates, which have close analogy to 
. phosphates, give a precipitate of similar character with the mag- 
nesium reagent. 

Second Analytical Reaction. — To an aqueous solution of a 
phosphate add solution of nitrate of silver ; light-yellow phos- 
phate of silver (Ag 3 P0 4 ) is precipitated completely if the mix- 
ture be neither acid nor alkaline. To a portion of the precipi- 
tate add ammonia ; it dissolves. To another portion add nitric 
acid ; it dissolves. By the former part of this reaction phos- 
phates may be distinguished from their close allies the arseni- 
ates, arseniate of silver being of a chocolate color. 

Third Analytical Reaction. — To solution (in a few drops 



PHOSPHATES. 331 

of acid) of a phosphate insoluble in water (e. g. Ca 3 2P0 4 ) add 
the acetate of an alkali-metal (easily made by adding to soda 
or ammonia in a test-tube excess of acetic acid), and then a 
drop or two of solution of perchloride of iron ; yellowish-white 
ferric phosphate (Fe 2 P0 4 ) is precipitated, insoluble in acetic 
acid. Too much of the ferric chloride must not.be added, or 
ferric acetate will be produced, in which ferric phosphate is to 
some extent soluble. 

To remove the whole of the phosphoric radical from the solu- 
tion, add ferric chloride so long as a precipitate is produced, 
and boil ; ferric phosphate and oxyacetate are precipitated. 

To obtain confirmatory evidence of the presence of phosphate 
in this precipitate, and to separate the phosphoric radical as a 
pure unmixed phosphate, collect the precipitate on a filter, 
wash, drop some solution of ammonia on it, then sulphydrate 
of ammonium, and finally wash with water ; black ferrous sul- 
phide remains on the filter, while phosphate of ammonium 
occurs in the filtrate. To the filtrate add a mixture of solutions 
of sulphate of magnesium and chloride of ammonium, and 
well stir ; ammonio-magnesian phosphate is precipitated. 

Fourth Analytical Reaction. — To diluted nitric acid add a 
little phosphate of calcium (or any other phosphate), and then 
solution of molybdate of ammonium, and gently heat ; a yel- 
low precipitate falls. 

This precipitate contains what is termed phospho-molybdic acid, 
but is a compound of molybdic acid with phosphoric acid (about 4 
per cent, of H 3 P0 4 ) and ammonia (nearly 7 per cent.). 

Molybdate of ammonium is obtained by roasting the native 
sulphide of molybdenum (MoS 2 ) to molybdic oxide or anhydride 
(Mo0 3 ), dissolving the latter in water, adding ammonia, evaporating, 
and crystallizing. 

Molybdates having the following formulas (M = 1 univalent atom 
of any metal) have been obtained: M 2 Mo0 4 ; MHMo0 4 ; MHMo0 4 , 
H 2 Mo0 4 . According to Carrington, commercial molybdate of am- 
monium is commonly the intermediate of these three salts. Molyb- 
date of sodium has the formula Na 2 Mo0 4 ,H 2 0. 

Note. — The foregoing two reactions are useful in the analysis of 
bone-earth, other earthy phosphates, phosphate of iron, and all 
phosphates insoluble in water. Only arsehiates give similar appear- 
ances ; but the acid solution of these may be decomposed by agitation 
with sulphurous acid and subsequent treatment with sulphuretted 
hydrogen, arsenious sulphide, As 2 S 3 , being then precipitated. 

# Other Analytical Reactions.— Solutions of barium and cal- 
cium salts give, with aqueous solutions of phosphates, white 
precipitates of the respective phosphates BaHP0 4j or Ba 3 2P0 4 , 
and OallPO.,, or Ca 3 2P0 4 , all of which are soluble in aeetie and 
the stronger acids. 



332 SALTS OF ACIDULOUS RADICALS. 

QUESTIONS AND EXERCISES. 

562. State the source of phosphorus. 

563. Give equations or diagrams explanatory of the isolation of 
phosphorus from its natural compounds. 

564. What is the composition of farmers' " superphosphate," and 
how is it prepared ? 

565. Enumerate the properties of phosphorus. 

566. Mention some solvents of phosphorus. 

567. How are the varieties of official Phosphoric Acid made? 

568. Describe the precautions necessary to be observed in making 
this acid. 

569. What are the strengths of the official acids? 

570. Write formulae illustrative of all classes of orthophosphates. 

571. Mention the chief tests for soluble and insoluble phosphates. 

572. By what reactions may phosphates be distinguished from 
arseniates? 



Vanadium, V. 51.3, is a very rare element, and is here men- 
tioned only because of its exceedingly interesting relationship 
to nitrogen, phosphorus, and arsenicum. Discovered but not 
isolated by Sefstrom, and its compounds investigated by Berze- 
lius, it has only of late years been obtained in the free state 
and fully studied by Boscoe. 



Oxides of Nitrogen. 

N 2 5 , NA, NA, NA, NA 

Orthophosphates B 3 T0 4 
Pyrophosphates B/P 2 7 
Metaphosphates B'P0 3 



Oxides of Vanadium. 

VA, VA VA, VA, VA 

Orthovanadates B/VO^ 
Pyrovanaclates B/V 2 7 
Metavanadates B'V0 3 



Isomorphous Minerals. 
Apatite 3(Ca 3 2P0 4 ),CaFl 2 

Pyromorphite 3(Pb 3 2P0 4 ),PbCl 2 
Mimetesite 3(Pb 3 2AsO0,PbCl 2 
Vanadinite 3(Pb 3 2V0 4 ),PbCl 2 

BORIC ACID AND OTHER BORATES. 

Formula of Boric Acid H 3 B0 3 . Molecular weight 62. 

The composition of artificial boric acid, sometimes termed boracic 
acid, is expressed by the formula H 3 B0 3 {Acidum Boricum, U. S. P.) ; 
but at a temperature of 212° F. this body loses the elements of water 
and yields metaboric acid, HB0 2 , which at higher temperatures be- 
comes boric anhydride (B 2 3 ). The latter acid exists in the jets of 
steam (fumerolles or suffioni) that issue from the earth in some dis- 
tricts of Tuscany and collects in the water of the lagoni (lagoons or 
little lakes) formed at the orifices of the steam-channels. This acid 



BORATES. 333 

liquid, evaporated by aid of the waste natural steam and neutralized 
by carbonate of sodium, gives common borax (2NaB0 2 ,2HB0 2 ,9H 2 0), 
possibly an acid metaborate of sodium with water of crystallization, 
or, possibly, a metaborate of sodium with boric anhydride (2NaB0 2 ,- 
B 2 O 3 ,10H 2 O). It occurs "in transparent colorless crystals, sometimes 
slightly effloresced, with a weak alkaline reaction ; insoluble in recti- 
fied spirit, soluble in water." Native borax, or tincal, and other 
borates are also found in Thibet, in Nevada, Peru, Chili, and re- 
cently in California, in the Clear Lake district. The introduction of 
the natural borax from California has reduced the price to about one- 
half its former amount. This borax is represented as forming large 
portions of the crystalline bed of a dried-up lake. Fused borax 
readily dissolves metallic oxides, as will have been already noticed 
in testing for cobalt and manganese. Hence, besides its use in 
medicine (Sodii Boras, U. S. P.), it is employed as a flux in refining 
and other metallurgic and ceramic operations. 

Quantivalence. — The boric radical is trivalent (B0 3 /// ), the meta- 
boric, univalent (BO/). The element boron, like carbon, occurs in 
the amorphous, graphitoidal, and crystalline conditions. It is a 
trivalent element (B /7/ ), yielding definite salts, such as the chloride 
(BC1 3 ) and fluoride (BF 3 ). Its atomic weight is 11. 

Reactions. 

First Synthetical Reaction. — To a hot solution of a crystal of 
borax add a few drops of sulphuric acid and set aside ; on cool- 
ing, crystalline scales of boric acid (H 3 B0 3 ), Acidum Boricum, 
B. P., are deposited. They may be purified by collecting on a 
filter, slightly washing, drying, digesting in hot alcohol, filtering, 
and setting aside ; pure boric acid is deposited. The acid may also 
be recrystallized from water. Fifty grains dissolved in one ounce 
of rectified spirit constitute " Solution of Boric Acid," B. P. 

Boric acid is a very weak compound. Indeed, the alkalinity of 
borax is as great as if it contained no acidulous radical. The acid 
only slowly decomposes carbonates. Boric acid is said to be itself an 
antiseptic, but Endemann states that in preserving foods it acts by 
converting phosphates into acid phosphates, and that the latter are 
the antiseptic principles. 

Second Synthetical Reaction. — Mix together 1 part of boric 
acid, 4 of acid tartrate of potassium, and 10 or 20 of water ; 
evaporate to a syrupy consistence, spread on plates, and set 
aside for dry scales to form. The resulting substance is. in 
water, far more readily soluble than either of its constituents, 
and is known as boro-tartrate of potassium or soluble en am of 
tartar. The Prussian tartarus boraxatus differs from the fore- 
going French variety in containing 1 part of borax to 3 of arid 
tartrate of potassium. 



334 SALTS OF ACIDULOUS RADICALS. 

Analytical Reactions (Tests). 

First Analytical Reaction. — Dip a piece of turmeric-paper 
(paper soaked in tincture of turmeric tubers and dried) into a 
solution of boric acid ; it is colored brown-red, as by alkalies. 

The usual way of applying this test is as follows : Add to a solu 
tion of any borate a few drops of hydrochloric acid ; immerse half of 
a slip of turmeric-paper in the liquid, then remove the hydrochloric 
acid by drying the paper over a flame. Concentrated hydrochloric 
acid and ferric chloride produce a somewhat similar effect. 

Second Analytical Reaction. — To a fragment of a borate of 
metaborate (borax, for example) in a small dish or watch-glass 
add a drop of sulphuric acid, and then a little alcohol ; warm 
the mixture and set light to the spirit ; the resulting flame 
will be tinged of a greenish color at its edges by the volatilized 
boric acid or boric anhydride. 

The liquid should be well stirred while burning. Salts of copper 
and some metallic chlorides produce a somewhat similar color. The 
flame test may also be applied to a little of a mixture of the borax 
with strong sulphuric acid on a platinum wire. Glycerin may be 
used in place of sulphuric acid (lies), the reaction in this case being, 
according to Dunstan, the formation of borate of glyceryl, C 3 H 5 B0 3 , 
Water, and metaborate of sodium, the metaborate of glyceryl and 
water reacting immediately to form boric acid and glycerin. 

Other Analytical Reactions. — In solutions of borax barium 
salts give a white precipitate of barium metaborate (Ba2B0 2 ) 
soluble in acids and alkaline salts. Nitrate of silver gives 
metaborate of silver (AgB0 2 ) soluble in nitric acid and in 
ammonia. Chloride of calcium, if the solution is not too di^ 
lute, gives white borate of calcium. 



QUESTIONS AND EXERCISES. 

573. Illustrate the relation of vanadium to nitrogen by formulae of 
compounds of each element. 

574. Describe the preparation of borax. 

575. Give the formulae of boric acid, metaboric acid, and borax. 

576. Mention the tests for borates or metaborates. 



The foregoing acids and other salts contain the only acidulous 
radicals that are commonly met with in analysis or in ordinary 
medical or pharmaceutical operations. There are, however, many 
others which occasionally present themselves. The chief of these 
will now be shortly noticed ; they arc arranged in alphabetical order 
to facilitate reference. 



BENZOATES. 335 

SALTS OF RARER ACIDULOUS RADICALS. 

Anemonic Acid. — Pulsatilla, U. S. P., is the official name for the 
herbs of Anemone Pulsatilla, A. pratensis, and A. patens. These, 
together with several species of Ranunculus, on distillation with 
water yield a heavy, yellow, acrid oil, which, in contact with water, 
yields crystalline poisonous anemonin (C 15 H 12 6 ) and amorphous 
anemonic acid (C 15 H 14 7 ). 

Benzoic Acid (HC 7 H 5 2 ) and other Benzoates. — Slowly 
heat a fragment of benzoin (Gum benzoinum) (Benzoinum, 
U. S. P.) in a test-tube ; benzoic acid (Aci'dum Benzoicum, U. S. 
P.) rises in vapor and condenses in small, white, feathery plates 
and needles, on the cool sides of the tube. If the benzoin is 
first mixed with twice its weight of sand or roughly powdered 
pumice-stone, and the heat very cautiously applied, the product 
will be less likely to be burnt, and a larger quantity be yielded. 
By repeated sublimation 10 to 15 per cent, may be obtained. 

A more economical process is to boil the benzoin with one 
fourth of its weight of lime, filter, concentrate, decompose the 
solution of benzoate of calcium by hydrochloric acid, collect 
the precipitated benzoic acid, press between paper, dry and 
sublime in a tube or other vessel. 

2HC 7 H 5 2 + Ca2HO = Ca2C 7 H 5 2 + 2H 2 

Benzoic acid Hydrate of Benzoate of Water, 

(impure). calcium. calcium. 

Ca2C 7 H 5 2 + 2HC1 = CaCl 2 + 2HC 7 H 5 2 

Benzoate of Hydrochloric Chloride of Benzoic acid 

calcium. acid. calcium. (pure). 

There is always associated with the product a minute quantity of 
a mixture of volatile oils of agreeable odor, suggesting that of hay, 
and yielding, according to Jacobsen, methylbenzoate, guaiacol (meth- 
oxyeatechol), catechol, acetylguaiacol, benzyl benzoate, benzophenone, 
and benzoylguaiacol. 

Benzoic acid is also prepared on a large scale artificially from 
naphthalene, one of the crystalline by-products in the distillation of 
coal for gas. The naphthalene is oxidized by nitric acid to naphtlnilic 
or phthalic acid : — 

C 10 TT 8 + 40 2 = ITAI1A + H,(\0 4 

Naphthalene. Oxygen. Phtkalic acid. Oxalic acid. 

The phthalic acid is neutralized by lime, and the phthalate of calcium 
heated with hydrate of calcium in a covered vessel at a temperature 
of about 040° F. for several hours. Benzoate and carbonate of cal- 
cium are formed, and from the powder the benzoic acid is set free 
by action of hydrochloric acid. 

2CaC 8 H 4 4 |- Ca2HO == Ca2C 7 H 6 O a + 2CaC0 3 

Phthalateof Hydrate of Benzoateof Carbonate of 

calcium. calcium. calcium. calcium. 



336 SALTS OF RARER ACIDULOUS RADICALS. 

The crystalline deposit formed when essential oil of almonds, ben- 
zoic aldehyde, is exposed to the air is benzoic acid. 

2C 6 H 5 COH + 2 = 2C 6 H 5 COOH or 2HC 7 H 5 2 

Benzoic aldehyde. Oxygen. Benzoic acid. 

Pure sublimed benzoic acid is also obtained from hippuric acid (p. 
336). Such acid, if not thoroughly purified, may have an urinoid 
odor. Jacobsen prepares benzoic acid from benzotrichloride (tri- 
chloromethyl-benzene, C 6 H 5 CC1 3 ), one of the trichlortoluenes, by 
heating with glacial acetic acid and chloride of zinc. This acid, if 
not very highly purified, may give a green color to flame when placed 
on platinum wire with a little oxide of copper. In artificial benzoic 
acid the fragrant volatile oil characteristic of the natural acid is, of 
course, absent, while in some specimens the odor of oil of bitter 
almond may be detected. 

Benzoate of Ammonium. — To a little benzoic acid add a 
few drops of solution of ammonia ; it readily dissolves, form- 
ing benzoate of ammonium {Ammonii Benzoas, U. S. P.) 
(NH 4 C 7 H 5 2 )- 

HC 7 H 5 2 + NH 4 HO = NH 4 C 7 H 5 2 4- H 2 

Benzoic acid. Ammonia. Benzoate of Water, 

ammonium. 

On evaporation, acid crystals or, ammonia being added, neu- 
tral crystals of benzoate of ammonium are deposited. Benzoate 
of sodium (So^ii Benzoas, U. S. P.), NaC 7 H 5 2 ,H 2 0, may be 
similarly prepared. 

Properties. — Benzoic acid is also soluble in other alkaline 
liquids, forming benzoates. It is slightly soluble in cold water, 
more so in hot, and readily soluble in rectified spirits. It 
melts at 2-i8° F., and boils at 462°, volatilizing with only a 
slight residue. Heated with lime it yields benzene. It dis- 
solves in cold oil of vitriol without decomposition, is again 
deposited on dilution, and the traces of odoriferous and other 
substances present in the acid from benzoin only slightly color 
the fluid, even on gently warming. 

Tests for Benzoates. — To a portion of the above solution of 
benzoate of ammonium add a drop or two of sulphuric or hydro- 
chloric acid ; a white crystalline precipitate of benzoic acid 
separates. To another portion, carefully made neutral, add a 
drop or two of neutral solution of perchloride or persulphate 
of iron ; reddish ferric benzoate is precipitated. 

Cinnamic Acid r (C 8 H 7 COOH). — Benzoic acid is distinguished 
from an allied body, cinnamic acid (occurring in Balsams of 
Peru, Tolu, and Storax, and sometimes in Benzoin), by not 
yielding benzaldehyde (C 6 H 5 COOH) (oil of bitter almonds) 



BENZOATES. 337 

when distilled with chromic acid — that is, with a mixture of 
red chromate of potassium and sulphuric acid — or when rubbed 
with half its weight of permanganate of potassium. Old hard 
balsam of tolu yields it on boiling with lime and water and 
precipitating by hydrochloric acid. Jacobsen makes it arti- 
ficially by the prolonged reaction of glacial acetic acid and ben- 
zodichloride in the presence of chloride of zinc. 

Carminic Acid (C m H u 8 ). — This is the coloring principle (about 
ten per cent.) of the dried female Coccus Cacti, or cochineal ( Coccus, 
U. S. P.). The carmine of trade, when unadulterated (vide Phar- 
maceutical Journal, 1859-60, p. 546), is carminic acid united with 
two or three per cent, of alumina and lime, or, occasionally, of oxide 
of tin or alumen. It should be wholly soluble in solution of am- 
monia, giving an apparently clear rich purple fluid. Carmine, with 
French chalk, or starch, constitutes face-rouge or animal rouge. 

Merrick tests the relative value of several samples of cochineal or 
carmine by observing how much solution of permanganate of potas- 
sium is required to change the color of a decoction to faint pink. 
The silvery coating of cochineal is a wax, coccerin. 

Cetraric Acid (H 2 C 34 H S0 O ]6 ) is the bitter principle of Iceland 
moss (Cetraria, U. S. P.). In the lichen it is associated with much 
starch. 

Chrysophanic Acid (C u H 10 O 4 ). — This yellow acid is found in vari- 
ous species of rhubarb-root (Rheum, U. S. P.), and, under the name 
of parietinic acid, in various common yellow lichens. Kuble con- 
siders — DragendorfF also — that the chrysophanic acid of rhubarb is 
only produced when a glucoside, chrysophan, is acted on by a ferment 
in the presence of water. The formation of chrysophanic acid is 
probably in most, if not in all, cases preceded by the occurrence of 
chrysophan or an allied body. The author found it to form four- 
fifths of old " Chrysarobine," a name given by Kemp to the pith, 
etc. of a leguminous tree (Andira Araroba). Chrysarobine or 
crysarobin (Chrysarobinum, U. S. P.) is also known as Araroba 
Powder, Bahia Powder, Brazil Powder, Goa Powder, and Ring- 
worm Powder. Recently chrysarobin has been shown by Lieber- 
mann and Seidler to have the formula C 30 H 2ti O 7 ; this, by oxidation 
and elimination of water, yields the chrysophanic acid occurring in 
old chrysarobin. Chrysophanic acid may be obtained in crystals of 
of a goiden-yellow color, hence the name (from xpvabg, chrusos, gold, 
and (paivLd, phaino, I shine). Its synonyms are Rhaponticin, Rheic 
acid, Rlicin, Rheumin, Rheubarbaric acid, Rheubarbarin, Rumicin. 
Chrysophanic acid, actual or potential black, red-brown, and red 
resins (Aporetine, Phworetine, and Erythroretine), a bitter principle, 
and tannic acid, are considered to be the conjoint source of the 
therapeutic properties of rhubarb. Chrysophanic acid may also be 
obtained from several species of Rumex or Dock. ll Rumicin" is a 
name given to a preparation of the root of Rumex crispus, or Yellow 
Dock (Rumex, U. S. P.). Cascara Sagrada, or Sacred Hark (Rham- 
ni Purshiani Cortex, B. P.), according to Limousin, contains chrys- 
29 



338 SALTS OF RARER ACIDULOUS RADICALS. 

ophanic acid, a glucoside (?), and a ferment, and various resins are 
said to be present also. 

Emodin, C 15 H 10 O 5 , is, apparently, closely associated, chemically, 
with chrysophanic acid. It is obtained with chrysophanic acid in 
the preparation of the latter from rhubarb. It also occurs in Black 
Alder Bark {Rhamni FrangulcB Cortex, B. P.), according to Lieber- 
mann and Waldstein, is said to be derived, together with glucose, 
from frangulin, the glucoside of the dried bark. 

Cornic Acid, or Cornin. — This is, according to Geiger, the crys- 
talline bitter principle of the bark (Comus, U. S. P.) of Cornus fior- 
ida. A crystalline resin is also present. 

Cyanic Acid (HCyO) and other Cyanates. — The valu- 
able reducing power of cyanide of potassium (KCy) (or ferro- 
cyanide, K 4 Fcy) on metallic compounds is due to the avidity 
with which cyanate (KCyO) is formed. 

Process. — Fuse a few grains of cyanide of potassium in a 
small porcelain crucible, and add powdered oxide of lead ; a 
globule of metallic lead is at once set free, excess of the oxide 
converting the whole of the cyanide of potassium into cyanate 
of potassium. 

Urea. — Cyanate of potassium (KCNO), or, better, cyanate of lead 
(Pb2CNO), treated with sulphate of ammonium, yields cyanate of 
ammonium (NH 4 CNO) 5 and solution of cyanate of ammonium, 
when simply heated, changes to artificial urea (CH 4 N 2 0), the 
most important constituent of urine, and the chief form in which 
the nitrogen of food is eliminated from the animal system. The 
process will be more fully described subsequently in connection 
with Urea. 

Formic Acid (HCH0 2 ). — The red ant {Formica rufa) and several 
other insects, when irritated, eject a strongly acid, acrid liquid, hav- 
ing a composition expressed by the above formula, and which has 
appropriately received the name of formic acid ; it is also contained 
in the leaves of the stinging-nettle. (According to Church the sting 
of the wasp is alkaline.) 

Process. — It may be artificially prepared by heating equal 
weights of oxalic acid and glycerin to a temperature of from 
212° to 220° F. for fifteen hours, and then distilling the mix- 
ture with a considerable volume of water. The formic acid 
slowly passes over, the glycerin being regenerated. The dilute 
acid may be concentrated by neutralizing with carbonate of 
lead, filtering, evaporating to a small bulk, collecting the 
deposited crystalline formate of lead, drying, decomposing in a 
current of sulphuretted hydrogen, separating the resulting 
syrupy acid, and passing air through the product until all sul- 



CYANATES. 339 

phuretted hydrogen is removed. The following are the chief 
reactions : — 

C 3 H 5 3HO + H 2 CA = C s H 5 HOCA + 2H a O 

Glycerin. Oxalic Hydrato-oxalate Water, 

acid. of glyceryl. 

C,H 5 HOC 2 4 + 2H 2 = C 3 H 5 3HO + HCHO, + C0 2 

Hydrato-oxalate Water. Glycerin. Formic Carbonic 

of glyceryl. acid. anhydride. 

Formic acid may be instructively though not economically pre- 
pared by the oxidation of methylic alcohol (wood spirit), just as 
acetic acid and valerianic acid are obtained from ethylic alcohol and 
amylic alcohol respectively. 



}H 3 HO 


+ o 2 = 


= HCH0 2 


+ 


H 2 


Wood- 


Oxygen. 


Formic 




Water. 


spirit. 




acid. 







Tests. — Formic acid does not char when heated alone or with sul- 
phuric acid, but splits up into carbonic oxide gas and water. It 
is recognized by this property and by its reducing action on 
salts of gold, platinum, mercury, and silver. It is solid below 
32° F. 

Gallic Acid. — See Tannic Acid. 

Hemldesmic Acid. — The supposed active principle of hemi- 
desmus root {Hemidesmi radix, B. P.). 

Hippuric Acid (HC 9 H 8 N0 3 ) is a constituent of human urine 
(much increased on taking benzonic acid), but is prepared from the 
urine of the horse (hence the name, from Imfog, hippos, a horse), 
or, better, from that of the cow. To such urine add a little milk of 
lime, boil for a few minutes, remove precipitated phosphates by fil- 
tration, drop in hydrochloric acid until the liquid, after well stirring, 
is exactly neutral to test-paper, concentrate to about one-eighth the 
original bulk, and add excess of strong hydrochloric acid ; impure 
hippuric acid is deposited. From a solution of the impure acid in 
hot water chlorine gas removes the color, and the liquid deposits 
crystals of pure hippuric acid on cooling. 

Tests. — To a solution of hippurate add neutral solution of ferric 
chloride : a brown precipitate (ferric hippurate) results. Salts of 
silver and mercury give white precipitates. Heat hippuric acid in 
a test-tube ; it chars, benzoic acid sublimes, and vapors of charac- 
teristic odor are evolved ; they contain, amongst other bodies, hy- 
drocyanic acid and a substance smelling fomewhat like Tonka bean. 

The crystalline form of hippuric acid is characteristic ; it will be 

described in connection with the subject of urine. 



QUESTIONS AND EXERCISES. 

577. Give the preparation, composition, properties, and tests of 
benzoic acid, employing equations or diagrams. 



340 SALTS OF RARER ACIDULOUS RADICALS. 

578. What is the nature of carmine ? 

579. Name the bitter principle of Iceland moss. 

580. Mention the coloring principle of rhubarb. 

581. To what is rhubarb considered to owe its medicinal activity? 

582. How is cyanate of potassium prepared, how converted into 
an ammonium salt, and what are the relations of the latter to urea? 

583. Give the formulae of cyanic acid, cyanate of ammonium, and 
urea. 

584. What is the chemical formula of formic acid ? 

585. Describe the artificial production of formic acid. 

586. Describe the relation of formic acid to wood spirit, 

587. State the sources, characters, and tests of hippuric acid. 



Hvdroferrocyanic Acid (H 4 Fe // Cy 6 , or H 4 Fcy //// ) and other 
Ferrocyantdes. — The ferrocyanide of most interest is that of 
potassium (Potassii Ferrocyanidum, U. S. P.), the yellow prussiate 
of potash (K 4 FeC 6 N 6 ,3H 2 0), the formation of which was alluded to 
in connection with hydrocyanic acid (see page 278). It cannot be 
regarded as simply a double salt of cyanide of potassium with cyanide 
of iron (FeCy 2 ,4KCy), its chemical properties being entirely different 
from either of those substances ; moreover, unlike cyanide of potas- 
sium, it is not poisonous. Most of its reactions point to the conclu- 
sion that its iron and cyanogen are intimately united to form a 
definite quadrivalent radical appropriately termed ferrocyanogen 
(FeCy 6 , or Fey). One part of ferrocyanide of potassium in 20 of 
water forms the official " Solution of Ferrocyanide of Potas- 
sium, 1 ' B. P. 

Tests. — Many of the ferrocyanides are insoluble, and are 
therefore precipitated when solution of ferrocyanide of potas- 
sium is added to the various salts. Those of iron and copper, 
being of characteristic color, are adopted as tests of the pres- 
ence of the metals or of the ferrocyanogen, as the case 
may be. 

To solution of ferrocyanide of potassium add a ferric salt ; 
ferrocyanide of iron (Fe 4 Fcy 3 ) (Prussian blue) is precipitated. 

3K 4 Fcy + 2(Fe 2 3S0 4 ) = Fe 4 Fcy 3 + 6K 2 S0 4 . 

To another portion add solution of a copper salt ; reddish- 
brown ferrocyanide of copper (Cu 2 Fcy) is precipitated. 

Note. — The ferrocyanogen in ferrocyanide of potassium is broken 
up when the salt is heated with sulphuric acid, carbonic oxide 
being evolved if the acid is strong (that is, ordinary oil of vitriol 
— H 2 S0 4 with 3 to 4 per. cent of water), and hydrocyanic acid 
if weak : — 

K 4 FeC 6 N 6 ,3H 2 + 3H 2 + 6H 2 S0 4 = 2K 2 S0 4 + FeS0 4 
+ 3(NHJ 2 S0 4 + 6CO. 



FERRICYANIDES. 341 

2K 4 FeCy 6 + 6H 2 S0 4 + xH 2 = FeK 2 FeCy 6 + 6KHS0 4 
-f 6HCy + rH 2 0. 

Hydrocyanic Acid has already been described. (Vide p. 278.) 

Carbonic Oxide (CO). — Heat two or three fragments of ferrocy- 
anide of potassium with eight or ten times their weight of sulphuric 
acid, and as soon as the gas begins to be evolved remove the test- 
tube from the flame ; for the action, when once set up, proceeds 
somewhat tumultuously. Ignite the carbonic oxide at the mouth of 
the tube ; it burns with a pale blue flame, the product of combustion 
being carbonic acid gas (C0 2 ). 

Carbonic oxide is a direct poison. It is generated whenever coke, 
charcoal, or coal burns with an insufficient supply of air. Hence 
the danger of open fires in the more or less closed apartments of or- 
dinary dwellings. 

Carbonic oxide may also be obtained from oxalic acid. (Vide 
p. 316.) 

Hydroferricyanic Acid (H 6 Fe A// 2 Cy 12 , or H T 6 Fdcy VI ) and 
other Ferricyanides. — Pass chlorine gas slowly through 
solution of ferrocyanide of potassium until the liquid, after 
frequent shaking, ceases to give a blue precipitate, when a 
minute portion is taken out on the end of a glass rod and 
brought into contact with a drop of a dilute solution of a fer- 
ric salt ; it now contains ferricyanide of potassium (B. P.), 
(K 6 Fe /r/ 2 Cy 12 , or K I 6 Fdcy VI ), red prussiate of potash, as it is 
termed from the color of its crystals. Excess of chlorine must 
be carefully avoided, as chloride of cyanogen and other com- 
pounds are then formed. Such a result does not ensue if bro- 
mine be used instead of chlorine, but the process is, of course, 
more expensive. 

2K' 4 Fe"Cy' 6 + 01', == 2K'C1' + K' 6 Fe'" 2 Cy' 12 . 

Another Process. — To a cold solution of yellow prussiate of 
potash so much hydrochloric acid is added as will take two 
atoms of potassium from two molecules of the salt, and then a 
cold clear solution of bleaching-powder till ferric chloride gives 
no reaction. Any excess of acid is then neutralized with chalk 
and the solution evaporated to crystallization (Rhien). 

Note. — The removal of two atoms of potassium from the ferro- 
cyanide is the only change of composition that occurs ; but the 
ferrocyanogen is altered in quality, its iron passing from the ferrous 
to the ferric condition, from bivalent to fcrivalent activity, altered to 
a condition in which it no longer precipitates ferric salts, but, on 
the other hand, gives a dark-blue precipitate with ferrous salts. 
The radical is distinguished as ferricyanogen. 

Ferricyanide. of potassium may also be prepared by a modifica- 
tion of the foregoing method in which nascent instead of free chlorine 
29* 



342 SALTS OF RARER ACIDULOUS RADICALS. 

is employed (Wenzell). Take of Bichromate of Potassium 1 part, 
Ferrocyanide of Potassium Cryst. 5.72 parts, Hydrochloric Acid, of 
spec. grav. 1.16, 3 parts by weight, Water 60 parts. Dissolve the 
two salts in hot water, add the acid, heat to boiling, continuing the 
ebullition, replacing the water evaporated during the process until 
a portion of the filtered liquid is not precipitated on the addition of 
solution of ferric chloride. When reaction is completed, filter the 
liquid and wash the hydrate of chromium, unite the liquids, and 
concentrate to crystallization. If the evaporated liquid possess an 
acid reaction, the addition of caustic potash, in sufficient quantity to 
cause a weak alkaline reaction, will greatly facilitate the subsequent 
crystallization. 

6(K 4 FeCy 6 ) + K 2 O 2 7 + 8HC1 = 3(K 6 Fe 2 Cy 12 ) 
+ 8KC1 + H 2 + Cr 2 6HO. 

Test. — To a portion of the solution add solution of ferrous 
sulphate ; a precipitate falls. This precipitate is ferricyanide 
of iron (Turnbull's blue), Fe" 3 Fe'" 2 Cy' 12 , or Fe H 3 Fdcy VI . 

K 6 Fdcy + 3FeS0 4 = Fe 3 Fdcy + 3K 2 S0 4 . 

It will be noticed that the change in the condition of the iron 
keeps up the balance of the atomic values of the various parts of 
the radicals or of the salts ; the quantivalential equilibrium is 
maintained. 

A solution of 1 part of ferricyanide of potassium in 20 of water 
constitutes the " Solution of Ferricyanide of Potassium," B. P. 

Hydrofluoric Acid (HF) and other Fluorides.— 
Molecular weight of HF, 20. The chief use of hydrofluoric 
acid is in the etching on glass. The operation, performed on 
the small scale, also constitutes the best test for fluorine, the 
elementary radical of all fluorides. 

Process and Test. — Warm any odd piece of window-glass, 
having an inch or two of surface, until a piece of beeswax 
rubbed on one side yields a thin oily film. W r hen cool make a 
cross, letter, or other mark on the glass by pressing a pointed 
piece of wood, a penknife, or file, through the wax. Place a 
few grains of powdered fluor spar, the commonest natural fluo- 
ride, in a porcelain crucible (or a lead cup), add a drop or two 
of sulphuric acid, cover the crucible with the prepared glass, 
waxed side downwards, and gently warm the bottom of the 
crucible in a fume-chamber or in the open air, in such a way 
as not to melt the wax. After a few minutes remove the 
glass, wash the waxed side by pouring water over it, scrape 
off most of the wax, then warm the glass, and wipe off the 
remainder ; the marks made through the wax will be found to 
be permanently etched on the glass ; the acid has eaten into or 
etched (from the German dtzen, to corrode) the glass. 



HYPOPHOSPHITES. 343. 

In the above operation the fluoride of calcium and sulphuric acid 
yield hydrofluoric acid, thus : — 

CaF 2 + H 2 80 4 = CaS0 4 + 2HF. 

The hydrofluoric acid gas and the silica of the glass then yield 
gaseous fluoride of silicon (SiFJ, which escapes, and water, thus : — ■ 

4HF + Si0 2 = 2H 2 + SiF 4 . 

The silica, being removed from the glass, leaves furrows or etched 
portions. 

Note. — In the experiment just described, the liberated hydrofluoric 
acid also attacks the siliceous glazing of the porcelain crucible ; so 
that in important cases, where search is made for very small quanti- 
ties of fluorine, vessels of platinum or lead must be employed. 

Uses. — The aqueous solution of hydrofluoric acid used by etchers, 
and commonly termed simply hydrofluoric acid, or " fluoric" acid, is 
prepared in leaden stills and receivers, and kept in leaden or gutta- 
percha bottles. Except these materials, as well as platinum and 
fluor spar, hydrofluoric acid rapidly attacks any substance of which 
bottles and basins are usually made. It quickly cauterizes the skin, 
producing a painful, slow-healing sore. A mixture of hydrofluoric 
acid and fluoride of ammonium, known as " white acid," is also used 
for etching glass. 

Quantivalence. — The atom of fluorine, like that of chlorine, bro- 
mine, or iodine, is univalent (F / ). The great analogy existing be- 
tween these radicals extends to their compounds. 

Fluorine is said to be a colorless gas ; but, from the avidity with 
which it combines with all elements (except oxygen), it is so difficult 
of isolation as hitherto to preclude satisfactory study of its physical 
properties. 

Hypophosphorous Acid (H 3 P0 2 , or HPH,0 2 ) and other 
Hypo-phosphites. — Boil together, in a fume-chamber, two or 
three grains of phosphorus, three or four grains of slaked lime, 
and about a quarter of an ounce of water until phosphoretted 
hydrogen, a spontaneously inflammable, badly-smelling gas, 
ceases to be evolved. The lime must not be in great excess or 
the hypophosphite will be converted into phosphate as fast as 
formed. The mixture, filtered, and excess of lime removed by 
carbonic acid gas, yields solution of hypophosphite of calcium 
(Ca2PH,0 2 ) (Calcii Hypophosphis, U. S. P.). The salt may be 
obtained in crystals by evaporating and slowly cooling. 

2P 4 + 6H 2 -f 3CaH 2 2 = 3(Ca2PH 2 2 ) + 2PH 3 . 

Phosphoretted Hydrogen (PH 8 ). — The above reaction is also that 
by which phosphoretted hydrogen, the third hydride of phosphorus. 
may be prepared. If the gas is to be collected, the phosphorus and 
water may lirst be boiled in a flask until a jet of spontaneously in- 



344 SALTS OF RARER ACIDULOUS RADICALS. 

flammable phosphorus vapor escapes, with steam, from the end of 
the attached delivery-tube. Strong solution of caustic potash or 
soda is next very gradually poured into the flask through a funnel 
tube previously fitted into the cork, the liquid being kept boiling. 
Phosphoretted hydrogen is then evolved, and, if the delivery-tube 
dip under water, may be collected, or allowed to slowly pass up 
through the water bubble by bubble, so as to form the peculiar rings 
of smoke (phosphoric anhydride) characteristic of the experiment. 

The Hypophosphite of Potassium (Potassii Hypophosphis, U. S. P.) 
(KPH 2 2 ) may be obtained in the same way from its hydrate, and 
many other hypophosphites (Mg2PH 2 2 ,6H 2 0, Fe2PH 2 2 ,6H 2 0, etc.) 
similarly from other hydrates, or by double decomposition of the 
calcium salt and carbonates. 

Hypophosphite of sodium (NaPH 2 2 ,H 2 0) (Sodii Hypophosphis, 
U. S. P.) may be made by decomposing solution of hypophosphite of 
calcium by carbonate of sodium, filtering, and evaporating to dryness. 
It is a white, granular, deliquescent substance. 

Ca2PH 2 2 + Na 2 C0 3 = 2NaPH 2 2 + CaC0 3 . 

When heated, the water is first evolved, then hydrogen and spon- 
taneously inflammable phosphoretted hydrogen, and a mixture of 
pvrophosphate and metaphosphate of sodium remains (Rammels- 
berg). 

5NaPH 2 2 = NaJ> 2 0, + NaP0 3 + 2PH 3 + 2H 2 . 

Hypophosphorous acid, the hydrogen hypophosphite, may be pre- 
pared by decomposing the barium salt with sulphuric acid or the 
calcium salt by oxalic acid ; hypophosphite of quinine by dissolving 
the alkaloid in hypophosphorous acid, or by decomposing sulphate 
of quinine by hypophosphite of barium. The latter is obtained on 
boiling excess of pure hydrate of barium with hypophosphite of am- 
monium until all ammonia is evolved. The ammonium salt is formed 
on bringing calcium hypophosphite and oxalate of ammonium to- 
gether in presence of a little ammonia. Hypophosphite of Iron 
(Fe 2 6PH 2 2 ) (Ferri Hrjjjophosphis, U. S. P.) may be obtained by 
dissolving ferric hydrate in cold aqueous hypophosphorous acid and 
evaporating the solution. 

The hypophosphites are often used in medicine in the form of 
syrups (Syrupus Hypophosphitum, U. S. P., and Syr. ffypophosphitum 
cum Ferro, U. S. P.). The term hypophosphite is in allusion to the 
smaller amount (virb, hupo, under or deficiency) of oxygen in these 
compounds (R/ 3 P0 2 ) than in the phosphites (R 3 P0 3 ), a class of salts 
having again less oxygen in their molecules than exists in those of 
the phosphates (R 3 Pb 4 ). The prefix hypo has similar significance 
in such words as hyposulphite and hypochlorite. 

Tests. — To a portion of the above solution of hypophosphite 
• of calcium add solution of chloride of barium, chloride of cal- 
cium, or acetate of lead ; in neither case is a precipitate ob- 
tained, whereas soluble phosphates and phosphites yield white 



HYPOSULPHITES. 345 

precipitates of phosphate or phosphite of barium, calcium, or 
lead. To other portions add solutions of nitrate of silver and 
mercuric chloride ; the respective metals are precipitated as by 
phosphites. To another small portion add zinc and dilute sul- 
phuric acid; hydrogen and phosphoretted hydrogen are evolved 
as from phosphites. To another portion add sufficient oxalic 
acid to remove the calcium ; filter ; to the solution of hypo- 
phosphorus acid add solution of sulphate of copper, and slowly 
warm the mixture ; solid brown cuprous hydride (Cu 2 H 2 ) is 
precipitated : increase the heat to the boiling-point ; hydrogen 
is evolved and metallic copper set free. Add the ordinary nitric 
solution of a molybdate or tungstate to a hypophosphite solu- 
tion, and then a very little sulphurous acid ; a blue precipitate 
results, or, in very dilute solutions, a blue color, deepened on 
shaking or gently warming. Heat a small quantity of a solid 
hypophosphite on the end of a spatula in a flame ; it splits up 
into pyrophosphate, a little metaphosphate, hydrogen, phos- 
phoretted hydrogen, and, sometimes, water, burning with a 
phosphorescent light — the official hypophosphite of calcium 
yielding about 80 per cent, of residue. 

7(Ca2PH 2 2 ) = 3Ca 2 P 2 7 + Ca2P0 3 + 6PH 3 + H 2 + 4H 2 

Five grains of hypophosphite of calcium, if of good quality, 
will almost decolorize a solution of twelve grains of perman- 
ganate -of potassium on boiling the mixture for about ten 
minutes. Five grains of hypophosphite of sodium should 
almost decolorize eleven and a half grains of permanganate 
under similar conditions. The same effect follows the addition 
of the permaganate to an acid solution of a phosphite, but not 
to that of an ortho-, meta-, or pyrophosphate. 

Hyposulphurous Acid (H 2 S 2 3 ) and other Hyposul- 
phites. — The only hyposulphite of much interest in pharmacy 
is the sodium salt (Sodii Hyposulphis, U. S. P.) (Na 2 S 2 3 , 511,0). 
Hyposulphites are now commonly termed thiosulpkates (e. g. } 
H 2 S0 3 S; Na 2 S0 3 S), being regarded as sulphates (e. g. Na.,SO,) 
in whose molecules one atom of oxygen is displaced by one of 
thelon (Oe~iov, sulphur). 

Process. — Heat together gently, or set aside in a warm place, 
a mixture of solution of sulphite of sodium (Na 2 S0 8 ) and a 
little powdered sulphur ; combination slowly takes place, and 
hyposulphite of sodium is formed. The solution, filtered from 
excess of sulphur, readily yields crystals. (The solution of 
sulphite of sodium may be made by saturating a solution of 
• soda with sulphurous acid gas.) 



346 SALTS OF RARER ACIDULOUS RADICALS. 

Use of Hyposulphite of Sodium in Quantitative Analysis. — 
In the British Pharmacopoeia hyposulphite of sodium is given 
as a reagent for the quantitative estimation of free iodine in 
volumetric analysis. To a few drops of iodine-water add cold 
mucilage of starch ; a deep-blue color (starch iodide) is pro- 
duced. To the product add solution of hyposulphite of sodium 
until the blue color just disappears. This absorption of iodine 
is sufficiently definite and delicate to admit of application for 
quantitative purposes. It depends on the combination of the 
iodine with half of the sodium in two molecules of the hypo- 
sulphite, the hyposulphurous radicals of the two molecules 
apparently coalescing to form a new radical, the tetrathionic 
(from rirpaq, tetras, four, and Oeiov, theion, sulphur), tetrathio- 
nate of sodium (Na 2 S 4 6 ) and iodide of sodium being formed. 

Sulphur Oxyacids. — It will be as well here to give the formulae of 
other oxyacids of sulphur, forming with the four already mentioned 
a series that is as useful as the series of compounds of nitrogen and 
oxygen in illustrating the soundness of Daltous atomic theory. The 
first named (H 2 S0 2 ) is now generally, in chemistry, termed hypo- 
sulphurous acid, and the fourth (H 2 S 2 3 ) thiosulphuric acid. More- 
over, there appears to be an acid (H 2 S 2 4 ) between those having the 
formulas H 2 S 2 3 and H 2 S 2 6 , which Bernthsen says is Schtitzen- 
berger's hydrosulphurous acid, but which the latter chemist says is 
probably a distinct acid. 

? H 2 S 2 4 

Dithionic Acid H 2 S 2 6 

Trithionic Acid .... H 2 S 3 6 
Tetrathionic Acid . . . H 2 S 4 6 
Pentathionic Acid . . . H 2 S 5 6 



Hydrosulphurous Acid . . H 2 S0 2 
Sulphurous Acid .... H 2 S0 3 

Sulphuric Acid H 2 S0 4 

Hyposulphurous or | tt q n 
Thiosulphuric Acid j " u ^ u » 



Use of " Hypo " in Photography. — The sodium hyposulphite 
is largely used in photography to dissolve chloride, bromide, or 
iodide of silver off plates which have been exposed in the 
camera. Prepare a little chloride of silver by adding a chloride . 
(chloride of sodium) to a few drops of solution of nitrate of 
silver. Collect the precipitated chloride on a filter, wash, and 
add a few drops of solution of hyposulphite of sodium ; the 
silver salt is dissolved, solution of double hyposulphite of so- 
dium and silver being formed. The solution of this double hy- 
posulphite has a remarkably sweet taste, sweeter than syrup, 
if the solution is strong. The double hyposulphite of sodium 
and gold is employed for giving a pleasant tint to photographic 
prints. 

Test. — To solution of a hyposulphite add a few drops of 
dilute sulphuric or other acid ; hyposulphurous acid is set free, 
but at once begins to decompose into sulphurous acid, recog« 



LACTATES. 347 

nized by its odor, and free sulphur (2H 2 S 2 3 = 2H 2 S0 3 + S 2 ). 
This reaction constitutes the best test for hyposulphites. An- 
other test of a soluble simple hyposulphite is its power of dis- 
solving chloride of silver with production of a more or less 
sweet solution. 



QUESTIONS AND EXERCISES. 

588. Give the formula of ferrocyanide of potassium. 

589. What is the supposed constitution of ferrocyanide of potas- 
sium? 

590. Enumerate the tests for ferrocyanogen. 

591. What are the respective reactions of ferrocyanide of potas- 
sium with strong and weak sulphuric acid ? 

592. Mention and explain a common source of carbonic oxide in 
households. What is the product of its combustion ? 

593. Write equations or diagrams illustrative of the changes 
effected on ferrocyanide of potassium during its conversion into fer- 
ricyanide. 

594. By what reactions may the presence of a ferricyanide in a 
solution be demonstrated ? 

595. State the difference between Prussian blue and Turnbull's 
blue. 

596. Describe the source, mode of preparation, chief use of, and 
test for hydrofluoric acid. 

597. Illustrate by a diagram the preparation and composition of 
hyposulphite of sodium. 

598. Mention the uses and characteristic reactions of hyposulphite 
of sodium. 

599. Give the names and formulae of eight acids, each containing 
hydrogen, sulphur and oxygen. 



Lactic Acid (HC 3 H 5 3 ) and other Lactates. — Lactic acid 
occurs naturally in willow-bark (Dott). When milk turns sour its 
sugar has become converted into an acid appropriately termed lactic 
(lac, lactis). Other saccharine and amylaceous substances also by 
fermentation yield lactic acid. The hydrogen lactate (lactic acid) 
is official (Acidum Lacticum, U. S. P.). 

Process. — Lactate of calcium and lactic acid may be pro- 
pared as follows: Mix together eight parts of sugar, one of 
common cheese, three of chalk, and fifty of water, and sot 
aside in a warm place (about 80° F.) for two or three weeks ; 
a mass of small crystals of lactate of calcium results. Remove 
these, rccrystallizc from hot water, decompose by sulphuric acid, 
avoiding excess, digest in alcohol, filter off the sulphate of calcium, 
evaporate the clear solution to a syrup; this residue is lactic 
acid; when of sp. gr. 1.212 it contains 75 per cent, oi' real acid. 



348 SALTS OF RARER ACIDULOUS RADICALS. 

Lactate of Iron (Ferri Lactas, U. S. P. ; Fe2C3H 5 3 ,3H 2 0) 
may be made by digesting iron filings in warm diluted lactic 
acid (1 acid to 16 water) till effervescence of hydrogen ceases, 
filtering and setting aside to cool and crystallize. The crystals 
are collected, washed with alcohol, and dried. This ferrous 
lactate occurs in greenish-white crystalline, crusts or grains, of 
a mild, sweetish, ferruginous taste, soluble in forty-eight parts 
of cold and twelve of boiling water, but insoluble in alcohol. 
Exposed to heat, it froths up, gives out thick, white, acid 
fumes, and becomes black, sesquioxide of iron being left. If 
it be boiled for fifteen minutes with nitric acid of the specific 
gravity 1.20, a white, granular deposit of mucic acid will oc- 
cur on the cooling of the liquid. 

Tests. — No single reaction of lactic acid is sufficiently dis- 
tinctive to form a test. The crystalline form of the lactate of 
calcium, as seen by the microscope, is characteristic. The 
production of this salt, and the isolation of the syrupy acid 
itself, are the only means, short of quantitative analysis, on 
which reliance can be placed. It is soluble in water, alcohol, 
and ether, but almost insoluble in chloroform. It is only 
slightly colored by cold sulphuric acid ; warmed with perman- 
ganate of potassium, it gives the odor of aldehyde. 

A variety of lactic acid has been obtained from the juice of 
fish ; it is termed sarcolactic acid (from aap~ : <rapy.ds, sarx, sarcos, 
flesh). Unlike lactic acid, it is precipitated by solution of sul- 
phate of copper. 

Malic Acid (C 4 H 6 5 ) and other Malates (from malum, 
an apple). — The juice of unripe apples, gooseberries, currants, 
rhubarb-stalks, strawberries, grapes, etc. contains malic acid and 
malate of potassium. When isolated it occurs in deliquescent 
prismatic crystals. 

Tests. — Malate of calcium (CaC 4 H 4 5 ) is soluble in water; 
hence the aqueous solution of malic acid or other malate is not 
precipitated by lime-water or chloride of calcium ; but on add- 
ing spirit of wine a white precipitate falls, owing to the insolu- 
bility of the calcium malate in alcohol. Malates are precipi- 
tated by lead-salts ; on warming the malate of lead with acetic 
acid it dissolves, separating out in acicular crystals on cooling. 
If the mixture be heated without acid, the malate of lead 
agglutinates and fuses. 

Hot strong sulphuric acid chars malic acid far less readily than it 
does nearly all other organic acids. 

Asparagin (C 4 H 8 N 2 3 ,H 2 0). — This proximate principle of plants 
occurs in many vegetable juices, and doubtless plays a very import- 
ant part in their nutrition. It is deposited in crystals when the fresh 
juices of asparagus, marshmallow, etc. are rapidly evaporated. It 



MALATES. 349 

is noticed here because malic acid is readily obtained from it by oxi- 
dation, nitrogen being eliminated, and because its exact natural posi- 
tion among chemical substances is not yet well made out. The atoms 
of its molecule are those of aspartate of ammonium (NH 4 C 4 H 6 N0 4 ), 
into which it is converted when its solution is long boiled. Decom- 
posed by aid of ferments, asparagin, absorbing hydrogen, yields 
succinate of ammonium (NH 4 ) 2 C 4 H 4 4 . Such reactions as these and 
the formation of the lactic acid of willow-bark from sugars may 
suggest to the student possible modes in which chemical changes 
take place in the plant-department of the vast laboratory of nature. 

Meconic Acid (H 2 C 7 H 2 7 ,3H 2 0). — Opium contains meconic 
acid (from p.7}xcov, mekon, a poppy) partially combined with 
morphine. To concentrated infusion of opium nearly neutral- 
ized by ammonia add solution of chloride of calcium ; meconate 
of calcium is precipitated. Wash the precipitate, place it in a 
small quantity of hot water, and add a little hydrochloric acid; 
the clear liquid (filtered, if necessary) deposits scales of meconic 
acid on cooling (Acidum Meconicum, B. P.) 

Tests. — To solution of meconic acid or other meconate, or 
to infusion of opium, add a neutral solution of ferric chloride ; 
a red solution of meconate of iron is produced. To a portion 
of the mixture add solution of corrosive sublimate ; the color 
is not destroyed ; to another portion add hydrochloric acid ; 
the color is discharged. (These reagents act on sulphocyanate 
of iron, which is of similar tint, in exactly the opposite man- 
ner.) To another portion add a drop of a dilute acid and boil ; 
the color is not discharged. (A solution of ferric acetate, 
which is of similar color, is decomposed on boiling, giving a 
colorless fluid and a red precipitate of ferric oxyacetate.) 

The normal meconates of potassium, sodium, and ammonium are 
soluble in water, the acid meconates very slightly soluble, the meco- 
nates of barium, calcium, lead, copper, and silver insoluble in water, 
but soluble in acetic acid. ■ 

Metaphosphoric Acid (HP0 3 ) and other Metaphos- 
phates. — Prepare phosphoric anhydride (P 2 5 ) by burning a 
small piece of phosphorus in a porcelain crucible placed on a 
plate and covered by an inverted test-glass tumbler, half-pint 
measure-glass, or some such vessel. After waiting a few 
minutes for the phosphoric anhydride to fall, pour a little 
water on the plate and filter the liquid; the product is solution 
of metaphosphoric acid (from fisrd, meta, a preposition de- 
noting change). 

PA + H 2 = 2HPO ; , 

Tests. — To solution of metaphosphoric acid add ammonio- 
nitrate of silver, or to a neutral metaphosphate add solution 



350 SALTS OF RARER ACIDULOUS RADICALS. 

of nitrate of silver ; a white precipitate (AgP0 3 ) is obtained. 
This reaction sufficiently distinguishes metaphosphates from 
the ordinary phosphates or orthophosphates (from opduz. orthos. 
straight), as the common phosphates may, for distinction, be 
termed (which give, it will be remembered, a ydloic precipitate 
with nitrate of silver). Another variety of phosphates shortly 
to be considered, the pyrophosphates, also gives a white precipi- 
tate with nitrate of silver. To the solution of metaphosphoric 
acid obtained as above, or by the action of acetic acid on a 
metaphosphate, add an aqueous solution of white of egg ; 
coagulation of the albumen ensues. Xeither orthophosphoric 
nor pyrophosphoric acid coagulates albumen. When mixed 
with an equal volume of Tincture of Chloride of Iron, meta- 
and pyrophosphoric acids give a precipitate after some time 
(U. S. P.). Boil the aqueous solution of metaphosphoric acid 
for some time ; on testing the solution the acid will be found 
to have been converted into orthophosphoric acid : — 

HP0 3 + H 2 = HaPOi (orthophosphoric acid). 

The ordinary medicinal phosphoric acid is made from phos- 
phorus and nitric acid, the liquid being evaporated to a syrupy 
consistence to remove the last traces of nitric acid. It may 
contain pyrophosphoric and metaphosphoric acids, if the heat 
employed be high enough to remove the elements of water : — 

2H 3 PO, — H 2 = HJP 9 7 (pvrophosphoric acid). 
H 3 P0 4 - H 2 = HPO3 (metaphosphoric acid). 

On redilution the metaphosphoric acid only slowly reabsorbs 
water. If, therefore, on testing, metaphosphoric be found to be 
present, the solution should be boiled until conversion to ortho- 
phosphoric acid has occurred. 

Xitrous Acid (HX0 2 ) and other Xitrites. — Strongly 
heat a fragment of nitrate of potassium or of sodium on a 
piece of platinum foil ; oxygen is evolved and nitrite of potas- 
sium remains. 

Test. — Dissolve the residue in water, add a few drops of 
dilute sulphuric acid, then a little weak solution of iodide of 
potassium, and. lastly, some mucilage of starch ; the deep-blue 
compound of iodine and starch is at once produced. Repeat 
this experiment, using nitrate of potassium instead of nitrite; 
no blue color is produced. 

2HI - 2HNO, = 2H 2 + 2X0 - I 2 . 

Teste for Nitrites in Wafer. — This liberation of iodine by nitrites 
and not by nitrates is a reaction of considerable value in searching 






NITRITES. 351 

for nitrites in ordinary drinking-waters, the occurrence of such salts 
being held to indicate the presence of nitrogenous organic matter in 
a state of oxidation or decay. The sulphuric acid used in the opera- 
tion must be pure, and the iodide of potassium free from iodate. If 
much organic matter is present, however, the nitric acid liberated by 
the sulphuric may be reduced to nitrous acid. It is perhaps best, 
therefore, to add acetic acid, and (Fresenius) distil over 10 or 20 per 
cent, of the water and apply the test to this distillate. Very dilute 
solutions of nitrous acid may thus be distilled without the slightest 
decomposition. 

Commercial Nitrous Acid. — The liquid commonly termed in phar- 
macy " nitrous acid " is simply nitric acid impure from the presence 
of nitrous acid. 

The chief nitrites used in medicine are nitrites of organic basylous 
radicals ; nitrite of ethyl (C 2 H 5 N0 2 ), or nitrous ether, is the most im- 
portant constituent of "sweet spirit of nitre' 1 ' 1 (Spiritus JEtheris 
Nitrosi, U. S. P. ; vide Index). Nitrite of amyl (C 5 H 11 N0 2 ) is also 
official {Amyl Nitris, U. S. P.) The double nitrite of cobalt and 
potassium is said to possess some therapeutic advantages over other 
nitrites. Nitrite of ammonium, on being heated, yields pure ni- 
trogen gas, NH 4 N0 2 = 2H 2 + N 2 . 

Ophelic Acid (C 13 H 20 O 10 ). — This is one of the principles to which 
the herb Ophelia chirata, or Chiretta (Chirata, U. S. P.), owes its 
bitterness. It is an amorphous yellow body. Another is Chiratin 
(C 26 H 48 15 ), decomposable by hydrochloric acid into Chiratogenin 
(C 13 H 24 3 ) and ophelic acid (Hbhn). 

Phosphorous Acid (H 3 P0 3 , or II 2 PI10 3 ). — It is necessary to notice 
this compound in order that the reader may have brought before him 
the three acids of phosphorus, namely, phosphoric acid (H 3 P0 4 ), 
phosphorous acid (H 2 PH0 3 ), and hypophosphorous acid (HPH 2 2 ) : 
it will be noticed that in composition they differ from each other 
simply in the proportion of oxygen, the molecules containing four, 
three, and two atoms respectively. In constitution they differ by 
the hypothetical phosphoric radical or grouping being trivalent, the 
phosphorous bivalent, and the hypophosphorous radical univalent. 
These three acids and corresponding salts must not be confounded 
with pyrophosphoric and metaphosphoric acids and salts ; the 
former are acids of phosphorus ; the latter, varieties of phosphoric 
acid ; the former, in composition, differ from each other in the pro- 
portion of oxygen they contain ; the latter, by the elements of 
water : — 

Acids of Phosphorus. Varieties of Phosphoric Acid. 

II,P0 4 phosphoric acid. H 8 P0 4 (ortho)phosphoric aeid. 

1I 2 PI10 3 phosphorous acid. H 4 P 2 7 pyrophosphoric aeid. 

]IPII 2 2 hyphosphorous acid. HP0 3 metaphosphoric aeid. 

When hypophosphorous acid is exposed to the air, oxygen is absorbed 
and phosphorous acid results ; by prolonged exposure more oxygen 
is absorbed and phosphoric acid is obtained. When phosphoric acid, 
or rather, for distinction, orthophosphoric aeid, is heated, every two 
molecules yield the elements and a molecule of water, and pyro- 




352 SALTS OF RAKER ACIDULOUS RADICALS. 

phosphoric acid results ; by prolonged exposure to heat more water 
is evolved, and metaphosphoric acid is obtained. These differences 
will be further evident if the formulae be written empirically, nearly 
all being doubled, thus : — 

H 6 P 2 4 hypophosphorous acid. 
H 6 P 2 6 phosphorous acid. 
npA f phosphoric acid, or 

6 2 8 { orthophosphoric acid. 
H 4 P 2 7 pyrophosphoric acid. 
H 2 P 2 6 metaphosphoric acid. 

phosphoric acid 
H 6 P 2 8 
phosphorous acid /\ pyrophosphoric acid^ 
H 6 PA _ / \ H 4 P 2 7 

hypophosphorous acid/ \ metaphosphoric acid 

H 6 PA 7 \ H 2 P 2 6 

From the central compound, phosphoric acid, the acids of phosphorus 
differ by regularly diminishing proportions of the element oxygen 
(see previous page), the varieties of phosphoric acid by regularly 
diminishing proportions of the elements of water. 

Prepare phosphorous acid by exposing a moist stick of phos- 
phorus to the air; a thin stream of heavy white vapor falls, 
which contains the acid in question. The best method of col- 
lection is to place the stick in an old test-tube having a hole in 
the bottom, to support this tube by a funnel or otherwise, the 
neck of the funnel being supported in a bottle, test-glass, or 
tube, at the bottom of which is a little water. Having collected 
some phosphorous acid in this way, apply the various tests 
already alluded to under Hypophosphorous Acid, first carefully 
neutralizing the phosphorous acid by an alkali. The means by 
which the varieties of phosphoric acid are distinguished have 
been given under Metaphosphoric Acid. Associated with the 
phosphorous acid, prepared as above stated, there is said to be 
an acid having the formula H 2 P0 3 , and termed hypophosphoric 
acid. Its anhydride would be P 2 4 . 

Other soluble phosphites are prepared by neutralizing phos- 
phorous acid with alkalies, and the insoluble phosphites by 
double decomposition. 

It is interesting to note that during the oxidation of phos- 
phorus in moist air, not only are phosphoric, hypophosphoric, 
and phosphorous acids formed, but also oxygen (0 2 ), ozone 
(0 3 ), peroxide of hydrogen (H 2 2 ), and a small quantity of 
nitrate of ammonium (NH 4 N0 3 ). 

Pyrogallic Acid. — See Tannic Acid. 



PYROPHOSPHATES. 353 

Pyrophosphoric Acid (H 4 P 2 7 ) and other Pyrophos- 
phates. — Heat ordinary phosphate of sodium (Na 2 HP0 4 ,- 
12H 2 0) in a crucible ; water of crystallization is first evolved 
and dry phosphate (Na 2 HP0 4 ) remains. Continue the heat to 
redness ; two molecules of the salt yield one molecule of water, 
and a salt having new properties is obtained : — 

2Na 2 HP0 4 - H 2 = Na 4 P 2 7 . 

It is termed pyrophosphate of sodium, in allusion to its origin 
(jrvp, pur, fire). From its solution in water it may be obtained in 
prismatic crystals (Na 4 P 2 O 7 ,10H 2 O), Sodii Pyrophosphas, U. S. P. 
Phosphoric acid itself is similarly affected by heat, 2H 3 P0 4 — H 2 
= H 4 P 2 7 (pyrophosphoric acid), though metaphosphoric acid is also 
formed. Other pyrophosphates are produced in a similar way, or by 
double decomposition and precipitation, or by neutralizing pyro- 
phosphoric acid by an oxide, hydrate, or carbonate. Possibly the 
pyrophosphates are only compounds of orthophosphates with meta- 
phosphates : — 

Na 4 P 2 7 = Na 3 P0 4 ,NaP0 3 . 

Tests. — To solution of a pyrophosphate add solution of nitrate 
of silver ; white pyrophosphate of silver (Ag 4 P 2 7 ) falls as a 
dense white powder, differing much in appearance from the 
white gelatinous metaphosphate of silver or the yellow ortho- 
phosphate. To pyrophosphoric acid, or to a pyrophosphate 
mixed with acetic acid, add an aqueous solution of albumen 
(white of egg) ; no precipitate occurs. Metaphosphoric acid, it 
will be remembered, gives a white precipitate with albumen. 



QUESTIONS AND EXERCISES. 

600. "What are the sources of lactic acid ? 

601. How is lactic acid usually prepared ? 

602. Name some of the plants in which malic acid is found. 

603. Whence is meconic acid derived ? 

604. By what process may meconic acid be isolated? 

605. Which is the best test for the meconic radical ? 

606. Distinguish meconates from sulphocyanates. 

607. Give the mode of manufacture of hyphophosphites. 

608. How is phosphoretted hydrogen prepared ? 

609. By what ready method may metaphosphoric acid be obtained 
for experimental purposes ? 

610. Name the tests for metaphosphates. 

611. How may meta- or pyrophosphoric acid be converted into 
orthophosphoric acid ? 

612. Describe the preparation of phosphorous acid. 

'613. State the relations which the acids of phosphorus bear to 
each other. 



354 SALTS OF RARER ACIDULOUS RADICALS. 

614. How are pyrophosphates prepared? 

615. Offer two views of the constitution of pyrophosphates. 

616. Define by formulae, metaphosphates, pyrophosphates, ortho- 
phosphates, phosphites, and hypophosphites. 

617. Mention the tests by which meta-, pyro-, and orthophosphates 
are analytically distinguished. 

618. Name the reactions by which hypophosphites and phosphites 
are detected. 

Silicic Acid (H 4 Si0 4 ) and other Silicates. — Silicates of various 
kinds are among the commonest of minerals. The various clays 
are aluminium silicates 5 the volcanic substance termed pumice- 
stone is a porous silicate of aluminium and of alkali-metals or alka- 
line-earth metals ; meerschaum is an acid silicate of magnesium 5 the 
ordinary sandstones are chiefly silica; sand, flint, quartz, agate, 
chalcedony, and opal are silicic anhydride or silica (Si0 2 ). Tripoli, 
a polishing powder now found in many other countries than Tripoli, 
consists of infusorial skeletons of nearly pure silica. Bath brick, 
used in knife-polishing, is a silico-calcareous deposit found in the 
estuary at Bridgwater and other places. Asbestos or amianth is a 
fibrous silicate of calcium and magnesium, the length of the fibres 
being from less than one inch to five feet. A single silk-like fibre can 
easily be fused, but, even in very small masses, and for all practical 
purposes, asbestos is infusible and, of course, incombustible. It is 
also a bad conductor of heat. It is already largely used in piston- 
rods and joints and for steam apparatus generally ; as a covering 
for boilers to prevent loss of heat by radiation ; and for so lining 
ceilings, floors, and other partitions as to render rooms, etc. fire- 
proof. Artificial silicates are familiar under the forms of glass and 
earthenware. Common English window-glass is usually silicate of 
calcium, sodium, and aluminium ; French glass, silicate of calcium 
and sodium ; Bohemian, chiefly silicate of potassium and calcium ; 
English flint- or crystal-glass for ornamental, table, and optical pur- 
poses is mainly silicate of potassium and lead. Earthenware is 
mostly silicate of aluminum (clay), with more or less of silicate of 
calcium, sodium, and potassium, and, in the commoner forms, sili- 
cates of iron. The various kinds of porcelain (China, Sevres, Meis- 
sen, Berlin, English), Wedgwood-ware, and stoneware are varieties of 
earthenware. Kaolin or China Clay, which is disintegrated felspar, 
not more common in China than in Devonshire and Cornwall, is the 
clay which yields the finest translucent porcelain. Crucibles, bricks, 
and tiles are clay silicates. Mortar is essentially silicate of calcium. 
Portland, Roman, and other hydraulic cements are silicates of cal- 
cium with more or less silicate of aluminium. 

Mix together a few grains of powdered flint or sand with 
about five or six times its weight of carbonate of sodium and 
an equal quantity of carbonate of potassium, and fuse a little 
of the mixture on platinum-foil in the blowpipe-flame ; the 
product is a kind of soluble glass. Boil the foil in water for 



SILICATES. 355 

a few minutes, filter ; to a portion add excess of hydrochloric 
acid, evaporate the solution to dryness, and again boil the resi- 
due in water and acid ; oxide of silicon, silicic anhydride, or 
silica (Si0 2 ), remains as a light, flaky, insoluble powder. 

The soluble glass or glass liquor of trade commonly contains 10 
or 12 per cent, of soda (NaHO) to 20 or 25 per cent, of silica (Si0 2 ). 
When of sp. gr. 1.300 to 1.400 it satisfies official requirements 
{Liquor Sodii Silicatis, U. S. P.). 

The foregoing operation constitutes the test for silicates. By 
fusion with alkali the silicate is decomposed, and a soluble alkaline 
silicate formed. On addition of acid, silicic acid (H 4 Si0 4 ) is set free, 
but remains in solution if sufficient water is present. The heat sub- 
sequently applied eliminates water and reduces the silicic acid to 
silica (Si0 2 ), which is insoluble in water or acid. By the addition 
of hydrochloric acid to soluble glass, and removal of the resulting 
alkaline chloride and excess of hydrochloric acid by dialysis (a pro- 
cess to be subsequently described), a pure aqueous solution of silicic 
acid may be obtained •, it readily changes into a gelatinous mass of 
silicic acid. Possibly some of the natural crystallized varieties of 
silica may have been obtained from the silica contained in such an 
aqueous solution, nearly all waters yielding a small quantity of 
silica when treated as above described. 

A variety of silicic acid (H 2 Si0 3 ) sometimes termed dibasic, to 
distinguish it from the normal or tetrabasic acid (H 4 Si0 4 ), results 
when the aqueous solution of the latter is evaporated in vacuo. 

Siliciuretted hydrogen, or hydride of silicon (Sili 4 ), is a sponta- 
neously inflammable gas formed on treating silicide of magnesium 
with hydrochloric acid. It is the analogue of light carburetted 
hydrogen or methane (CH 4 ). A liquid chloride of silicon (SiCl 4 ) 
analogous to tetrachloride of carbon (CC1 4 ) and a gaseous fluoride 
(SiF 4 ) also exist. Many other analogies are traceable between the 
elements silicon, boron, and carbon, especially amongst organic 
compounds (see p. 332). 

Succinic Acid (H 2 C 4 H 4 4 ). — Amber (Succinum) is a peculiar resin 
usually occurring in association with coal and lignite. From the fact 
that fragments of coniferous fruit are frequently found in amber, and 
impressions of bark on its surface, it is considered to have been an 
exudation from a species of Pinus now probably extinct. Heated in 
a retort, amber yields, first, a sour aqueous liquid containing acetic 
acid and another characteristic body appropriately termed succinic 
acid; second, a volatile liquid known as oil of amber (Oleum Suc- 
cini, U. S. P.), resembling the oil yielded by most resinous sub- 
stances under similar circumstances ; and, third, a pitchy residue 
allied to asphalt. The succinic acid is a normal constituent of the 
amber-, the acetic acid is produced during distillation. Succinic acid 
has also been found in wormwood, in several pine-resins, and in cer- 
tain animal fluids, such as those of hydatid cysts, and hydrocele. 
It may be obtained artificially from butyric, stearic, or margaric acid 
by oxygen. Tartaric, malic, and succinic acids arc also convertible 
the one into the other. 



356 SALTS OF RARER ACIDULOUS RADICALS. 

The succinates are normal (R/^H^OJ and acid (R / HC 4 H 4 4 ) ; 
a double succinate of potassium and hydrogen (KHC 4 H 4 4 ,H 2 C 4 H 4 4 ,- 
H 2 0), analogous to the superacid oxalate, salt of sorrel, also exists. 

Soluble succinates give a bulky brown precipitate with neu- 
tral ferric chloride, only less voluminous than ferric benzoate ; 
a white precipitate with acetate of lead, soluble in excess of 
either reagent ; with nitrate of silver, a white precipitate after 
a time ; with chloride of barium, no precipitate at first, but a 
white one of succinate of barium on the addition of ammonia 
and alcohol. Succinates are distinguished from benzoates by 
the last-named reaction, and by not yielding a precipitate on 
the addition of acids (vide p. 336). 

Sulphocyaxic Acid (HCyS) and other Sulphocyan- 
ates. — Boil together sulphur and solution of cyanide of potas- 
sium ; solution of sulphocyanate of potassium (KCyS) is formed. 
Warm the liquid, add hydrochloric acid till it faintly reddens 
litmus-paper, and filter ; any sulphide of potassium is thus de- 
composed, and the solutions may then be used for the follow- 
ing reactions. 

Tests. — Filter, and to a small portion of the solution add a 
ferric salt (Fe 2 Cl 6 ) ; a deep blood-red solution of ferric sulpho- 
cyanate is formed. To a portion of the red liquid add a little 
hydrochloric acid ; the color is not discharged (meconate of 
iron, a salt of similar tint, is decomposed by hydrochloric acid). 
In the acid liquid place a fragment or two of zinc ; sulphuretted 
hydrogen is evolved, and the red color disappears. To another 
portion of the ferric sulphocyanate add solution of corrosive 
sublimate ; the color is at once discharged. (Ferric meconate 
is unaffected by corrosive sublimate.) The ferric is the best 
test of the presence of a sulphocyanate ; indirectly, it is a good 
test of the presence of hydrocyanic acid or cyanogen. Solutions 
of pure ferrous salts are not colored by the solution of sulpho- 
cyanate. Red ferric acetate is decomposed by ebullition. 

Neither the ferric acetate nor the meconate yields its color 
to ether ; but on shaking ferric sulphocyanate solutions with 
ether the latter takes up the salt and becomes of a purple color. 

To solution of a sulphocyanate add solution of mercuric 
nitrate ; mercuric sulphocyanate is precipitated as a white 
powder. 

Pharaoh's Serpents. — Mercuric sulphocyanate, thoroughly washed 
and made up into little cones, forms the toy called Pharaoh's Ser- 

f>ent. It readily burns when ignited, the chief product being a 
ight solid matter (mellon, C 9 X 13 , and the melam, C 3 II 6 X 6 ), which 
issues from the cone in a snake-like coil of extraordinary length. 
The other products are mercuric sulphide (of which part remains in 



TANNATES. 357 

the snake and part is volatilized), nitrogen, sulphurous, and car- 
bonic acid gases, and vapor of metallic mercury. (For details con- 
cerning the economical manufacture of sulphocyanates, see Phar- 
maceutical Journal, second series, vol. vii. p. 581 and p. 152.) 

The sulphocyanic radical (CyS) is often termed sulphocyanogen 
(Scy), and its compounds regarded as sulphocyanides. Saliva con- 
tains sulphocyanates. 

Tannic Acid, or Tannin (Acidum Tannicum, IT. S. P., C M H 10 O 9> 
chiefly). — This is a common astringent constituent of plants, but is 
contained in largest quantity in galls (excrescences on the oak 
formed by the puncture and deposited ova of an insect). English 
galls contain from 14 to 28 per cent, of tannic acid ; Aleppo galls 
(Galla, U. S. P.) from 25 to 65 per cent. It is present also in the 
White Oak (Quercus Alba, U. S. P.). 

Process. — " Expose powdered galls (about an ounce is suffi- 
cient for the purpose of study) to a damp atmosphere for two 
or three days, and afterward add sufficient ether to form a soft 
paste. Let this stand in a well-closed vessel for twenty-four 
hours ; then, having quickly enveloped it in a linen cloth, sub- 
mit it to strong pressure so as to separate the liquid portion, 
which contains the bulk of the tannin in solution. Reduce the 
pressed cake to powder, mix it with sufficient ether, to which 
one-sixteenth of its bulk of water has been added, to form 
again a soft paste, and press this as before. Mix the expressed 
liquids, and expose the mixture to spontaneous evaporation 
until, by the aid subsequently of a little heat, it has acquired 
the consistence of a soft extract ; then place it on earthen 
plates or dishes and dry it in a hot-air chamber at a tempera- 
ture not exceeding 212°." 

The resulting tannic acid occurs in pale yellow vesicular 
masses or thin glistening scales, with a strongly astringent 
taste and an acid reaction, readily soluble in water and recti- 
fied spirit, very sparingly soluble in pure ether, though soluble 
in the ethereal fluid used in the foregoing process — a fluid 
which is really a mixture of true ether, water, and alcohol 
(both the latter contained in the common " ether "), and a little 
added water also. 

Medicinal Uses. — Tannic acid is very soluble in water, and in this 
form is usually administered in medicine. 

Tests. — To an aqueous solution of tannic acid add aqueous 
solution of gelatine ; a yellowish-white floeculent compound of 
the two substances is precipitated. This is a good test of the 
presence of tannic acid. 

Tanning. — The above reaction also serves to explain the chemical 
principle involved in tanning — the operation of converting skin into 



358 SALTS OF RARER ACIDULOUS RADICALS. 

leather. In that process the skin is soaked in infusion of oak-bark 
{Quercus cortex), the tannic acid of which, uniting with the gelati- 
nous tissues of the skin, yields a compound very well represented by 
the above precipitate. The outer bark of the oak contains little or 
no tannic acid, and is commonly shaved off from the pieces of bark 
which are large enough to handle ; useless coloring-matter is thus 
also rejected. Other infusions and extracts besides that of oak-bark 
(chiefly catechu, sumach, and valonia) are largely used by tanners : 
if used alone these act too quickly, and give a harsh, hard, less- 
durable leather. The tannic acid of these preparations is probably 
slightly different from that of oak-bark. 

To an aqueous solution of tannic acid add a neutral solution 
of a ferric salt ; dark bluish-black tannate of iron is slowly 
precipitated. This is an excellent test for the presence of tan- 
nic acid in vegetable infusions. The precipitate is the basis of 
nearly all black writing-inks. Ferrous salts give at first only 
a slight reaction with, tannic acid ; but the liquid gradually 
darkens. Characters written with this liquid become quite 
black in a few hours, and are very permanent. 

To an aqueous solution of tannic acid add solution of tartar- 
emetic ; tannate of antimony is precipitated. This reaction and 
that with gelatin are useful in the quantitative estimation of 
the amount of tannic acid in various substances, the separa- 
tion of the tannate of gelatin being much promoted by pre- 
viously adding some heavy neutral powder, such as sulphate 
of barium, and well stirring while pouring in the gelatin 
solution. 

Tannic acid as it occurs in oak-bark is said to be a glucoside, that 
is, like several other substances, yields glucose (grape-sugar) when 
boiled with dilute sulphuric or hydrochloric acid, the other product 
being gallic acid. 

Catechu, Gambier, or Terra Japonica, an extract of the Uncaria 
Gambier ; as Avell as the true Catechu, Cutch, or Terra Japonica, an 
extract from the Acacia catechu {Catechu, U. S. P. ; Catechu nigrum; 
P. I.) and A. Suma ; East Indian Kino (Kino, U. S. P.) from the 
Pterocarpus marsupium ; also Bengal or Butea Kino, from the Palas 
or Dhak tree, Butea frondosa (Butece gummi vel Kino Bengalensis, 
P. I.) ; and some other vegetable products, contain a variety of tannic 
acid [mimotannic acid), which gives a greenish precipitate with 
neutral solutions of ferric salts. According to Paul and Kingzett, it 
yields, when decomposed, unfermentable sugar, and an acid different 
from ordinary gallic acid. Catechu and Gambier also contain 
catechuic acid or catechin, C 13 H 12 5 , a body occurring in minute 
colorless acicular crystals, and, like mimotannic acid, affording a 
green precipitate with ferric salts. 

Bael fruit (Belos Fructus,- B. P.), from the jEgle Marmelos, is 
said to OAve its power as a remedy for dysentery and diarrhoea to a 
variety of tannic acid, but this is questionable. About 10 per cent. 



TAKNATES. 359 

of tannic acid is contained in the leaves of Castanea vesca {Castanea, 
U. S. P.), the tree yielding the common edible Spanish chestnuts. 
The rind of the fruit of the pomegranate (Punica granatum) 
(Granati Cortex, P. I.) contains tannic acid. The astringency 
of Pomegranate-root Bark (Granatum, U. S. P.) is due to a tannic 
acid (its anthelmintic properties probably to a resinoid matter, 
or possibly to what Tanret states to be a liquid alkaloid, pelli- 
tierine, C 16 H 30 N 2 O 2 ). A tannic acid also probably gives the 
astringency to Logwood (Hcematoxylon, U. S. P.). Rhatany- 
root bark (Krameria, U. S. P.) contains about 20 per cent, of 
tannic acid, its active astringent principle ; rhubarb-root, about 9 
per cent. Bearberry-\e&ves ( Uva Ursi, U. S. P.) owe most of their 
therapeutic power to about 35 per cent, of tannic acid. (The cause 
of their influence on the kidneys is not yet traced.) They also con- 
tain arbutin, a crystalline glucoside. Larch-bark (Laricis Cortex. 
B. P.), the inner bark of Pinus larix or Larix europoza, contains, 
according to Stenhouse, a considerable amount of a tannic acid 
giving olive-green precipitates with salts of iron, and larixin and 
larixinic acid (C 10 H 10 O5), a somewhat bitter substance. Areca nuts 
or Betel nuts (Areca, B. P.), from the Areca Palm (Areca catechu), 
besides the alkaloid arekane (Bombelon), contain a very active alka- 
loid, arecoline, C 8 H 13 N0 2 (Jahns), said to be the vermifugal prin- 
ciple, and, according to Fluckiger and Hanbury, about 15 per cent, 
of " tannic matter." The extract of the fruit of Gab, or Diospyros 
embryopteris (Diospyri Fructus, P. I.), is a powerful astringent con- 
taining tannic acid. The rhizome (Geranium, U. S. P.) of Geranium, 
maculatum, Spotted Cranesbill or Arum-root, contains both tannic 
and gallic acids. Sumac or Shumac, or Sumach, the leaves and 
stalks of^ various species of Rhus, chiefly Rhus coriaria, contains 
ordinary tannic acid and gallic acid. The fruit of sumach (Rhus 
glabra, U. S. P.) contains tannic and much malic acid. The bark of 
Prinos verticillatus, the Black Alder or Winterberry (Prinos, U. S. P.), 
contains tannin and a bitter principle. The principal constituent of 
the bark of the root of Rubus villosus, or high blackberry, and of R. 
canadensis and R. trivialis (Rubus, U. S. P.), is tannic acid. 

Gallic Acid (H 3 C T H 3 5 ,H 2 0) (Acidum Gallicum, U. S. P.) 
occurs in. small quantity in oak-galls and other vegetable sub- 
stances, but is always prepared from tannic acid. Powdered 
galls are moistened with water and set aside in a warm place 
for five or six weeks, or until a little treated with water and 
filtered yields a solution which is only slightly precipitated 
with solution of isinglass, occasionally being remoistened ; fer- 
mentation occurs, and impure gallic acid is formed. The prod- 
uct is treated with about three times its weight of water, 
boiled to dissolve the gallic acid, filtered, the solution set aside 
to cool, deposited gallic acid collected, drained, pressed between 
folds of paper to remove all mother-liquor, and, if necessary, 
purified by rccrystallization from water, or by solution in hot 
water with animal charcoal, which absorbs coloring-matter. 



360 SALTS OF RARER ACIDULOUS RADICALS. 

On filtering and cooling, most of the acid separates in the form 
of fawn-colored, slender acicular crystals. G-allic acid is soluble 
in 118 times its weight of cold or 3 of boiling water, freely in 
spirit, sparingly in ether, also in glycerin. 

The nature of the action by which gallic acid is thus produced is 
probably similar to that of the action of dilute acids on tannic acid. 
During the process oxygen is absorbed and carbonic acid gas evolved, 
the sugar being thus broken up or perhaps prevented from being 
formed. 

Test. — To an aqueous solution of gallic acid add a neutral 
solution of ferric salt ; a bluish-black precipitate of gallate of 
iron falls, similar in appearance to tannate of iron. Ferrous 
salts are also blackened by gallic acid. To more of the solu- 
tion add an aqueous solution of gelatin ; no precipitate occurs. 
By the latter test gallic acid is distinguished from tannic acid. 

Pyrogallic Acid or Pyrogallol (C 6 H 6 3 ). — This substance sublimes 
in light feathery crystals when gallic acid is heated. Or it may be 
formed by heating gallic acid with 3 or 4 times its weight of glycerin 
to 190° or 200° C. for a short time until carbonic acid gas ceases to be 
evolved. Longer heating at a lower temperature is not equally effec- 
tive, and below 100° C. probably no pyrogallol is produced (Thorpe). 
To an aqueous solution add a neutral solution of a ferric salt, a red 
color is produced. To another portion add a ferrous salt 5 a deep- 
blue color results. 

Test for the Three Acids. — To three separate small quantities of 
milk of lime in test-tubes add, respectively, tannic, gallic, and pyro- 
gallic acids ; the first slowly turns brown, the second more rapidly, 
while the pyrogallic mixture at once assumes a beautiful purplish- 
red color, changing to brown. These reactions are highly charac- 
teristic. They are accompanied by absorption of oxygen from 
the air. 

Use of Pyrogallic Acid in Gas-analysis. — A mixture of pyrogallic 
acid and solution of potash absorbs oxygen with such rapidity and 
completeness that a strong solution of each, passed up successively 
by a pipette into a graduated tube containing air or other gas, forms 
an excellent means of estimating free oxygen. The value of this 
method may be roughly proved by pouring a small quantity of each 
solution into a phial, immediately and firmly closing its mouth with 
a cork, thoroughly shaking the mixture, and then removing the cork 
under water ; the water rushes in and occupies about one-fifth of the 
previous volume of air, indicating that the atmosphere contains one- 
fifth of its bulk of oxygen. The small amount of carbonic acid gas 
present in the air is also absorbed by the alkaline liquid ; in delicate 
experiments this should be removed by the alkali before the addition 
of pyrogallic acid. 

Toxicodendric Acid is the volatile, excessively acrid and poisonous 
principle of the Poison Oak or Poison Ivy, the fresh leaves of which 
are official {Rhus toxicodendron, U. S. P.), Maisch. 



URATES. 361 

Uric Acid (H 2 C 5 H 2 N 4 03) and other Urates. — Acidulate 
a few ounces of human urine with hydrochloric acid, and set 
aside for twenty-four hours ; a few minute crystals of uric acid 
will be found adhering to the sides and bottom of the vessel 
and floating on the surface of the liquid. 

Microscopical Test. — Remove some of the floating particles 
by a slip of glass, and examine by a powerful lens or micro- 
scope ; the chief portion will be found to be in yellowish semi- 
transparent crystals, more or less square, two of the sides of 
which are even, and two very jagged ; but other forms are 
common (see the lithographs in the section on Urinary Sedi- 
ments.) 

Chemical Test. — Collect more of the deposit, place in a watch- 
glass or small white evaporating-dish, remove adherent moisture 
by a piece of blotting- or filter-paper, add a drop or two of 
strong nitric acid, and evaporate to dryness ; the residue will 
be red. When the dish is cold add a drop of solution of am- 
monia ; a purplish-crimson color results. The color is deepened 
on the addition of a drop of solution of potash. 

Notes. — Uric acid (or lithic acid) and urates (or lithates) of sodium, 
potassium, calcium, and ammonium are common constituents of an- 
imal excretions. Human urine contains about one part of urate 
(usually urate of sodium) in 1000. When more than this is present 
the urate is often deposited as a sediment in the excreted urine, 
either at once or after standing a short time. Uric acid or other 
urate is also occasionally deposited before leaving the bladder, and, 
slowly accumulating there, forms a common variety of urinary cal- 
culus. -Some urates are not definitely crystalline ; but when 

treated with dilute nitric acid or a drop of solution of potash, and 
then a drop or two of acetic acid, jagged microscopic crystals of 
uric acid are usually formed. — All urates yield the crimson color 
when treated as above described. This color is due to a definite 
substance murexid (C 8 H 8 N 6 6 ) (from the murex } a shell-fish of 
similar tint) ; and the test is known as the murexid test. The 
formation of murexid is due to the action of ammonia on alloxan, 
(C 4 IT 2 N 2 4 ,4II 2 0) and other white crystalline products of the oxida- 
tion of uric acid by nitric acid. Murexid is a good dye ; it may be 
prepared from guano (the excrement of sea-fowl), which contains a 
large quantity of urate of ammonium. The excrement of the ser- 
pent is almost pure ammonium urate. 

Uric acid and the urates will be again alluded to in connection 
with the subject of morbid urine. 

Constitution of Uric Acid. — The physiological and pathological im- 
portance of uric acid has obtained for it great attention from chemists, 
a knowledge of its composition being rightly regarded as amongst 
the most prominent of chemical desiderata. For an excellent resume 
of what has been done in this direction up to 1884, students ol' or- 
31 



362 SALTS OF RARER ACIDULOUS RADICALS. 

game chemistry may consult the Pharmaceutical Journal of Nov. 
22, 1884. 

Valerianic Acid or Valeric Acid (HC 5 H 9 2 ) and 
other Valerianates. — In a test-tube place a few drops of 
amylic alcohol (fusel oil) with a little dilute sulphuric acid 
and a grain or two of red chromate of potassium, cork the tube, 
set aside for a few hours, and then heat the mixture ; valerianic 
acid, of characteristic valerian-like odor, is evolved. 

Valerianic acid occurs naturally in valerian-root in association 
with the essential oil from which it is derived {vide Index), but is 
usually prepared artificially, by the foregoing process, from amylic 
alcohol, to which it bears the same relation as acetic acid does to 
common alcohol : — 

C 2 H 5 HO + 2 = HC 2 H 3 2 + H 2 
C 5 H u HO + 2 = HC 5 H 9 2 + H 2 0. 

Valerianate of Sodium (NaC 5 H 9 2 ) is prepared from the va- 
lerianic acid and valerianate of amyl obtained on distilling the 
mixture of amylic alcohol (4 fl. oz.), sulphuric acid (6£ A. oz. 
with 10 of water), and red chromate of potassium (9 oz. in 70 
of water). The mixture should stand for several hours before 
heat is applied. 

2(K 2 Cr0 43 O0 3 ) + 8H 2 S0 4 = 2(K 2 S0 4 ,Cr 2 3S0 4 ) + 8H 2 + 30, 

Red chromate of Sulphuric Sulphate of potassium Water. Oxy 

potassium. acid. and chromium gen, 

(Chrome alum). 

C 5 H u HO + 2 = HC 5 H 9 2 + H 2 



2C 5 H„HO + 2 = C,II U C 5 H 9 2 + 2H 2 

Amylic Oxygen. Valerianate Water, 

alcohol. of amyl. 

The distillate (70 or 80 oz.) is saturated with soda, which not 
only yields valerianate of sodium with the free valerianic acid, but 
decomposes the valerianate of amyl produced at the same time, more 
valerianate of sodium being formed and some amylic alcohol set 
free, according to the following equations : — 

HC 5 H 9 2 + NallO = NaC 5 H 9 2 + H 2 

Valerianic Soda. Valerianate Water, 

acid. of sodium. 

C 5 H u C 5 H 9 2 +NaHO = NaC 5 H 9 2 + C 6 H u HO 

Valerianate Soda. Valerianate Amylic 

of amyl. of sodium. alcohol. 

From the solution of valerianate of sodium (which should be 
made neutral to test-paper by careful addition of soda solution) 
the solid white salt is obtained by evaporation to dryness and 
cautious fusion of the residue. The mass obtained on cooling 



VALERIANATES. 363 

should be broken up and kept in a well-closed bottle. It is 
entirely soluble in spirit. 

Other Valerianates, as valerianate of zinc (Zinci Valerian as, 
U. S. P.) and ferric valerianate (Ferri Valerianas, U. S. P. ; 
Fe 2 6C 5 H 9 2 ), may be made by double decomposition of vale- 
rianate of sodium with the sulphate or other salt of the metal 
the valerianate of which is desired, the new valerianate either 
precipitating or crystallizing out. A hot solution of sulphate 
of zinc (5f parts) and valerianate of sodium (5 parts) in water 
(40 parts) gives a crop of crystals of valerianate of zinc on 
cooling. 

Tests. — Heated with diluted sulphuric acid, valerianates of 
the metals give valerianic acid, which has a highly character- 
istic smell. Valerianate of sodium thus treated, and the result- 
ing oily acid liquid purified by agitation with sulphuric acid 
and distillation, furnishes valerianic acid. Dry ammonia gaa 
passed into valerianic acid gives white lamellar crystals of 
valerianate of ammonium (Ammonii Valerianas, U. S. P.). 

The amylic alcohol (C 5 H n HO) from which valerianates are pre- 
pared may contain the next lower homologue, butylic alcohol 
(C 4 H 9 HO). This, during oxidation, will be converted into buty- 
ric acid (HC 4 H 7 2 ), the next lower homologue of valerianic acid 
(HC 5 H 9 2 ), and hence the various valerianates be contaminated by 
some butyrates. These are detected by distillation with diluted sul- 
phuric acid and addition of solution of acetate of copper to the dis- 
tillate, which at once becomes turbid if butyric acid be present. In 
this reaction valerianic and butyric acids are produced by double 
decomposition of the valerianate and butyrate by the sulphuric acid, 
and distil over on the application of heat. On the addition of ace- 
tate of copper (Cu2C 2 H 3 2 ) butyrate of copper (Cu2C 4 H 7 2 ,H 2 0) is 
formed, and, being almost insoluble in water, is at once precipitated, 
or remains suspended, giving a bluish-white opalescent liquid. Va- 
lerianate of copper (Cu2C 5 ll 9 2 ) is also formed after some time, but 
is far more soluble than the butyrate, and only slowly collects in 
the form of greenish oily drops, Avhich gradually pass into green- 
ish-blue hydrous crystalline valerianate of copper (Larocque and 
Huralt). 

Vanillic Acid (HC 8 H 7 3 ) or Vanillin (C 8 H 8 3 ) or Methylpro- 
tocatechuic Aldehyde (C 7 H 5 CH 3 3 ), the body to which is duo the 
odor and flavor of Vanilla. — The white crystals commonly found on 
vanilla — the prepared unripe pods of Vanilla planifolia— previously 
termed vanillin, were found by Carles to be a weak acid. It occurs 
in vanilla to the extent of from 1J to 3 per cent. Vanillin has 
recently been prepared artificially by Tiemann and Haarmann from 
coniferin, a glucoside existing in the sapwood of pines. The body 
remaining after the removal of glucose from coniferin or, indeed, 
coniferin itself, by action of a mixture of red ohromate oi' potas- 



364 SALTS OF RARER ACIDULOUS RADICALS. 

sium and sulphuric acid, yields the vanillin. It also may be ob- 
tained by a series of reactions starting from that of carbonic acid 
on carbo'late of potassium ; also from the eugenol of oil of cloves. 
By action of hydrochloric acid, vanillin yields chloride of methyl 
and protocatechuic aldehyd. Such reactions will be better under- 
stood when the pupil has studied succeeding sections on what is 
commonly termed Organic Chemistry. Artificial vanillin is less 
stable than natural vanillin, perhaps because with the latter is asso- 
ciated a preservative resin. 



QUESTIONS AND EXERCISES. 

619. What is the constitution of nitrites? 

620. Mention a test for nitrites in potable waters. 

621. Which nitrite is official ? 

622. Give the names of some natural and artificial silicates. 

623. What is " soluble glass " ? 

624. Distinguish between silica and silicic acid. 

625. How are silicates detected ? 

626. What is the quantivalence of silicon? 

627. Mention the sources, formulae, and analytical reactions of 
succinates. 

628. State the mode of manufacture and tests of sulphocyanates. 

629. What proportion of tannic acid is contained in galls? 

630. Describe a process for the preparation of Tannic Acid? 

631. Explain the chemistry of " tanning/' 

632. Enumerate the tests of tannic acid. 

633. What is the assumed constitution of tannic acid? 

634. Mention official substances other than galls whose astrin- 
gency is due to tannic acid. 

635. How is gallic acid prepared ? 

636. By what reaction is gallic distinguished from tannic acid ? 

637. Mention the characteristic properties of pyrogallic acid. 

638. Explain the murexid test for uric acid. 

639. Describe the artificial preparation of valerianic acid and 
other valerianates, giving diagrams or equations. 

6-40. What is the formula of valerianic acid ? 

641. How are butyrates detected in presence of valerianates? 



DETECTION OF THE ACIDULOUS RADICALS OF 
SALTS SOLUBLE IN WATER. 

Analytical operations may now be resumed, the detection of acid- 
ulous radicals being practised for two or three days, and then full 
analyses made, both for basylous and acidulous radicals. To this 
end a few compounds of stated metals (potassium, sodium, or am- 
monium) should be placed in the hands of the practical student for 



DETECTION OF ACIDULOUS RADICALS. 365 

examination according to the following paragraphs and Tables. 
Mixtures in which both basylous and acidulous radicals may be 
sought should then be analyzed. 

In examining salts soluble in water, and concerning which no 
general information is obtainable, search must first be made for any 
basylous radicals by the appropriate methods {vide page 220 or 256). 
Certain metals having been thus detected, a little reflection on the 
character of their salts will at once indicate what acidulous radicals 
may be, and what cannot be, present. Thus, for instance, if the 
substance under examination is freely soluble in water, and lead is 
found, only the nitric and acetic radicals need be sought, none other 
of the lead salts than nitrate or acetate being freely soluble in 
water. Moreover, the salt is more likely to be acetate than nitrate 
of lead, for two reasons : the former is more soluble than the latter, 
and is by far the commoner salt of the two. Medical and phar- 
maceutical students have probably, in dispensing, already learned 
much concerning the solubility of salts, and whether a salt is rarely 
employed or in common use. And although but little dependence 
can be placed on the chances of a salt being present or absent 
according to its rarity, still the point may have its proper weight. 
If, in a mixture of salts, ammonium, potassium, and magnesium 
have been found associated with the sulphuric, nitric, and hydro- 
chloric radicals, and we are asked how we suppose these bodies may 
exist in the mixture, it is far more in accordance with common sense 
to suggest that sal-ammoniac, nitre, and Epsom salt were originally 
mixed together than to suppose any other possible combination. 
Such appeals to experience regarding the solubility or rarity of salts 
cannot be made by any one not previously acquainted, or insuf- 
ficiently -.acquainted, with the characters of salts : in such cases the 
relation of a salt to water and acids can be ascertained by referring 
to the following Table (p. 367) of the solubility or insolubility of 
about five hundred of the common or rarer salts met with in chem- 
ical operations. 

The opposite course to the above (namely, to ascertain what acid- 
ulous radicals are present in a mixture, and then to appeal to ex- 
perience to tell what basylous radicals may be and what cannot be 
present) is impracticable ; for acidulous radicals cannot be separated 
out, one after the other, from one and the same quantity of substance 
by a similar treatment to that already given for basylous radicals. 
Indeed, such a sifting of acidulous radicals could scarcely be accom- 
plished at all, or only by a vast deal of labor. The basylous radicals 
must, therefore, be first detected. 

Even when the basylous radicals have been found, the acidulous 
radicals which may be present must be sought for singly, the only 
additional aid which can be brought in being the action of sulphuric 
acid, a barium salt, a calcium salt, nitrate of silver, and ferric chlo- 
ride on separate small portions of the solution under examination, 
as detailed in the second of the following Tables. 

Practical Analysis. 

Commence the analysis of an aqueous solution of a salt or 
81* 



366 DETECTION OF ACIDULOUS RADICALS. 

salts, the basylous radicals in which are known, by writing out 
a list of the acidulous radicals which may be, or, if more con- 
venient, of those which cannot be, present. To this end consult 
the following Table (p. 367) of the solubility of salts in water. 
Look for the name of the metal of the salt in the vertical 
column ; the letters S and I indicate which salts are soluble 
and which insoluble in water, an asterisk attached to the S 
meaning that the salt is slightly soluble. The acidulous part 
of the name is given in the top line of the Table. All the 
names are in alphabetical order, for facility of reference. 

Some of the salts marked as insoluble in water are soluble in 
aqueous solutions of soluble salts, a few forming soluble double salts. 
To characterize salts as soluble, slightly soluble, or insoluble only 
roughly indicates their relation to water : on the one hand, very few 
salts are absolutely insoluble in water ; on the other, there is a limit 
to the solubility of every salt. 

If only one, two, or perhaps three, given acidulous radicals can 
be in the liquid, test directly for it or them according to the re- 
actions given in the previous pages. If several may be present, 
pour small portions of the solutions, rendered neutral if necessary 
by ammonia, into five test-tubes, and add, respectively sulphuric 
acid, nitrate or chloride of barium, chloride of calcium, nitrate 
of silver, and ferric chloride ; then consult the Table on page 364, 
in order to correctly interpret the .effects these reagents may have 
produced. 

REMARKS OX THE PRECEDING TABLE. 

The first point of value to be noticed in connection with this Table 
is one of a negative character ; namely, if either of the reagents 
gives no reaction, it is self-evident that the salts which it decomposes 
with production of a precipitate must be absent. Then, again, if the 
action of one of the reagents indicates the absence of certain acid- 
ulous radicals, those radicals cannot be precipitated by the other re- 
agents : thus, if the action of sulphuric acid points to the absence 
of sulphides, sulphites, carbonates, cyanides, and acetates, these salts 
may be struck out of the other lists, and the examination of subse- 
quent precipitates be so far simplified. Or, if the barium precipitate 
is soluble in hydrochloric acid and the calcium precipitate in acetic 
acid, neither sulphates nor oxalates can be present. Observing these 
and other points of difference, which will be seen on careful and 
thoughtful reflection, and remembering the facts suggested by a 
knowledge of what basylous radicals are present, one acidulous rad- 
ical after the other may be struck off as absent or present, leaving 
only one or two as the objects of special experiment, Among the 
chief difficulties to be encountered will be the separation from each 
other of chlorides, bromides, iodides, and cyanides, or of tartrates 
from citrates, and confirmatory tests of the presence of certain com- 



DETECTION OF ACIDULOUS RADICALS. 



367 



?$ | §-.8-8 g.g'H p.£^ 1§ go 2. 



^ 






COGOCOCGGOGOCO.<>GOGpCOGOCOCO.^>COGOGOGOGOGOGOCOGOGOCOGO 



I— (t— I l-H •<> CO l— I CD. h- IHHI- II- 



HMMMMI— IHh I -o ,M M M CD M 



HDDHK^HHH^HH^HHHH^H^^HHffit- 



SlBHai-CHHHHHH^H^HHHHI- 



GQGOGOCOrOMCOGCGOI-HGOCOCOGOGOGOGOCGGOGOGOGOCOGCGGGOGO 



rCM^^aQMCO-^COM-^HHCOCO^COCOCOCOCCCOCOCOCO-oCQCQ 



CDHHHOSHK^HHCDCQOOH^^aJOS^HiJD-oHHHGDH 



H5C>T5>o!KH!/2>*H->sa!H->5HHH^HHHCO-ai9i/l>oQC^ 



Cyanide. 



Hydrate. 



GO GO CO CO CO M CO CO CO M h-l CO CO CD l-l GO GO CO GO GO CO h-i CO w GO -. 



COCOGOCOCOCOGOCOGOCOGOGOCOCO-oCOGOGOGOCOCOGOGOCO-oGOCO 



HHHtjCCOHCC^HHHHHH^COCOHHCCHHHHCCCCH 



HDUHHiJOHCCHHHHHHHHHHHHHifiHHCCl- 



Oxide. 
Phosphate. 



COMGOCOGOCOGOCOGOGOCOGOGO)-i.^COCOCCGOCOi7pCOCOK-lMCOCO 



CO M M -e CO M CO CO CO .>s « CO GO M >o GQ •*> M Qg CD CD QO M M M CO M 



CDCOCD.^COMCD-^CDMMCOCOM-cCO(^COCDCOCOCO(-t(-it-tCOCD 



Sulphate. 
Sulphide. 
Sulphite.. 
Tartrate. 



368 



DETECTION OF ACIDULOUS RADICALS. 



1 o 



O g 

W ^ 
o p3 

H 

oT ^ 
w 2 

H ^ 

<J ~ 

H H 

M H 

* < 

„ p 

g.H 

2 w p 

^ S o 
° ^ g ' 

H O Sf 
§ « ^ 

O Q <J 
M .« 

W H ^ 3 

Q < § I 

3 w & » 

§ g «! 5 

CO p 

CO ~ h ' 

H H =o 

S S 5 

g S H -g 

Z m 8 § 

O co o 
H 5 .« 

SB** 

H Ph co 

R ^ w 

g P H 
g « < 

ft --P 



CO~ PM 

H co 
H O 

* H £ 

a «r 

O <} 

H £ 

O 

W pq 

n 





Nitrates. 
Chlorates. 
Apply spe- 
cial tests. 


<D 

CD S=U 


Borates, yellowish. 
Sulphides, black. 
Carbonates, reddish. 
Oxalates, yellow. 
Phosphates, yel.-white. 
Gives red color with 
acetates, if neutral. 


cd 

"S ® 


Chlorides, white. 

Bromides, white. 

Iodides, yellow. 

Cyanides, white. 

Borates, white. 

Sulphides, black. 

Sulphates, white. 

Carbonates, white. 

Oxalates, white. 

Tartrates, white. 

Phosphates, yellow. 

Citrates, white. 
Ofthese silver precipi- 
tates, the chloride, 
bromide, iodide, cya- 
nide, and sulphide 
are insoluble in di- 
lute nitric acid ; the 
rest soluble. 


| 

© P« 

CD CJ 

T3 CO 

■«■« »1 

Sh a. 


Borates. Oxalates. 

Sulphites. Tartrates. 

Sulphates. Phosphates. 

Carbonates. Citrates. 
Of these white calcium 
precipitates, the sul- 
phate only is sol. in 
much water; the bo- 
rate, carbonate, and 
citrate are sol. in solu- 
tion of chloride of am- 
monium: all are sol. 
in acetic acid except 
oxalate and some tar- 
trate and sulphate ; 
all are sol. in hydro- 
chloric acid, much 
sulphate excepted ; 
the dry tartrate and 
citrate char when 
heated; the sulphite 
and carbonate effer- 
vesce with acids. 


.2 

Si CO 

oj CD 

o ^ 


Borates. 

Sulphites. 

Sulphates. 

Carbonates.* 

Oxalates. 

Tartrates. 

Phosphates. 

Citrates. 
Of these white barium 
precipitates, the sul- 
phate is the only one 
insoluble in hydro- 
chloric acid ; the tar- 
trate and citrate char 
wheu heated on plat- 
inum foil ; the sul- 
phite and carbonate 
are decomposed with 
effervescence by acids. 


O DO 
<] CD 

.si 

•^ § 
■3-S 


Sulphides. 

Sulphites. 

Carbonates, 

with effervescence— 
hydrosulphuric and 
sulphurous acid gases, 
known by smell and 
carbonic acid gas, 
which has no special 
odor, being evolved. 

Cyanides, 

with production of 
the odor of hydro- 
cyanic acid. 

Acetates, 

with production of 
the odor of acetic acid 
when the solution is 
warmed. 



DETECTION OF ACIDULOUS RADICALS. 369 

pounds. These may all be surmounted on referring back to the 
reactions of the various radicals, as described under their hydrogen 
salts, the acids. 

In rendering a solution neutral for the application of the various 
group-tests, the employment of any large amount of acid or of alkali 
must be noted ; the presence of actual alkalies (that is, hydrates) or 
of acids themselves — free acids, so called — respectively, being thereby 
indicated. Free acids also betray themselves by the abundant effer- 
vescence which results on the addition of a carbonate. 

Sulphuric acid, the first group-test, may itself yield, especially 
when heated with some solid substances, sulphurous acid or hydro- 
sulphuric acid (see pp. 305 and 310); hence the production of the 
latter acids from a diluted solution only is evidence of the presence 
of a sulphide or sulphite. 

In the precipitate produced by chloride of barium, the second 
group-test, the oxalic radical may be specially sought by the test 
described in the "note" on p. 316. 

Chloride of calcium does not precipitate citrates readily or com- 
pletely in the cold ; therefore the mixture should be filtered and the 
filtrate boiled ; calcium citrate then falls. Calcium tartrate is soluble 
in solution of chloride of ammonium when quite freshly precipitated, 
but not after it has become crystalline. From their solution in 
chloride of ammonium, tartrate of calcium is mostly precipitated 
by ammonia, and citrate on boiling. 

The rarer acidulous radicals will very seldom be met with. Ben- 
zoates, hippurates (which give benzoic acid), hypochlorites, hyposul- 
phites, nitrites, and valerianates show themselves under the sulphuric 
treatment. Ferrocyanides, ferridcyanides, meconates, succinates, 
sulphocyUnates, tannates, and gallates appear among the salts whose 
presence is indicated by ferric chloride ; formiates, hypoplwsphites, 
malates, and others by nitrate of silver. Urates char when heated, 
giving an odor resembling that of burnt feathers. 

In actual practice the analyst nearly always has some clue to the 
nature of rarer substances placed in his hands. 

If chromium and arsenicum have been detected among the basy- 
lous radicals, those elements may be present in the form of chromates, 
arseniates, and arsenites, yielding with chloride of barium yellow 
chromato of barium and white arseniate and arsenite of barium, and 
with nitrate of silver, red chromate, brown arseniate, and yellow 
arsenite of silver. 



QUESTIONS AND EXERCISES. 

642. In analyzing an aqueous solution of salts, for which radicals 
would you first search, the basylous or the acidulous? and why? 

643. In an aqueous solution there have been found magnesium 
(Mg) and potassium (K), with the sulphuric radical (SOJand iodine 
(I); state the nature of the salts which were originally dissolved in 
the water, and mention the principles which guide you in the con- 
clusions. 



370 ANALYSIS OF SALTS. 

644. Give a sketch of the method by which to analyze a neutral 
or only faintly acid aqueous liquid for the acidulous radical of salts. 
In what stage of the process would the following salts be detected? 
a. Carbonates and Sulphates ; b. Oxalates ; c. Tartrates and Ni- 
trates ; d. Acetates and Sulphites ; e. Bromides and Cyanides 5 /. 
Borates; g. Iodides and Phosphates; h. Chlorates, Oxalates, and 
Acetates; i. Chlorides and Iodides;,;'. Sulphites; k. Sulphides, Car- 
bonates, and Nitrates ; I. Citrates and Sulphates. 

645. Nitrate of silver gives no precipitate in an aqueous solution ; 
what acidulous radicals may be present ? 

646. Chloride of barium gives no precipitate in a neutral solution, 
but nitrate of silver a white ; what acidulous radicals are indicated? 

647. Ferric chloride produces a deep-red color in a solution, chlo- 
ride of calcium yielding no precipitate ; what salts may be present ? 
and how may they be distinguished from each other? 

648. Ferric chloride gives a black precipitate in a solution in which 
sulphuric acid develops no odor ; to what is the effect due ? 



ANALYSIS OF SALTS. 
SINGLE OR MIXED, SOLUBLE OR INSOLUBLE. 

Thus far, all material substances, especially those of pharmaceutical 
interest, have been regarded as being definite compounds, and as 
having certain well-defined parts, termed, for convenience, basylous 
and acidulous respectively ; moreover, attention has been designedly 
restricted to those definite compounds which are soluble in water. 
But there are many substances having no definite or known composi- 
tion ; and of those having definite composition there are many having 
no definite or ascertained parts. Again, of those having definite 
composition, and whose constitution admits of the entertainment of 
theory, there are many insoluble in water. 

Chemical substances of whose composition or constitution little or 
nothing is at present known, are chiefly of animal and vegetable 
origin, and figure in tables of analysis under the convenient collec- 
tive title of " extractive matter ;'* they are not of immediate import- 
ance, and may be omitted from consideration. 

Of substances which are definite in composition, but whose parts 
or radicals, if they have any, are unknown or imperfectly known, 
there are only a few (such as the alkaloids, amylaceous and saccha- 
rine matters, the glucosides, alcoholic bodies, albumenoid. fatty, 
resinoid, and colorific substances) which have any considerable 
amount of medical or pharmaceutical interest ; these will be noticed 
subsequently. 

Definite compounds most frequently present themselves ; and of 
these by far the larger proportion (namely, the salts soluble in water) 
have already been fully studied. There remain, however, many salts 
which are insoluble in water, but which must be brought into a state 
of solution before they can be effectively examined from any analyt- 



PRELIMINARY EXAMINATIONS. 371 

ical, pharmaceutical, or physiological point of view. The next 
subject of laboratory work is, therefore, the analysis of substances 
which may or may not be soluble in water. This will involve no 
other analytical schemes than those which have been given, will in 
only one or two cases increase the difficulty of the analysis of the 
precipitate produced by a group-reagent, but will give roundness, 
completeness, and a practical bearing to the reader's analytical know- 
ledge. Such a procedure will at the same time bring into notice the 
methods by which substances insoluble in water are manipulated for 
pharmaceutical purposes, or made available for use as food by plants, 
or as food and medicine by man and animals generally. 

Preliminary Examination of Solid {chiefly Mineral) Salts. 

Before attempting to dissolve a salt for analysis, its appearance 
and other physical properties should be noted, and the influence of 
heat and strong sulphuric acid be ascertained. If the operator knows 
how to interpret what is thus observed, and to what extent to place 
confidence in the observations, he may more certainly obtain a high 
degree of precision in analysis, and will always gain some valuable 
negative information. But if he has only slight experience of the 
appearance and general properties of bodies, or has the habit of turn- 
ing what should be inferences from tentative processes into foregone 
conclusions, he should omit the preliminary examination altogether, 
or only follow it out under the guidance of a judicious tutor ; for it 
is impracticable here to do more than hint at the results which may 
be obtained by such an examination, or to so adapt description as to 
prevent a student from allowing unnecessary weight to preconceived 
ideas. 

Whatever be the course pursued, short memoranda describing re- 
sults should invariably be entered in the note-book. 

1. Examine the physicial characters of the salt in various 
ways, but never, or only rarely, by the palate, on account of 
the danger to be apprehended. 

If the salt is white, colored substances cannot be present; if 
colored, the tint may indicate the nature of the substance or of one 
of its constituents, supposing that the learner is already acquainted 
with the colors of salts. Closer observation, aided perhaps by a 
lens, may reveal the occurrence, in a pulverulent mixture, of small 
crystals or pieces of a single substance ; these should be picked out 
by a needle and examined separately. In a powder or roughly di- 
vided mixture of substances, the process of sifting (through such 
sieves as muslin of different degrees of fineness) often mechanically 
separates substances, and thus greatly facilitates analysis. The 
body may present an undoubted metallic appearance, in whirl) case 
only the metals existing under ordinary atmospheric conditions need 
be sought. Peculiarity in smell reveals the presence oi' ammonia. 
hydrocyanic, acid hydrcsulphum acid, stc. Between the fingers a 
substance is, perhaps, hard, soft, or gritty; consequent inferences 



372 GENERAL QUALITATIVE ANALYSIS. 

follow. Or the matter may be heavy, like the salts of barium or 
lead ; or light, like the carbonates and hydrates of magnesium 5 or 
may be one of the pharmaceutical^ well-known class of "scale" 
preparations. 

2. Place a grain or two of the salt in a small dry test-tube 
or in a piece of ordinary tubing, closed at one end, and heat it, 
at first gently, then more strongly, and finally, if necessary, by 
the blowpipe. 

Gases or vapors of characteristic appearance or odor may be 
evolved ; such as iodine, nitrous fumes, sulphurous, hydrocyanic, or 
ammoniacal gases. Much steam given by a dry substance indicates 
either hydrates or salts containing water of crystallization. (A 
small quantity of interstitial moisture often causes heated crystalline 
substances to decrepitate — from decrepo, I crackle — that is, break 
up with slight explosive violence, owing to the expansive force of 
the steam suddenly generated). A sublimate may be obtained, due 
to salts of mercury or arsenicum, to oxalic or benzoic acid, or to sul- 
phur free or as a sulphide — a salt wholly volatile containing such 
substances only. The compound may blacken, pointing to the pre- 
sence of organic matter — which, in common definite salts, will prob- 
ably be in the form of acetates, tartrates, and citrates, or as common 
salts of the alkaloids morphine, quinine, strychnine, or as starch, sugar, 
salicin, or in other definite or indefinite forms common in pharmacy 
and for which tests will be given in subsequent pages. If no char- 
ring occurs, the important fact that no organic matter is present is 
established. The residue may change color from presence or develop- 
ment of oxide of zinc, oxide of iron, etc., or melt from the presence 
of a fusible salt and absence of any large proportion of infusible 
salts, or, being unaltered, showing the absence of any large amount 
of such substances. 

3. Place a grain or two of the salt in a test-tube, add a drop 
or two of strong sulphuric acid, cautiously smelling any gas 
that may be evolved ; afterward slowly heat the mixture, 
noticing the effect, and stopping the experiment when any sul- 
phuric fumes begin to escape. 

Iodine, bromine, and nitrous or chlorinoid fumes will reveal them- 
selves by their color, indicating the presence of iodides, bromides, 
iodates, bromates, nitrates, and chlorates. The evolution of a color- 
less gas fuming on coming into contact with air, and having an irri- 
tating odor, points to chlorides, fluorides, or nitrates. Gaseous prod- 
ucts having a greenish color and odor of chlorine indicate chlorates, 
hypochlorites, or chlorides mixed with other substances. Slight 
sharp explosions betoken chlorates. Evolution of colorless gas may 
proceed from cyanides, acetates, sulphides, sulphites, carbonates, or 
oxalates. Charring will be due to citrates, tartrates, or other organic 
matter. If none of these effects are produced, most of the bodies 



PRELIMINARY EXAMINATIONS. 373 

are absent or only present in minute quantity. The substances 
apparently unaffected by the treatment are metallic oxides, borates, 
sulphates, and phosphates. 

4. Exposure of the substances to the blowpipe-flame, on plati- 
num wire, with or without a bead of borax or " microcosmic " salt* 
(phosphate of sodium, ammonium, and hydrogen, NaNH 4 HP0 4 ) 
— on platinum foil, in a porcelain crucible, or on a crucible-lid 
with or without carbonate of sodium — on charcoal, alone or in 
conjunction with carbonate of sodium, cyanide of potassium, 
or nitrate of cobalt, will sometimes yield important informa- 
tion, especially to one who has devoted much attention to re- 
actions produceable by the blowpipe-flame. The medical or 
pharmaceutical student, however, will seldom have time to work 
out this subject to an extent sufficient to make it a trustworthy 
guide in analysis. (See Plattner and Muspratt On the Use 
of the Blowpipe, and a chapter in Galloway's Manual of 
Quantitative Analysis. 

Methods of Dissolving and Analyzing Single or Mixed Solid Suit- 
stances. 

Having submitted the substance to preliminary examination, pro- 
ceed to dissolve and analyze by the following methods. These ope- 
rations consist in treating a well-powdered substance consecutively 
with cold or hot water, hydrochloric acid, nitric acid, nitro-hydro- 
chloric acid, or fusion with alkaline carbonates and solution of the 
product in water and acid. Resulting liquids are analyzed in the 
manner already described, or by slightly modified processes as de- 
tailed in the following paragraphs. 

Solution in Water. — Boil about a grain of the salt presented 
for analysis in about a third of a test-tubeful of water. If it 
dissolves, prepare a solution of about 20 or 30 grains in half an 
ounce or more of water, and proceed with the analysis in the 
usual way, testing first for the basylous radical or radicals by 
the proper group reagents (HC1, H 2 S, NH 4 HS, (NH 4 ) a CO„ 
(NH,). 2 HP0 4 ),p. 220 or 225, and then for the acidulous radical 
or radicals, directly or by aid of the prescribed reagents 
(H 2 S0 4 , BaCl,, CaCl 2 , AgNO,, Fe 2 Cl 6 ), p. 366. 

If the salt is not wholly dissolved by the water, ascertain 
whether or not any has entered into solution, by filtering, if 
necessary, and evaporating a drop or two of the dear liquid to 
dryness on platinum foil ; the presence or absence of a residue 

* So called because formerly obtained from the urine of man, who was 
called the microcosmos or I idle world. 



374 GENERAL QUALITATIVE ANALYSIS. 

gives the information sought. If anything is dissolved, pre- 
pare a sufficient quantity of solution for analysis and proceed 
as usual, reserving the insoluble portion of the mixture, after 
thoroughly exhausting with water, for subsequent treatment 
by acids. 

Solution in Hydrochloric Acid. — If the salt is insoluble in 
water, digest about a grain of it (or of the insoluble portion 
of a mixed salt) in a few drops of hydrochloric acid, adding 
water, and boiling if necessary. If the salt wholly dissolves, 
prepare a sufficient quantity of the liquid, noticing whether or 
not any effervescence (due to the presence of sulphides, sul- 
phites, carbonates, or cyanides) occurs, and proceed with the 
analysis as before, except that the first step, the addition of 
hydrochloric acid, may be omitted. 

The analysis of this solution will in most respects be simpler than 
that of an aqueous ^solution, inasmuch as the majority of salts (all 
those soluble in water) will be absent. This acid solution will, in 
short, only contain : chlorides produced by the action of the hydro- 
chloric acid on sulphides, sulphites, carbonates, cyanides, oxides, 
and hydrates : and certain borates, oxalates, phosphates, tartrates, 
and citrates (possibly silicates and fluorides) which are insoluble in 
water, but soluble in acids without apparent decomposition. The first 
four — sulphides, sulphites, carbonates, and cyanides — will have re- 
vealed themselves hy the occurrence of effervescence during solution ; 
and the presence of oxides and hydrates may often be inferred by 
the absence of compatible acidulous radicals. The borates, oxalates, 
phosphates, tartrates, and citrates alluded to will be reprecipitated 
in the general analysis as soon as the acid of the solution is neutral- 
ized ; that is, will come down in their original state when ammonia 
and sulphydrate of ammonium are added to the usual course. Of 
these precipitates, only the oxalate of calcium and the phosphates 
of calcium and magnesium need occupy attention now 5 for oxalate 
and phosphate of barium seldom or never occur, and the borates, 
tartrates, and citrates met with in medicine or in general analysis 
are all soluble in water. These phosphates and oxalates, then, will 
be precipitated in the course of analysis along with iron, their pres- 
ence not interfering with the detection of any other metal. If, from 
the unusual light color of the ferric precipitate, phosphates and 
oxalates are suspected, it is treated according to the following 
Table (reference to which should be inserted in the Table for metals, 
under Fe, pp. 220 and 255). 



METHODS OF EFFECTING SOLUTIONS. 



375 



PRECIPITATE OF PHOSPHATES, OXALATES, AND FERRIC HYDRATE. 

Dissolve in HC1, add citric acid, then NH 4 HO, and filter. 



Filtrate 

Fe. 

Add HC1 and 

K 4 Fcy. 

Blue ppt. 



Precipitate 
Ca 3 2P0 4 , CaC 2 4 , Mg 3 2P0 4 . 
Boil in acetic acid and filter. 



Insoluble 

CaC 2 4 .* 

White. 

(CaF 2 may 

occur here.) 



Filtrate 
Ca 3 2P0 4 , Mg 3 2P0 4 . 

Add (NH 4 ) 2 C 2 4 , stir, filter. 



Precipitate 

white, including 

Ca 2 2P0 3 . 



Filtrate. 

Add NHJIO. 

White ppt. 

MgNH 4 P0 4 . 



In analyzing phosphates and oxalates advantage is also frequently 
taken of the facts that the phosphoric radical is wholly removed 
from solution of phosphates in acid by the addition of an alkaline 
acetate, ferric chloride, and subsequent ebullition, as described un- 
der "Phosphoric Acid" (p. 328), and that dry oxalates are converted 
into carbonates by heat, as mentioned under "Oxalic Acid" (p. 314). 
See also p. 328, 4th Analytical Reaction. 

Certain arseniates and arsenites, insoluble in water but soluble in 
hydrochloric acid, may accompany the above phosphates and oxa- 
lates if from any cause hydrosulphuric acid gas has not been pre- 
viously passed through the solution, or passed for an insufficient 
length of time. 

If the substance insoluble in water does not wholly dissolve 
in hydrochloric acid, ascertain if any has entered into solution, 
by filtering, if necessary, and evaporating a drop of the clear 
liquid to dryness on platinum foil ; the presence or absence of a 
residue gives the information sought. If anything is dissolved, 
prepare a sufficient quantity of solution for analysis, and proceed 
as usual, reserving the insoluble portion of the mixture, after 
thoroughly exhausting with hydrochloric acid and well washing 
with water, for the following treatment by nitric acid. 

Solution in Nitric Acid. — If the salt is insoluble in water 
and hydrochloric acid, boil it (or that part of it which is in- 
soluble in those menstrua) in a lew drops of nitric acid. If it 

* Oxalates after being healed effervesce on the addition o( acidj iluo- 
rides may be detected by the "etching test." 



376 GENERAL QUALITATIVE ANALYSIS. 

wholly dissolves, remove excess of acid by evaporation, dilute 
with water, and proceed with the analysis. 

This nitric solution can contain only very few substances ; for 
nearly all salts soluble in nitric acid are also soluble in hydrochloric 
acid, and therefore will have been removed previously. Some of the 
metals, however (Ag, Cu, Hg, Pb, Bi), as well as amalgams and 
alloys, unaffected or scarcely affected by hydrochloric acid, are read- 
ily attacked and dissolved by nitric acid. Many of the sulphides, 
also insoluble in hydrochloric acid, are dissolved by nitric acid, 
usually with separation of sulphur. Calomel is converted, by long 
boiling with nitric acid, into mercuric chloride and nitrate. The 
nitrates here produced are soluble in water. 

This nitric solution, as well as the hydrochloric and aqueous solu- 
tions, should be examined separately. Apparently time would be 
saved by mixing the three solutions together and making one analy- 
sis. But the object of the analyst is to separate every radical from 
every other ; and when this has been partially accomplished by sol- 
vents, it would be unwise to again mix and separate a second time. 
Moreover, solvents often do what the chemical reagents cannot — 
namely, separate salts from each other. This is important, inas- 
much as the end to be obtained in an analysis is not only an enu- 
meration of the radicals present, but a statement of the actual con- 
dition in which they are present; the analyst must, if possible, state 
of what salts a given mixture was originally formed — how the basy- 
lous and acidulous radicals were originally distributed. In attempt- 
ing this, much must be left to theoretical considerations; but a pro- 
cess by which the salts themselves are separated is of trustworthy 
practical assistance ; hence the chief advantage of analyzing sepa- 
rately the solutions resulting from the action of water and acids on 
a solid substance. 

Solution in Nitro- Hydrochloric Acid. — If the salt or any 
part of a mixture of salts is insoluble in water, hydrochloric 
acid, and nitric acid, digest it in nitro-hydrochloric acid, warm- 
ing or even boiling gently if necessary ; evaporate to remove 
excess of acid, dilute, and proceed as before. 

Sulphide of mercury and substances only slowly attacked by hy- 
drochloric or nitric acid, as, for example, calomel and ignited ferric 
oxide, are sufficiently altered by the free chlorine of aqua regia to 
become soluble. 

Analysis of Insoluble Substances. 

If the substance is insoluble in water and acids, it is one or 
more of the following substances : Sand and certain silicates, 
such as pipeclay and other clays ; fluor spar ; cryolite (3NaF,- 
A1F 3 ) ; sulphates of barium, strontium, and possibly calcium ; 
cinstone ; antimonic oxide ; glass ; felspar (double silicate of 
aluminium and other metals) ; chloride of silver; sulphate of 



ANALYSIS OF INSOLUBLE SUBSTANCES. 377 

lead. It may also be or contain carbon or carbonaceous mat- 
ter, in which case it is black and combustible, burning entirely 
or partially away when heated in the air ; or be or contain sul- 
phur, in which case sulphurous gas is evolved, detected by its 
odor, when the substance is heated in the air. A drop of so- 
lution of sulphydrate of ammonium added to a little of the 
powder, will at once indicate the presence or absence of salts 
of such metals as lead and silver. For the other substances 
proceed according to the following (Bloxam's) method : — 

Four or five grains of the dry substance are intimately mixed 
with twice the quantity of dry carbonate of sodium, and this 
mixture well rubbed in a mortar with five times its weight of 
deflagrating flux (1 of finely-powdered charcoal to 6 of nitre). 
The resulting powder is placed in a thin porcelain dish, or 
crucible, or clean iron tray, and a lighted match applied to the 
centre of the heap. Deflagration ensues, and decomposition of 
the various substances occurs, the acidulous radicals going to 
the alkali-metals to form salts soluble in water, the basylous 
radicals being simultaneously converted into carbonates or 
oxides. The mass is boiled in water for a few minutes, the 
mixture filtered, and the residue well washed. The filtrate 
may then be examined for acidulous radicals and aluminium, 
and the residue dissolved in dilute hydrochloric acid and ana- 
lyzed by the ordinary method. 

The only substance which resists this treatment is chrome-iron 
ore. 

To detect alkali in felspar, glass, or cryolite, Bloxam recommends 
deflagration of the powdered mineral with one part of sulphur and 
six of nitrate of barium. The mass is boiled in water, the mixture 
filtered, hydrate and carbonate of ammonium added to remove ba- 
rium, the mixture again filtered, and the filtrate evaporated and ex- 
amined for alkalies by the usual process. 

Hydrates and Oxides. 

If no acidulous radical can be detected in a substance under 
analytical examination, or if the amount found is obviously in- 
sufficient to saturate the quantity of basylous radical present, 
the occurrence of oxides or hydrates, or both, may be suspected. 
Confirmation of their presence will be found in the general 
rather than in any special behavior of the substances. Some 
hydrates yield water when heated — in a dry test-tube held 
nearly horizontally in a flame, so that moisture may condense 
on the cool part of the tube. Some oxides yield oxygen— de- 
tected by heating in a test-tube, and inserting the incandescent 
end of a strip of wood. Soluble hydrates cause abundant evo- 
32* 



378 GENERAL QUALITATIVE ANALYSIS. 

lution of ammonia gas when heated with solution of chloride 
of ammonium. Soluble hydrates also give characteristic pre- 
cipitates with the various metallic solutions. Hydrates and 
oxides insoluble in water not only neutralize much nitric acid 
or acetic acid, but are thereby converted into salts soluble in 
water. Most oxides and hydrates have a characteristic appear- 
ance. In short, some one or more properties of an oxide or a 
hydrate will generally betray its presence to the student who 
not only has knowledge respecting chemical substances, but 
has cultivated the faculties of observation and perception. 



QUESTIONS AND EXERCISES. 

649. Describe the preliminary treatment to which a salt may be 
subjected prior to systematic analysis. 

650. Mention substances which might be recognized by smell. 

651. Which classes of salts are heavy, and which light? 

652. Name some bodies detectable by their color. 

653. What inference may be drawn from the appearance of steam 
when dry substances are heated ? 

654. Why do certain crystals decrepitate? 

655. If a powder sublimes on being heated, to what classes of 
compounds may it belong? 

656. When heat causes charring, what conclusion is drawn? 

657. No change occurring by heat, which substances cannot be 
present ? 

658. Give example of salts which are identified by their reaction 
with strong sulphuric acid ; and by their comportment in the blow- 
pipe-flame, with or without borax or microcosmic salt. 

659. What are the solvents usually employed in endeavoring to 
obtain a substance in a state of solution, and what is the order of 
their application? 

660. Name a few salts which may be present in an aqueous solu- 
tion. 

661. Mention some common compounds insoluble in water, but 
soluble in hydrochloric acid. 

662. What substances are attacked only by nitric acid or nitro- 
hydrochloric acid? 

663. At what stage of analysis do arsenites and arseniates show 
themselves ? 

664. Sketch out a method for the complete analysis of a liquid 
suspected to be an aqueous solution of neutral salts. 

665. How can earthy phosphates and oxalates with ferric oxide 
be separated from each other? 

666. How would you proceed to analyze an alloy? 

667. Ity what process may substances insoluble in water or acids 
be analyzed ? 

668. How would you qualitatively analyze glass ? 



RECAPITULATORY AND OTHER NOTES. 379 

Recapitulatory and other T^otes on the Constitution of the 
Definite Chemical Compounds commonly termed Salts. 

The molecules of a salt contain radicals — which may be either 
elementary or compound : pp. 38 and 67. 

Each radical has a definite exchangeable value : p. 121. 

The definite exchangeable values of radicals differ in different 
series of radicals : p. 122. 

In one and the same molecule of a salt, two or more different 
atoms of the same element may possess the two distinct functions 
of being (a) a single definite distinct radical and (6) one member 
of a group of atoms which together form a single definite distinct 
radical : p. 262. 

The relation to each other, either of the elementary or the com- 
pound radicals in organic substances or salts, is apparently far more 
complex than the relation to each other of the elementary and com- 
pound radicals in inorganic or mineral salts. 

The properties of salts are regarded as depending on (a) the 
nature, (b) the number, and (c) the position in relation to each 
other of the elementary and compound radicals in a molecule. 

Dumas, afterwards Laurent, and then Gerhard, attempted the 
classification of salts under such types as the following : — 



1} 



h}° 



II J 

The hydrogen type. The water type. The ammonia type. 

Other chemists have extended the number of such types of salts. 
Further; by writing the typical formulae in the above and other man- 
ners a mode of indicating the facts assumed to be dependent on the 
position of the atoms in a molecule has been sought to be obtained. 
Finally, the natural development of this train of thought and of 
practice has produced the graphic formula; of Kekule, Frankland, 
and others. 

Caution. — The conjectural or theoretic character of our ideas re- 
specting masses of matter being formed of molecules, and molecules 
of atoms, and that molecules contain radicals consisting of one or 
more atoms, must never be lost sight of — highly valuable and prac- 
tically useful though the hypotheses be: pp. 38, 51, 262, 263, 285, 

Berthollefs Laics. — "When we cause two salts to react by means 
of a solvent, if, in the course of double decomposition, a new salt 
can be produced less soluble than those which we have mixed, this 
salt will be produced. When we apply dry heat to two salts, if, by 
double decomposition, a new salt can be produced more volatile than 
the salts previously mixed, this salt will be produced." 

MalaguWs Lair. — When solutions of two different salts are mixed, 
and metathesis occurs and four salts result, the proportions o[' the 
salts to each other are dependent on the strength or intensity of 
force with which the respective basylous and acidulous radical? are 
united. 



380 ADVICE TO STUDENTS. 

The state of equlibriuin just mentioned may be permanent or 
temporary. The latter condition obtains when one of the salts 
which may possibly be produced is insoluble, for as soon as pre- 
cipitation occurs the equilibrium is upset, and is re-established 
only to be upset again, and so on until from the four salts there 
result one in solution and one out of solution. This would seem to 
be the way in which the laws termed Berthollet's work. 

The Periodic Law. — An idea of Xewland's, elaborated by Men- 
delejeff and Lothar Meyer, points to a law thus expressed "by the 
latter chemist : "If the elements are arranged in order of increasing 
atomic weights, the properties of these elements vary from member 
to member of the series, but return more or less nearly to the same 
value at certain fixed points in the series ;" for example, Li, Be, B. C, 
N, 0, F, Xa. Mg, Al, Si, P, S, CI, K, Ca. etc. The periodicity of 
properties here alluded to occurs at about every eighth member of 
the series, irresistibly suggesting the periodicity of the musical scale. 
Thus sodium becomes the octave to litmus, silicon to carbon, phos- 
phorus to nitrogen, sulphur to oxygen, chlorine to fluorine, potas- 
sium to sodium, calcium to magnesium. Each chemical note (element) 
is distinct from the other, yet there is this curious harmon3 r between 
any one and the eighth on either side. There are gaps in some of 
the series suggesting elements yet to be discovered, and irregularities 
suggesting the desirability of reconsidering some of the present 
atomic weights : and other difficulties occur. Clearly, the properties 
of the elements are in some way dependent on their atomic weights, 
or. at all events, there is some common relationship between the 
elements. Evidently, there is less of fundamental difference between 
them than we assume when we regard them as distinct elements. 
They would seem to be not so distinct as we commonly imagine. 
Whence the observed relationship of lithium, sodium, and potassium, 
of X. P. As. Sb, and Bi. of 0, S, Se, and Te (p. 301), of C. B. and 
Si; of CI, Br, and 1 (p. 277)? Are the so-called elements one and 
the same matter, differing only in state? They have not yet been 
transmuted. The subject is not developed sufficiently to warrant 
further consideration in this Manual. Medical and pharmceutical 
students will '.find it fully considered in more advanced works. 
Papers and general statements will also be found in most journals 
of pharmacy. (See Pharmaceutical Journal, Ser. 3, vl. xviii. p. 882.) 



ADVICE TO STUDENTS 

Respecting the Method of Studying the following pages on 
Organic Chemistry, 

Both medical and pharmaceutical students of Organic Chemistry 
maybe divided into two classes — namely, junior students, or those 

who, in the first instance at all events, desire to obtain only a gen- 
eral acquaintance with the subject; and senior students, or those 
who. having some general information, desire more complete and 
thorough knowledge of this branch of the science. To the members 



ADVICE TO STUDENTS. 381 

of each of these classes who use this Manual some advice concerning 
the kind and extent of work they may hope to accomplish will per- 
haps be acceptable. 

Junior Students. — The whole of the following section on Organic 
Chemistry should be read through carefully once or twice, with the 
object not so much of remembering all that is stated, as of acquiring 
(a) a general view of the scope of the subject, (6) a clear notion of 
the modes of classifying organic substances, and (r) an intelligent 
perception of their broad relationships to one another, (d) Special 
attention should be given to the methods of preparing and testing the 
particular substances officially recognized in the British Pharma- 
copoeia, the student of practical chemistry preparing actual speci- 
mens of most of these substances, as well as going through tests for 
them and testing for impurities in them. He should make small 
quantities of chloroform, iodoform, spirit of nitrous ether, acetic 
ether, and a volatile oil ; should extract gum from a gum-resin, 
purify some benzine, test aloin, and examine methylated spirit for 
its methylic constituent ; prepare some spirit of wine by fermenta- 
tion, concentrating the product until it will burn ; make ether ; con- 
vert amylic alcohol into valerianic acid ; test carbonic acid and 
glycerin; manufacture a little soap; extract mannite from manna ; 
go through the analytical reactions of cane- and grape-sugar ; obtain 
starch from wheat flour, maize Hour, and a potato, and examine each 
product with the microscope ; make dextrin, pyroxylin, and collodion ; 
prepare and test aldehyde and try the action of lime on chloral hy- 
drate ; prepare and test acetic, oxalic, and citric acids ; emulsify 
sweet and bitter almonds ; prepare elaterin and test jalap-resin and 
salicin ^ extract morphine or quinine, or both, and perform the tests 
for the chief alkaloids of opium, cinchona, and nux vomica ; and test 
albumen and pepsin. Having gone through these operations, the 
junior student should again read through the whole section. 

/Senior students, having done all that junior students are in the 
previous paragraph advised to do, should thoughtfully study every 
page, reading what one other author, at least, has to say on each 
subject. More especially, they should actually prepare or test or 
otherwise experiment with one or more typical members of most of 
the series or sub-series of organic bodies. For example, they should 
prepare the hydrocarbon methane (from acetate of sodium), convert 
it into a haloid derivative (by one of the given methods), transform 
this into the alcohol (by the agency of oxide of silver and water), and 
this again into the acid (by oxidation). The preparation of acety- 
lene and ethylene and some of their derivatives should be tried ; the 
differences between turpentine and petroleum spirit be experiment- 
ally proved; nitro-benzene be made, this be converted into aniline, 
and this again into "mauve;" aloin should be prepared; methylic 
alcohol be extracted from crude wood-spirit and absolute alcohol be 
obtained from spirit of wine; alcohol and acetic acid be regenerated 
from the acetic ether previously prepared (by ebullition with a strong 
aqueous solution of potash); iodide or bromide of ethyl and perhaps 
zinc-ethyl be made; glycol be prepared and then be oxidized; glyce- 
rin be examined ; starch be converted into dextrin and into sugar : 



382 ADVICE TO STUDENTS. 

malt extract be examined for diastase ; trinitrocellulin be made ; 
acetic aldehyde be fully examined and aldehyde-ammonia be pre- 
pared ; lactic acid be made ; benzoic and salicylic acids and aldehy des 
be obtained ; natural urea be extracted and artificial urea be made ; 
the glucosides be examined ; and one or two artificial alkaloids be 
prepared, etc. Melting-points and boiling-points of pure substances 
should be taken ; and fractional distillation should be applied either 
to acetic acid with a view to separate glacial acid on the one hand 
from water or weak aqueous acid on the other, to mixed alcohol and 
water with the object of attempting their re-separation as far as pos- 
sible, or to some such mixture. Especially must the operations of 
quantitative analysis of organic compounds, in due time, be fully 
and thoroughly performed. 

Other Students. — Students who have no occasion to apportion their 
periods of study in the manner contemplated in the previous two 
paragraphs are recommended to go through the succeeding sections 
as they have gone through the foregoing — namely, page by page. 

Note. — Students will find that in working at organic chemistry, 
so called, they are not departing from the method of study hitherto 
pursued. Hitherto they have concentrated attention on the chief 
elements, one at a time •, they are now about to investigate the com- 
pounds of another of those elements ; that is all. But it is an ele- 
ment having a far greater range of combining powers than any yet 
examined. Organic chemistry is the chemistry of the element 
carbon. 



OEGANIO CHEMISTBY;* 

OR, 

THE CHEMISTRY OF CARBON COMPOUNDS. 



Introduction. 



Except alcohol and a few acids, the large number of compounds 
which have hitherto engaged notice in this Manual have been of 
mineral origin. But the two other kingdoms of nature, the animal 
and vegetable, furnish still larger numbers of definite substances. 
These latter compounds, indeed, when discovered, were producible 
only by organized living structures, and were hence termed organic 
(from bpyavov, org anon, an organ), and their study was termed or- 
ganic chemistry. A very large number of organic compounds can 
now, however, be obtained artificially, without the aid of a living 
organism ; hence the particular distinction formerly drawn between 
organic and inorganic compounds, organic and inorganic chemistry, 
no longer fully obtains. Another definition, or additional definition, 
of organic chemistry or the chemistry of animate nature, the laws 
of which do not differ from those of inanimate nature, is now gen- 
erally adopted — namely, the chemistry of carbon compounds. No 
doubt two or three kinds of compounds of carbon — carbonic acid gas 
and carbonates, for example — are met with in the mineral kingdom, 
and are therefore inorganic compounds ; but they are met with in the 
organic kingdoms too, and therefore are organic compounds also. 

Practically, all carbon compounds are organic compounds, and all 
of the so-called organic compounds are carbon compounds ; hence the 
old term, organic chemistry, no longer being etymologically and fully 
applicable, that of the chemistry of the carbon compounds seems 
natural as well as useful. Moreover, the carbon atoms possess in 
an altogether exceptional degree a property either not possessed, or 
only to a slight extent possessed, by those of other elements — 
namely, the property of combining with one another and forming 
a sort of chain, to every link of which atoms of other elements can 
be attached, the result being obviously molecules of almost infinite 
variety and complexity — a fact which alone suffices to secure for car- 
bon special and separate consideration by chemists. In short, the 
chemistry of the carbon compounds includes what was formerly as 
well as what is iioav known as organic chemistry ; or, in other words, 
the chemistry of organized or animate nature is included in the 



'' Bead the two previous pages of Advice to Students. 



384 ORGANIC CHEMISTRY. 

chemistry of the carbon compounds. Of course, so old and histor- 
ically interesting a term as organic chemistry will continue to be 
used ; and there is no objection to such use, provided students re- 
member that when the term is used as the equivalent of the chemis- 
try of the carbon compounds, it is only conventionally and not ety- 
mologically accurate. Moreover, the chemistry of a carbon compound 
includes the chemistry of every element in that compound and the 
chemistry of the compound as a whole — facts which obtain even 
more prominence if the chemistry be spoken of by a general word, 
such as organic, rather than by the specific word carbon. Indeed, 
an organic compound sometimes seems to be conditioned as much by 
its nitrogen as its carbon. The word organic having now in chem- 
istry lost its original specific signification, and having acquired the 
general signification described, it becomes, by its associations, per- 
haps the best word that can be chosen as the title of the great divis- 
ion of chemistry now under consideration. 

Composition of Organic Compounds. 

(a) Qualitative Composition. — The presence of carbon in a com- 
pound is at once shown if the compound blackens when a little is 
heated on a knife or platinum-foil in a flame. If the substance is 
heated in a dry, narrow test-tube, and much moisture is condensed 
on the upper cool part of the tube, the presence of hydrogen and 
oxygen is reasonably inferred. Nitrogen may be sought by care- 
fully but strongly heating in a test-tube a small portion of the sub- 
stance with a very small piece of potassium, and, after all action 
ceases, digesting the residue in water, filtering, and adding to the 
filtrate a ferrous salt, a ferric salt, and hydrochloric acid ; a precipi- 
tate of Prussian blue indicates nitrogen. Chlorine, bromine, iodine, 
sulphur, and phosphorus may be detected by heating the substance 
with nitric acid and nitrate of silver in a very carefully and strongly 
sealed tube (in a fume-chamber, with such precautions that if the 
tube burst no harm to the operator shall ensue), and testing the prod- 
uct for chlorides, bromides, iodides, sulphates, and phosphates by 
methods already described. 

(b) Quantitative Composition. — The qualitative composition of an 
organic substance being ascertained, the quantities of each element 
are then determined by methods which the student will practise when 
he is sufficiently advanced to work at the sections on quantitative 
analysis. The principles of the methods are, however, simple, and 
may at once be described. For the quantitative estimation of carbon 
and hydrogen a carefully weighed portion of the substance is com- 
pletely burned ; the products, which are, of course, carbonic acid 
gas and water, are collected and acurately weighed. Of every 44 
parts of the carbonic acid gas (C0 2 = 44), 12 will be carbon, and of 
every 18 parts of the water (II 2 = 18), 2 will be hydrogen ; in other 
words, three-elevenths of the weight of carbonic acid gas obtained 
will be the carbon of the original substance, while one-ninth of the 
water obtained will be the hydrogen of the original substance. If 
nitrogen be present, another carefully weighed portion of the sub- 



COMPOSITION OP COMPOUNDS. 385 

stance is heated with a mixture of soda and lime ; the nitrogen then 
takes up hydrogen and becomes ammonia, which is collected and 
accurately weighed ; of every 17 parts of ammonia (NH 3 = 17), 14 
will be nitrogen. The amounts of chlorine, sulphur, etc. — elements 
not often present — are obtained by subjecting carefully weighed por- 
tions of the original substance to the nitric treatment already alluded 
to, collecting and weighing the products, and calculating what pro- 
portions of the products are chlorine, sulphur, etc. The amount of 
oxygen is ascertained by difference ; that is to- say, the difference 
between the sum of the weights of carbon, hydrogen, nitrogen, etc. 
and the original weight of substance will be the weight of the oxygen 
in that original weight of substance. 

For example, a fluid having well-marked 'definite properties, and 
known to contain only carbon, hydrogen, and oxygen, is so burned 
that 0.3 of a gramme* of it yields 0.5738 of a gramme of carbonic 
acid gas and 0.3521 of a gramme of water. As three-elevenths of the 
carbonic acid gas and one-ninth of the water are hydrogen, it follows 
that the 0.3 of substance contains 0.1565 of carbon and 0.0391 of 
hydrogen ; and the difference between these two figures and 0.3 being 
0.1044, it follows that 0.1044 is the amount of oxygen in the 0.3 of 
original substance. For, 0.5738 X 3 -+- 11 = 0.1565 ; and 0.3521 -=- 
9 = 0.0391 ; 0.3 — (0.1565 + 0.0391) = 0.1044. 

(c) Centesimal Composition. — It is usual to make at least two such 
analyses of any organic compound, and as different weights of the 
original substance will almost necessarily be subjected to combustion 
(for it is easier to counterpoise by weights a selected quantity than 
it is to counterpoise with the substance any selected weights), the 
results of the combustions can only be compared by converting the 
numbers first obtained into percentages ; that is to say, by assuming 
in, for instance, the present case that not 0.3 parts of substance were 
operated on, but 100 parts. This is one of the simplest of arith- 
metical operations. If 0.3 of substance yields 0.1565 of carbon, 100 
of substance will yield 52.17 of carbon; if 0.3 of substance yields 
0.0391 of hydrogen, 100 of substance will yield 13.03 of hydrogen ; 
and if 0.3 of substance yields 0.1044 of oxygen, 100 of substarice'will 
yield 34.80 of oxygen. 

(d) Chemically Empirical Composition. — But the chemist further 
desires to know, not so much what percentages or ordinary unit- 
weights of elements arc contained in the compound, but what rela- 
tive number of chemical unit-weights or atomic weights are present 
— how many parts of carbon each weighing twelve, how many parts 
of hydrogen each weighing one, how many parts of oxygen each 
weighing sixteen, how many parts of nitrogen each weighing four- 
teen, etc. This, too, is one of the simplest of arithmetical operations. 
Divide the percentage of carbon by 12, of hydrogen by 1, of oxygen 
by 16, of nitrogen by 14, etc. Tims, in the present ease: 52.17 ■+■ 
12 = 4.347 atomic weights of carbon; 13.03 -s- 1 = 13.03 atomic 

* If the reader is not already familiar with the metric system of 
weights and measures, he is referred to the section on that subject in 
the latter part of the Manual. ( Vide Index, "Metric System.") 
33 



386 ORGANIC CHEMISTRY. 

weights of hydrogen; and 34.80 -5- 16 = 2.171 atomic weights of 
oxygen. Reducing these three fractional numbers of atomic weights 
to the lowest whole numbers (by assuming that the lowest of the 
three will represent 1 atomic weight — that is, by dividing the two 
higher of the three by the lowest), we find that the compound is 
composed of 2 atomic weights of carbon, 6 of hydrogen, and 1 of 
oxygen, thus : 4.347 -J- 2.171 = 2 of carbon ; 13.03 s- 2.171 = 6 of 
hydrogen ; 2.171 -J- 2.171 = 1 of oxygen. The result is, that of pro- 
portions of carbon each weighing 12, the substance contains 2; of 
proportions of hydrogen each weighing 1, the compound contains 6 ; 
and of proportion of oxygen each weighing 16, the compound con- 
tains 1. Finally, instead of the words " proportion of carbon weigh- 
ing 12," the simple capital letter C may be used, which, as the 
reader now well knows, is not only the short-hand or symbol for the 
word carbon, but stands for 12 parts of carbon. Similarly, H may 
stand for 1 part of hydrogen, and for 16 parts of oxygen ; whence 
we arrive at C 2 H 6 as the simplest chemically empirical expression, 
or empirical formula, of the substance under consideration. 

(e) Chemically Rational Composition. — From the empirical for- 
mula of a substance we pass to a two-volume formula ; that is to say, 
in accordance with the practice of chemists the formula must, if 
possible, represent two volumes of the substance when in the state 
of vapor (see pp. 53 and 57). Two parts of hydrogen gas, or seventeen 
of ammonia gas, or eighteen similar parts of water vapor, or forty-four 
of carbonic acid gas, or thirty-six and a half parts of hydrochloric 
acid gas, etc., occupy, if all are at the same temperature and under 
the same pressure, the same volume ; whence we derive the formulas 
II 2 . NH 3 , H 2 0, HC1, and C0 2 as formulae comparable with each other. 
If, now, the vessel which held these quantities of the respective sub- 
stances be filled with the vapor of the substance supposed to be under 
examination at the same temperature and pressure, and the vessel 
and contents be weighed, the contents will be found to weigh 46 
similar parts. C 2 H 6 will be found, on adding up the atomic 
weights, to represent 46 parts by weight. Therefore C 2 H 6 is the 
two-volume formula as well as the empirical formula, and thus the 
first step has been taken from the formula chiefly obtained by chem- 
ical art, an empirical formula, toward one largely obtained by and 
that satisfies the reason, or a rational formula or structural constitu- 
tional formula. Had the weight been found to be 92, the two-vol- 
ume formula would have been C 4 H 12 2 . The actual method of tak- 
ing these weights of equal volumes of gases and vapors (specific 
gravity and vapor-density) will be described in the paragraphs on 
quantitative analysis. 

(f) Molecular ^Composition. — Equal volumes of gases and vapors, 
being similarly affected by temperature and pressure, must be sim- 
ilarly constituted (Avogadro and Ampere's conclusion, pp. 52 and 53). 
Whatever the number of molecules in such equal volumes may be, 
it must be the same in each. Therefore the weights of equal bulk 
of gases and vapors under like conditions represent the relative 
weights of the respective molecules. Hence, 2, 17, 18, 44, and 36.5 
respectively represent the weight of one molecule of each of the 



CONSTITUTION OF COMPOUNDS. 387 

substances hydrogen, ammonia gas, water vapor, carbonic acid gas, 
and hydrochloric acid gas ; and 46 represents the molecular weight 
of the substance under consideration. C 2 H 6 therefore represents the 
composition of a molecule of the substance. C 2 H 6 is the molecular 
formula of the substance. (The substance is common alcohol.) 

Check on Composition. — If the formula found is, even so far, the 
true formula of the substance, the centesimal composition found by 
experiment ought to be practically the same — the same within the 
limits of experimental error — as the centesimal composition obtained 
by calculation from the formula, thus : — 

Calculated. Found. 

C 2 = 24 = 52.174 52.170 

H 6 = 6 = 13.043 13.030 

O = 16 = 34.783 34.800 

46 = 100.000 100.000 



From composition we now pass to constitution. What we know 
of the composition of a substance is reflected in its empirical for- 
mula. A step in advance is recorded in the molecular formula. "What 
is afterward learned about constitution is exhibited in the structural 
formula. 



Constitution of Organic Compounds. 

In the molecule of an organic compound how are the atoms 
arranged ? This is perhaps the greatest problem the chemist lias 
to solve. Like the toy-puzzles of our youth, these chemical puzzles 
have to be attacked analytically and synthetically. How to sep- 
arate into its constituent bars of wood that apparently solid cube 
given to us by a friend in old days was not an ungenial task, but, 
once accomplished, how to put those bars together again was a still 
more fascinating if more difficult labor. How to separate the groups 
of atoms or radicals in molecules of chemical substances, or at least 
how to find out the positions of those groups in a molecule, is a most 
difficult yet fascinating task for the skilled enthusiast in chemistry ; 
and how to so marshal those groups (drawn perhaps from several 
different sources, and visible and tangible only in a state of combi- 
nation and in mass) that he shall produce by art the compound 
originally only furnished by nature, is still more difficult, but also 
more fascinating. More fascinating, firstly, because it will furnish 
proof that his synthetical work was sound; secondly, because by 
artificially and perhaps cheaply producing a rare color, a rare per- 
fume, a rare flavor, or a previously costly medicine, he may become 
a benefactor to his fellow-man; and thirdly, because he may gain 
the honor of unveiling for all time one more of the truths of 
nature. 

In practically attacking the problem of the constitution o( a com- 
pound the chemist proceeds to note whether the substance is acid, 



388 ORGANIC CHEMISTRY. 

alkaline, or neutral ; to attack it with a base of known constitution 
if it is an acid, or with an acid of known constitution if it is a base, 
and to analyze the produced salts ; to oxidize it ; to deoxidize it ; to 
chlorinize it ; to remove or add hydroxyl (HO), carbonyl (CO), etc. ; 
to substitute hydrogen by a compound radical, and vice versa; to 
heat it ; to electrolyze it ; and, generally, to perform many such 
operations, in the hope that the lines of chemical cleavage in the 
molecule will be detected, the essential groupings of atoms in the 
molecule be discovered, and even the positions of atoms or groups 
of atoms in relation to each other be reasonably inferred. 

For example, urea, which was the first organic body produced 
artificially, was obtained by Wohler in 1828 on heating solution of 
cyanate of ammonium ; H 4 N0NO became 0C(NH 2 ) 2 , the mere 
change in the position of the constituent atoms — that is, in the 
structure of the molecules (indicated roughly, but to the best of our 
judgment, by the change in the position of the letters in the two 
formulae just given) — accounting for the differences in the proper- 
ties of the two substances, just as the differences in the position of 
a given number of stone blocks which at first were put together to 
form a bridge, but afterward were put tqgether to form a house — 
that is, the differences in the structure of the edifices — fully account 
for the differences in their properties. 

Notation of Organic Compounds. 

In order that we may convey to one another our conclusions 
respecting the constitution of organic compounds, notation has to 
be carried somewhat farther in organic than has already been shown 
to be necessary in inorganic chemistry. (See pages 41 and 55). The 
position of atoms and groups of atoms in a molecule may be indi- 
cated by placing the symbolic letters above or beneath one another 
as well as on one line, and the quantivalence of atoms, as well as 
the directions in which we conclude they are joined in the molecule, 
may be indicated by lines (— = or =) or dots ( • : : ) either com- 
pletely or only partially employed throughout the formula ; each dot, 
and, especially, each line or "bond," representing such union be- 
tween two neighboring atoms or radicals as would be represented by 
the extended arms of two persons shaking hands. For instance, the 
statement just made that cyanate of ammonium (H 4 NCNO) becomes 
urea [empirically CH 4 N 2 0, or rationally OC(XII 2 ) 2 ] might be repre- 
sented by either of the following forms of equation : — 

N = H 2 
H 4 = N — C = N = becomes = C<ll 

N = H 2 

N : H 2 
H 4 i N • C : N : becomes : C : •• 

N : H 2 

Here, bar*, in the first equation, and dots in the second, show 
not only the quantivalence, but especially the distribution of the 



CONSTITUTION OF COMPOUNDS. 389 

chemical power or affinity expressed by the quantivalence, of each 
atom. Thus the first four bars or dots not only indicate the univa- 
lence of each of the four hydrogen atoms on the one hand, and four- 
fifths of the quantivalence of the first nitrogen atom on the other 
hand, the next bar or dot showing the remaining fifth, but the five 
bars or dots also indicate that, of the total power or affinity of the 
nitrogen atom, four-fifths are engaged with a corresponding amount 
of attraction offered by four univalent hydrogen atoms, while the 
other fifth is engaged with one-fourth of the total power of the 
adjacent carbon atom. And so on with the quadri valence of the 
carbon atom, the quinquivalence of the second nitrogen atom, and 
the bivalence of the oxygen atom. 

But it is unnecessary, indeed undesirable, thus to indicate the quan- 
tivalence of each atom in a molecule, the closeness of union of groups 
of atoms (radicals) within a molecule being best indicated by putting 
the symbolic letters in a formula as close together as written charac- 
ters or printer's types will allow 5 moreover, an atom, such as that of 
nitrogen, may often pass from one degree of activity to another during 
a reaction. The following therefore are better arrangements : — 

H 4 N— CNO becomes = C<^ 2 

H 4 N • CNO becomes : C : (NH 2 ) 2 

Indeed, after a time the chemical student will find that his own 
imagination will often best supply that which is intended to be in- 
dicated by the lines or dots in the formulae of organic compounds, 
actual lines or dots only being employed where their use tends to 
promote clearness in a formula. For printed lines look like bars, 
and these, and even dots, are liable to suggest separation, whereas 
in a chemical formula they should suggest the union of the atoms 
and radicals in the molecule of which the formula is the crude pic- 
ture. While suggesting links and bonds, however, and the power 
(quantivalence or atomicity) of the atoms, they must be regarded as 
indicating lines of force rather than anything more substantial. Again, 
symbols and formulae, written or printed, are necessarily exhibited 
on surfaces, whereas the conception of a molecule should be that of 
a sphere — that of grapes on a bunch, or apples on a tree, rather than 
balls on a billiard-table ; or, still better, that of moons round a planet 
and planets round a sun, all kept in their places by force rather than 
by anything material. 

Finally, bars, dots, or what not must only be placed in a formula 
where actual experiment warrants, unless the statement is distinctly 
made or understood that the suggested formula is only hypothetical. 
The use of the following graphic rational formula or constitutional 
or structural formula, for example (for uric acid), is fully justified 
by a series of well-defined experiments : — 

UN— co 

I I 

CO C— NH 

^>CO 

o,« UN -C mi 



390 ORGANIC CHEMISTRY. 

Here, not only is the univalence of each of the hydrogen atoms, 
the bivalence of oxygen atoms, the trivalent character of each of the 
nitrogen atoms, and the quadrivalent nature of each carbon atom 
shown, either directly by bars attached to the symbols or suggestively 
by the position of a symbol of recognized quantivalence next to 
another symbol of recognized quantivalence, but the positions which 
experiment warrants us in believing that radicals occupy within the 
molecule are indicated in the formula by the position of the symbols 
for those radicals (HN, imidogen ; CO, carbonyl) round central atoms 
of carbon. 

To the student the great advantage of extended formulae, whether 
ordinary or graphic, consists in the relationships which they clearly 
exhibit between compounds which otherwise are not readily shown 
to be related to one another. 

The structural formulae characteristic of modern chemistry may 
be regarded as pictures of our idea of architecture in nature's mole- 
cules. The first sketches are seen in such formulae as HC 2 H 3 2 . 
Among the earlier, mid-century, artists were Gerhardt, Williamson, 
Frankland, and especially, from 1858 onward, Kekule. 



From the consideration of the composition and constitution of or- 
ganic compounds we now pass to the subject of classification. 



HYDROCARBONS: NEUTRAL OR NORMAL, AND 
BASYLOUS. 

Neutral or Normal Hydrocarbons. — The simplest compounds of car- 
bon are those with hydrogen, and as the atom of carbon is quadri- 
valent and the atom of hydrogen univalent, it follows that if a single 
atom of carbon be fully saturated with hydrogen, the formula of the 
resulting molecule must be CH 4 . But, as before stated, carbon is 
of all elements that which is peculiarly and specially liable to unite 
with itself, so far, at all events, as a portion of the attractive power 
of its atom is concerned, the other portions of its power attracting 
and being attracted by other atoms (as magnets attract each other); 
the result being, possibly, molecules of great complexity. The fol- 
lowing graphic formulae will illustrate this point : — 

H HH HHH HHHH 

H-C-H H-C-C-H H-C-C-C-H H-C-C-C— C-H 

I II III I I I I 
H HH HHH HHHH 

These formulae represent well-known hydrocarbons, the first being 
common marsh gas or methane, one molecule of which is otherwise 
represented by the shorter formula. CIL ; the next represents ethane. 
C 2 H 6 ; the third, propane, C 3 H S ; while CJI 10 is the formula of butane 
or tetrane. The first three members of the series are gases ; those 



HYDROCARBONS. 391 

which immediately follow are liquids, C 5 H 12 , C 6 II U , etc. ; while the 
highest members are solids, several of which form the mixture of 
hydrocarbons known as common paraffin ; indeed, the whole series 
is distinguished as the paraffin series of hydrocarbons. It will be 
observed that the four units of affinity of the carbon atom are, in the 
molecule of each substance, fully saturated either by the affinities of 
adjacent hydrogen atoms or by that of another carbon atom. The 
substances are illustrations of saturated hydrocarbons or neutral or 
normal hydrocarbons. They differ in composition by CH 2 ; add GH 2 
to the first, and you obtain the second ; add CH 2 to the second, and 
you obtain the third ; and so on. The members of this series resem- 
ble each other in containing, to a given number of carbon atoms, 
twice that number, with two added, of hydrogen atoms. Represent- 
ing " any number" by the letter n, the general formula for members 
of this neutral series of hydrocarbons will be C n II 2n+2 . Like neutral 
inorganic salts, their elements have saturated each other's affinities ; 
hence the molecules refuse further to unite by direct or indirect ad- 
dition with atoms having attractive powers. Potassium is powerfully 
basylous, chlorine powerfully acidulous, each has great affinity for 
the other ; but the product, chloride of potassium, KC1, is neutral or 
normal : saturated hydrocarbons are in the same case, for they do 
not unite with any other substances. 

Basylous Hydrocarbons. — Many hydrocarbon groups, such as 
" methyl," CH 3 , and " ethyl," C 2 H 5 , apparently have strong 
basylous affinities, because in compounds they appear to play the 
part which in inorganic compounds is performed by those basylous 
metals, etc. (K,NH 4 , Fe, etc.) which are commonly called inorganic 
radicals. Indeed, such hydrocarbon groups are often termed organic 
radicals, and to hold the theory that they exist is convenient ; but 
any attempt to isolate them results in the production of neutral 
hydrocarbons, C 2 H 6 , C 4 H 10 , etc. 

Some hydrocarbons, however, which can quite easily be isolated 
are basylous, such as ethylene, C 2 H 4 , and other bivalent radicals 
having the general formula C n H 2n ; and acetylene, C 2 H 2 , and other 
quadrivalent radicals having the general formula C u H 2n _ 2 . Such 
radicals are sometimes termed unsaturated hydrocarbons. 

I II II 

H— C— H H— C— C— H II— C— C— H 

I II II 

H H H 

Methyl? Ethylene? Acetylene? 

their compounds with, for example, bromine, being thus formu- 
lated : — 

Br Br Br Br Br 

I II II 

II— C— II II— C— C— II H— C— C— H 

I II II 

II 11 11 Br Br 



392 



ORGANIC CHEMISTRY. 



But the first is probably methane, in which one atom of hydrogen is 
substituted by one of bromine, other salts containing the supposed 
non-isolable radicals being normal hydrocarbons in which atoms of 
hydrogen are substituted by atoms of acidulous elements or acid- 
ulous radicals, the residual hydrocarbon being the so-called basylous 
radical. And as regards the basylous hydrocarbons which can be 
isolated, they too probably are neutral hydrocarbons in which the 
carbon atoms are united to the extent of half or even three-fourths 
of their affinities, thus : — 



H— C=C— H 

I I 
H H 

Ethylene. 



H— C=C— H 

Acetylene. 



Bring bromine into contact with these so-called free basylous rad- 
icals, and in the case of ethylene one pair of carbon " arms " may be 
considered to unclasp, each of the two free arms clasping a one- 
armed bromine atom ; while in the case of acetylene first one pair 
of arms unclasp and take in two bromine individuals, and then, 
another pair unclasp and take in two more individuals of a bromine 
molecule. 



Br— Br H— C=C— H 

Bromine. Acetylene. 



H— C=C— H 

I I 
Br Br 

Dibromide of 

acetylene ; or 

dibroin-ethylene. 



Br Br 

I I 
H— C— C— H 

I I 
Br Br 

Tetrabromide of 

acetylene ; or bromide of 

dibrom-etbylene ; or 

tetrabrom-ethane. 



Series of Hydrocarbons. — Three distinct series of hydrocarbons 
have now been alluded to — namely, the paraffin series, C u H 2u+2 ; the 
define series, C n H 2n ; and the acetylene series, C n H 2n _2. Twelve or 
fourteen other series are known, as, the terpene series, C n H 2n _ 4 ; the 
benzene series, C n Ii 2n _ 6 ; the cinnamene series, C n H 2n _ 8 ; the anthra- 
cene series, C n H 2n _ 18 , etc. Each member of any such series obvi- 
ously differs in composition from the preceding or succeeding mem- 
ber by CH 2 . Either series will therefore be an homologous series 
(from 6//oc, homos, the same, and lidyoq, logos, proportion) of com- 
pounds. 

Substitution. — The atoms of hydrogen in any member of either of 
the series of hydrocarbons may be substituted by radicals of all 
kinds — basylous -and acidulous, elementary and compound. Very 
large numbers of organic compounds have thus been obtained arti- 
ficially ; still larger numbers have been proved, analytically, to have 
distinct existence ; while it is certain that still larger numbers exist, 
of which we do not know the constitution and only partially know 
the composition. 



HYDROCARBONS. 393 

Several of these series of hydrocarbons and their substitutional 
derivatives will now be described, special notice being given to the 
compounds of medical and pharmaceutical interest. Some members 
of the paraffin, olefine, acetylene, terpene, benzene, naphthalene, and 
anthracene series will be treated of, together with their haloid, ni- 
trous, and acetic derivatives ; the alcohols or hydroxyl substitution 
compounds will then be noticed as a class ; and, afterward, the car- 
bohydrates, amyloids, aldehydes, acids, glucosicles, and alkaloids. 

A very large number of compounds of carbon will thus be brought 
under notice, far larger than that of any other element. The mere 
number, however, need not dismay the student. The relation of the 
derivatives of one hydrocarbon to that hydrocarbon will be found to 
obtain between the next set of derivatives studied with their hydro- 
carbon, and so on ; hence, as the student progresses he is soon 
looking for compounds which he already expects to exist, instead of 
finding his mind overburdened with what at first sight he might fear 
would be an intricate and endless subject. 

The methods of examining morbid urine will afterward be exper- 
imentally considered. There will then remain to be studied by the 
medical and pharmaceutical pupil, but by aid of some other guide 
than the authors, certain galenical as distinguished from chemical 
substances, solid and liquid, which can only be fairly regarded from 
a pharmacist's rather than a chemist's point of view, and a still 
larger number, doubtless, not yet brought within the grasp of chem- 
ist or pharmacist, and of which, therefore, we must at present be 
content to remain in ignorance. An opportunity, however, will be 
afforded of noticing the effect of such indefinite organic matter as a 
vomit or the contents of a stomach in masking or preventing the 
reaction-by which mineral and vegetable poisons are detected. 
A section on quantitative analysis will complete the Manual. 



QUESTIONS AND EXERCISES. 

669. What do you understand by Organic Chemistry ? 

670. Give methods of ascertaining the presence of carbon, hydro- 
gen, and nitrogen in organic compounds. 

671. Give an outline of the methods by which the quantities of 
carbon, hydrogen, oxygen, and nitrogen are determined in organic 
compounds. 

672. How would you convert centesimal into " atomic " composi- 
tion ? 

673. Define empirical, molecular, and rational formulae. 

674. How is the constitution of an organic compound ascertained? 

675. What do you understand by graphic chemical formulae? 
( !i ( i' ^ vc g ra phi° formulae of two or three saturated hydrocarbons. 

677. What do you mean by an organic radical ? Give illustrations. 

678. (Jive the general formulae or different series of hydrocarbons, 
with special illustrations. 

679. Define substitution as understood in organic chemistry. 



394 ORGANIC CHEMISTRY. 



THE PARAFFIN SERIES OF HYDROCARBONS. 

Methane, Marsh gas, Light carburetted hydrogen, Hydride of 
methyl, Fire damp, CH 4 . — This gaseous hydrocarbon occurs nat- 
urally in coal-mines and in the mud-volcanoes of the Crimea, 
and is constantly rising in bubbles to the surface of stagnant 
pools in marshy places. It is a non-luminous constituent of 
ordinary coal gas. It is inodorous and colorless. It may be 
produced by acting on iodide of methyl with zinc on which 
copper has been deposited, but is best obtained by heating a 
mixture of 2 parts of dry acetate of sodium, 3 of lime, and 2 
of caustic soda, or, better, potash. 

CH3.CO.ONa + NaOH = CH 4 + C0 3 Na 2 

Acetate of sodium. Soda. Methane. Carbonate of sodium. 

Two Notes on the Notation of the Foregoing and Similar For- 
mulo3 and on the Constitution of Salts. — (a) Soda, NaHO, contains 
bivalent oxygen, univalent sodium, and univalent hydrogen. The 
chemical power of the oxygen atom is double that of either of the 
other atoms, a relationship perhaps better realized if the symbol for 
the oxygen be placed between those of hydrogen and sodium, NaOH 
or HONa. So HOK, HOH, etc. The student must expect to find 
the symbols of a formula placed where apparently they will best 
reflect our knowledge of the structure of the molecule pictured. 
(b) Acetic acid, C 2 H 4 2 , by action of chlorine (presented as PC1 3 ) 
loses hyclroxyl, OH, and yields chloride of acetyl, C 2 H 3 0C1. Hence 
acetic acid would seem in constitution to be hydrate of acetyl, 
C 2 H 3 O.OH ; especially when we find that the chloride of acetyl 
by reaction with water, HOH, yields again acetic acid (and HCi). 
Sodium will only displace one atom of hydrogen from water, yield- 
ing HONa ; and will only displace one atom of hydrogen from 
acetic acid, yielding acetate of sodium, C 2 H 3 O.ONa. Further, chlo- 
rine will not displace more than one portion or atom of hydroxyl, 
OH, from acetic acid. So that three atoms of the hydrogen in 
acetic acid apparently perform different functions to those of the 
fourth atom ; and, apparently, the two atoms of . oxygen perform 
different functions. Hence our necessity for separating in the for- 
mula the letters representing those atoms, C 2 H 3 O.OH. Once more, 
acetates may be formed from two different methyl compounds : 
acetate of sodium by the direct combination of methide of sodium, 
CH 3 Na, and carbonic acid gas, C0 2 , giving CH 3 .CO.ONa ; and ace- 
tate of ammonium by the combination of methyl cyanide, CH 3 CN, 
with water (2HOH), yielding CH 3 .CO.ONH 4 . _ From these and 
other facts and modes of reasoning arises our justification — from 
them, indeed, comes the necessity — for thus extending the formulae 
for acetates. Less extended formulae are of course correct and even 
occasionally more useful : C 2 H 4 2 , C 2 H 3 2 H, C 2 H 3 O.OH, CH 3 .CO.OH 
form an illustration of a set of formulas for a substance either mem- 
ber of which set may be used according to circumstances. (See also 
pp. 285 and 298.) 



PARAFFIN HYDROCARBONS. 395 

Ethane, C 2 H 6 , Dimethyl, Hydride of Ethyl. — This is one of the 
constituents of crude petroleum. It also results on heating iodide 
of ethyl with granulated zinc or zinc covered with copper, and then 
adding water to the iodide of zinc and ethide of zinc first produced. 

2Zn + 2C 2 H 5 I == Zn(C 2 H 5 ) 2 + Znl 2 
Zn(C 2 H 5 ) 2 + 20H 2 = 2C 2 H 6 + Zn(OH) 2 . 

Ethane is sometimes regarded as dimethyl or methyl-methane, 
CHgCH, ; that is to say, as being derived from methane by the sub- 
stitution of an atom of hydrogen in methane, CH 4 , by methyl, CII 3 ; 
its properties, however, are not those of a radical. It is also con- 
sidered to be hydride of ethyl, C 2 H 5 H ; its properties, however, are 
not those of such a substance. The other hydrocarbons of the 
paraffin series are also similarly regarded as containing radicals. 
Such views of constitution are useful, as enabling composition to 
be remembered and relationships to be realized, especially if their 
hypothetical character be fully recognized ; but these hydrocarbons 
are apparently single homogeneous substances, and whatever other 
views of their constitution be held, this last should be dominant. 

Propane, methyl ethyl, C 3 H 8 . — This gas, like methane, occurs dis- 
solved in the Pennsylvanian petroleum springs. 

Tetrane or Butane, C 4 H 10 . — Two varieties exist — normal butane 
or diethyl, C 2 H 5 .C 2 H 5 , found in petroleum, and iso-butane or tri- 
methyl methane, CH(CH 3 ) 3 , formed by artificial means. 

Turning back to the highly extended formulas for methane, ethane, 
propane, and butane given on p. 389, the reader will see why there 
should only be one ethane or propane, while two butanes are pos- 
sible. We can but replace one of the atoms of hydrogen, H, in 
methane, CH 4 , to form ethane, CH 3 .CH 3 , and it matters not which ; 
hence only ethane (one ethane) can result. In ethane, CH 3 .CII 3 , if 
an atom of hydrogen be displaced by methyl, CH 3 , it can but be a 
hydrogen atom of one of the two methyl groups (CH 3 .CH 3 ), and it 
matters not which. But in propane, CH 3 .CH 2 CII 3 , a CH 2 group 
exists, as well as CII 3 groups. Now CH 2 is a different group to 
CH 3 ; hence if we displace one of its two atoms of hydrogen (it 
matters not which) by methyl to get butane, we should expect to 
get a butane of different properties to the butane obtained by dis- 
placing one of the atoms of hydrogen in the methyl groups by 
methyl; and two butanes, and two only, do actually exist. Nor- 
mal butane may be thus formulated, CH 3 .CH 2 .CH 2 .CH 3 , while iso- 
butane would be either CH 3 .CII 3 .CH.CII 3 , or a practically identical 
formula, CH^CII.CIIs.CI^. 

H H H H HCH 3 H II II H 

I I I I III III 

H— C— C— C— C— H H— C— C— C— H or H— C— C— C— II 

I I I I III III 

H H II H II II H IICII3II 

Butane. Isolmtuno. 

Pentane, C 5 II 12 . — Three varieties are possible, and three only ; 



396 ORGANIC CHEMISTRY. 

three are known, and three only ; the second, or isoamylic hydride, 
yielding the ordinary Aniylic Alcohol and Valerianic Acid. 

Hexanes, C 6 H 12 . — Five are possible, five are known. 

Heptanes, C 7 H 16 . — Nine are possible, four are known. 

Octanes, C 8 H 18 . — Eighteen possible, three known. 

Nonane, C 9 H 20 ; Decane, C 10 H 22 ; and paraffin hydrocarbons up to 
Hexdecaxe, C 16 H 34 , as well as derivatives of far higher members of 
the paraffin series of hydrocarbons, are known. 

Benzin, Petroleum Ether, Petroleum Benzin, Paraffin Oil, 
Paraffin— C 10 H 12 ,C 12 H 14 — and Homologous Compounds. 

Benzin, U. S. P. (pentane, C 5 H 12 , liexane, C 6 H U ), known also as 
benzol ine and petroleum spirit, " the purified distillate from Amer- 
ican petroleum, consisting of the hydrocarbons of the marsh gas 
series, a transparent, colorless, diffusive liquid, of a strong, charac- 
teristic odor, slightly resembling that of petroleum, but much less 
disagreeable ; neutral in reaction ; insoluble in water, soluble in 
about 6 parts of alcohol, and readily in ether, chloroform, benzol, 
and fixed volatile oils. Boiling-point, 50° to 60° C. (122 to 140° F.). 
Specific gravity, about 0.670 to 0.675." (Benzine or benzol is quite 
a different fluid ; vide Index.) 

Paraffin Oil, the Paraffinum Liquidum of the German Pharma- 
copoeia, is a mixture of the higher fluid members of the paraffin 
series of hydrocarbons, a clear oily liquid obtained from petroleum 
after distilling off the lower-boiling portions. Specific gravity, not 
below 0.840. Boiling-point, not below 360° C. (680° F.). Digested 
and agitated with warm sulphuric acid for a day or two, the oil is 
not colored and the acid only tinged brown ; metallic sodium under 
similar conditions is not tarnished ; alcohol boiled with the oil 
should not become acid. Petrolatum, U. S. P., Soft Paraffin (Paraf- 
finum Molle, B. P.), officially termed Unguentum Paraffini in Ger- 
many and Petroleine in France, and known in commerce by various 
fanciful names, is a semi-solid mixture of paraffins, usually obtained 
bv purifying the less volatile portions of petroleum. It has a melt- 
ing-point about 40° C. to 51° C. (104° F. to 125° F.), the first consti- 
tuting the softer, and the second the firmer, variety. It is " a yellow- 
ish or yellow, fat-like mass, transparent in thin layers, more or less 
fluorescent, especially when melted, completely amorphous, tasteless, 
and odorless, or giving off, at most, only a faint petroleum odor when 
heated, and having a neutral reaction. When gently heated, until 
the mass is almost entirely melted, the liquid portion has a sp. gr. 
varying from .835 to .860. It is insoluble in water, scarcely soluble 
in alcohol or in cold absolute alcohol, but soluble in 64 parts of 
boiling absolute alcohol, and readily soluble in ether, chloroform, 
disulphide of carbon, oil of turpentine, benzin, benzol, and in fixed 
or volatile oils. When heated on platinum-foil, it is completely 
volatilized without emitting the acrid vapors of boiling fat or resin." 
Hard Paraffin (Paraffinum Durum, B. P.), commonly termed paraf 



CHLOROFORM. 397 

fin wax or simply paraffin, is " a mixture of several of the harder 
members of the paraffin series of hydrocarbons ; usually obtained 
by distillation from shale, separation of the liquid oils by refrigera- 
tion, and purification of the solid product. It is colorless, semi- 
transparent, crystalline, inodorous, and tasteless ; slightly greasy 
to the touch. Specific gravity, 0.82 to 0.94. Insoluble in water, 
slightly soluble in absolute alcohol, freely soluble in ether. It 
melts at 110° to 145° F. (43.3° to 62.8° C), and burns with a bright 
flame, leaving no residue." 

Paraffin resists all ordinary reagents (hence the original name 
paraffin, from parum qffinis, without affinity), but may, by con- 
tinued boiling with sulphuric acid and solution of bichromate of 
potassium, be oxidized to cerotic acid, C 27 H 54 2 , and by continued 
digestion with nitric and sulphuric acids yields acids of the acetic 
series and parqffinic acid, C 24 H 48 2 (Pouchet). 



Substitution-products of Methane. — The paraffins all form sub- 
stitution-derivatives with the halogens, chlorine acting energetically, 
bromine less so, and iodine scarcely at all. In the preparation of 
chlorine and bromine substitution-products by acting on the hydro- 
carbons the mono-derivatives are always mixed with the higher de- 
rivatives, even though the quantities are taken in relation to their 
combining proportions 5 thus, if methane and chlorine are mixed in 
the proportion of CH 4 -j- Cl 2 , not only will monochloromethane, or 
chloride of methyl, CH 3 C1, be formed, but dichloromethane, CII 2 C1 2 , 
and trichloromethane, CHC1 3T with free hydrogen. The best method 
of obtaining the mono-derivatives is to act on the alcohols by haloid 
acids or by phosphorus compounds : — 

CH3OH + HC1 = CH3CI + H 2 
3CH 3 OH + PCI3 = 3CH 3 C1 + PH3O3. 

Chloroform. 

Trichloromethane, or chloroform, CHC1 3 , may be made by acting 
on methane with chlorine, as already indicated, 

CH 4 + 3C1 2 = CHC1 3 + 3HC1, 
but on a larger scale by the official process, as follows : — 

Process. — One fluidounce and a half of spirit and 24 of water 
are placed in a retort or flask of at least a quart capacity ; 8 
ounces of chlorinated lime and 4 of slaked lime are added, the 
vessel connected with a condenser, and the mixture heated until 
distillation commences, the source of heat then being with- 
drawn. The condensed liquid should fall into a small flask 
containing water, at the bottom of which about a drachm of 
chloroform will slowly collect. 

Explanation of the Process. — Though there is some doubt as to 
the exact reaction, the following seems to be most probable. The 



398 ORGANIC CHEMISTRY. 

hypochlorite of calcium believed to be present in the chlorinated lime 
(see the remarks in connection with the latter, p. 112) readily yields 
up oxygen and chlorine to organic substances, the calcium being 
liberated as hydrate. The alcohol used in making chloroform is 
thus probably first reduced to aldehyde : — * 

2CH 3 CH 2 OH + 2 = 2CH 3 COH + 2H 2 

Alcohol. Oxygen. Aldehyde. Water. 

The action of chlorine on aldehyde then probably gives chloral (chlor- 
aZdehyde) : — 

CH3COH + 3C1 2 = CCI3COH + 3HC1 

Aldehyde. Chlorine. Chloral. Hydrochloric 

acid. 

The nydrochloric acid being at once neutralized by some of the lib- 
erated hydrate of calcium to form chloride of calcium and water, 
more freed hydrate of calcium and chloral give formate of calcium 
and chloroform: — 

2CC1 3 C0H + Ca2HO = (HCOO) 2 Ca + 2CHC1 3 

Chloral. Hydrate of Formate of Chloroform, 

calcium. calcium. 

Or, neglecting the probable steps in the process, and regarding only 
the materials and the products, 4 molecules of alcohol and 8 of hy-» 
pochlorite of calcium give 2 of chloroform, 3 of formate of calcium, 
5 of chloride of calcium, and 8 of water, thus : — 

4CH 3 CH 2 OH + 8CaCl 2 2 = 

Alcohol. Calcium 

hypochlorite. 

2CHCI3 + 3(H.COO) 2 Ca + 5CaCl 2 + 8H 2 

Chloroform. Calcium Calcium Water, 

formate. chloride. 

The hydrate of calcium placed in the generating vessels _ is not es- 
sential, but is useful in preventing secondary decompositions, the 
hydrate of calcium obtainable from the reaction being insufficient 
for this purpose. 

Chlorine converts chloroform into tetrachloromethane or tetra- 
chloride of carbon, CC1 4 , completing the chlorine substitution-prod- 
ucts of methane. 



11 /CI /CI /CI 

i 4i 4% 4o\ 4c\ 



\H \H \H \C1 

Monochloro- Dichloro- Trichloromethane Tetrachloro- 

methane. methane. (chloroform). methane 

(carbon tetrachloride). 

Chloroform is purified by shaking it with water, and then with 
pure sulphuric acid (containing no trace of nitric acid), which chars 

*The special formulae for alcohol, aldehyde, and formates used in the 
accompanying equations will be better understood when the constitution 
of alcohols and acids has been considered. 






IODOFORM. 399 

and removes hydrocarbons, etc., but does not affect chloroform. It 
is freed from any trace of acid by agitation with lime, and from 
moisture by solid chloride of calcium. 

Properties. — The sp. gr. of chloroform is at least 1.500, perhaps 
higher. It is liable to slowly decompose when exposed to air and 
light. To render it stable a minute amount (1 volume in 100, or 
less) of absolute alcohol is necessary ; hence the specific gravity of 
medicinal chloroform is about 1.497 (1.485-1.490, Chloroformum 
Purification,, U. S. P.). It readily and entirely volatilizes at common 
temperatures, having, to the last drop, its pleasant characteristic 
odor. It has a sweetish taste, is limpid, colorless, soluble in alcohol 
(1 to 9 gives Spiritus Chloroformi, U. S. P.) and ether, and slightly 
in water. Boils at 142° F. It burns with a sluggish, green, smoky 
flame. It should be neutral to test-paper, indicating absence of acid ; 
give no precipitate with solution of nitrate of silver, indicating ab- 
sence of ordinary chlorides ; remain colorless when heated with 
potash, indicating absence of aldehyde ; and give no more color than 
is producible by the absolute alcohol that is present to any sulphuric 
acid with which it may be shaken, even after the mixture has been 
set aside for half an hour, indicating absence of hydrocarbons, etc. 
Alcohol may be detected by the iodoform test (see Index), or by 
shaking with a little of the dye termed " Hofmann's violet," which 
gives the chloroform a purple tint if alcohol be present, but affords 
no color with pure chloroform. At the temperature of melting 
ice chloroform unites with water to form a crystalline compound, 
CH01 3 .18H 2 O. 

Commercial Chloroform ( Chloroformum venale, U. S. P.) should 
have a sp. gr. not lower that 1.470 at 15° C. 

Aqua Chloroformi, B. P., Chloroform Water, is made by shaking 
1 fluiddrachm of chloroform with 25 ounces of distilled water till 
dissolved. 

Iodoform. 

Tri-iodomethane, or iodoform, CHI 3 (Iodoformum, U. S. P.), 
analogous in constitution to chloroform, the iodine occupying 
the place of the chlorine, is made by mixing in a retort 1 part 
of alcohol, 2 parts of crystallized carbonate of sodium, and 10 
parts of water ; the whole being heated at about 150° F., and 1 
part of iodine gradually added in small portions. When the 
fluid becomes colorless, it is poured into a beaker and allowed 
to settle. The iodoform is collected on a filter, washed 
thoroughly with water, and dried between filtering-paper. 
(This reaction forms a very delicate means of testing the pres- 
ence of alcohol. Vide " Alcohol, test for," in Index.) 

Iodoform occurs as yellow, shining, six-sided scales. Tt is volatile 
at ordinary temperatures, almost insoluble in water, soluble in al- 
cohol or ether. Warmed with an alcoholic solution o( potash, 
formate and iodide of potassium are produced, CHI a 4K011 
= K000K + 3KI + 211,0: and the resulting lluid. heated with 



400 ORGANIC CHEMISTRY. 

a little nitric acid, yields free iodine, recognized by its color or by 
giving a blue color with starch. Sp. gr. 2.000. 

Chloroform, iodoform, and bromoform may also be obtained on 
passing a current of electricity through hot strong alcohol containing 
chloride, iodide, or bromide of potassium respectively, carbonic an- 
113-dride being simultaneously supplied. 

Substitution-products of Ethane. — Ethane, like methane, 
yields substitution-derivatives. Monobromethane, bromide of 
ethyl, ethylic bromide, or hydrobromic ether. C 2 H 5 Br, may be 
prepared by gradually adding 4 parts of bromine to a mixture 
of 45 parts of ethylic alcohol and 4 of amorphous phosphorus 
contained in a flask fitted with an upright condenser, care being 
taken to keep the apparatus cool. 

5C 2 H 5 OH + PBr 5 = 5C 2 H 5 Br + H 3 P0 4 +H 2 0. 

When all the bromine has been added, the mixture is poured 
into a retort and distilled over a water-bath, the resulting 
ethylic bromide freed from excess of bromine by washing with 
a small quantity of dilute soda or potash, then washed with 
water and rectified over calcium chloride and redistilled. 

For its preparation on a large scale De Vrij's method is preferable, 
C 2 H 5 HS0 4 + KBr = C 2 H 5 Br-hKHS0 4 (see Pliarm. Journ., Feb. 15, 
1879), or the same method as modified bv Green (P. J., July 12, 
1879). by Reminoton (P. /., May 29, 1880), or by Wolff (P. /., July 
3, 1880). 

Mon-iodoethane, iodide of ethyl, or ethylic iodide, C 2 H 5 I, may 
be made, like the bromide, by mixing 7 to 8 parts of amorphous 
phosphorus and 70 of absolute alcohol with 100 parts of iodine. 
The complete decomposition takes three or four hours, after 
which it may be treated as above. It should be kept in a 
dark place, as light favors decomposition and liberation of 
iodine. 

The paraffins give rise to many substitution-derivatives by dis- 
placement of their hydrogen by compound acidulous radicals. The 
following, chiefly from ethane and pentane, are of pharmaceutical 
interest : — 

Spirit of Nitrous Ether. 

Nitrite of Ethyl, Nitrous Ether. C 2 TI 5 X0 2 . — A "spirit" probably 
containing nitrous ether was one of the earliest known medicinal 
compounds, its discovery being generally ascribed to Raymond 
Lully. 

Process. — To a third of a test-tubeful of rectified spirit add 
about a tenth of its bulk of sulphuric acid, rather more of 






SPIRIT OF NITROUS ETHER. 401 

nitric acid, and warm the mixture ; as soon as ebullition com- 
mences the vapor of nitrous ether (with other substances) is 
evolved, recognized by its odor. A long bent tube, kept very 
cool, may be adapted by a perforated cork to the test-tube, and 
thus a little of the product be condensed and collected. 

The above process, conducted on a larger scale, with definite quan- 
tities of materials, temperature regulated by a thermometer, and a 
well-cooled condenser, etc. etc. (see p. 126), is the official process for 
the preparation of a concentrated solution of nitrous ether, etc., in 
spirit 5 diluted with nearly three times its bulk of rectified spirit, 
it forms the official variety of the " spirit of nitrous ether "(Spiritus 
jEtheris Nitrosi, U. S. P.) of pharmacy, containing about 5 per cent, 
of the crude ether. 

" Take of— 

Nitric Acid 9 parts, 

Sulphuric Acid 7 parts, 

Alcohol, 

Distilled water, each a sufficient quantity. 

u Add 7 parts of sulphuric acid gradually to 31 parts of alcohol. 
When the mixture has cooled transfer it to a tubulated retort con- 
nected with a well-cooled condenser, to which a receiver, surrounded 
by broken ice, is connected air-tight, and which is further connected 
by means of a glass tube with a small vial containing water, the 
end of the tube dipping into the latter. Now add 9 parts of nitric 
acid to the contents of the retort, and, having introduced a thermom- 
eter through the tubulure, heat rapidly, by means of a water-bath, 
until strong reaction occurs and the temperature reaches 80° C. (176° 
F.). Continue the distillation at that temperature, and not exceed- 
ing 82° C. (180° F.), until reaction ceases. Disconnect the receiver, 
and immediately pour the distillate into a flask containing 16 parts 
of ice-cold distilled water. Close the flask and agitate the contents 
repeatedly, keeping down the temperature by immersing the flask 
occasionally in ice-water. Then separate the ethereal layer, and mix 
it immediately with 19 times its weight of alcohol. Keep the prod- 
uct in small glass-stoppered vials in a dark place, remote from lights 
or fire." 

Disregarding other products, the following equation represents the 
chief decompositions that occur in the operation. The main point 
in the reaction is the reduction of the nitric to the nitrous radical by 
the hydrogen of some of the alcohol, which is thereby reduced to 
aldehyde. The sulphuric acid absorbs water. 

2C 2 H 5 OH ■ + UNO, = C 2 H 5 N0 2 + 211,0 + 0,11, 

Alcohol. Nitric acid. Nitrous other. Water. Aldehyde. 

Properties. — Spirit of Nitrous Ether is a "clear, mobile volatile. 
and inflammable liquid, of a pale straw-color, inclining slightly to 
green, a fragrant ethereal odor free from pungency, and ;i sharp, 
burning taste. Sp. gr. (J.82;> to 0.825. It slightly reddens litmus- 



402 ORGANIC CHEMISTRY. 

paper, but should not effervesce when a crystal of bicarbonate of 
potassium is dropped into it. "When mixed with half its volume of 
solution of potassa, previously diluted with an equal volume of 
water, it assumes a yellow color, which slightly deepens, without 
becoming brown, in twelve hours. A portion of the spirit, in a test- 
tube half filled with it, plunged into water heated to 63° C. (145.4° 
F.), and held there until it has acquired that temperature, should 
boil distinctly on the addition of a few small pieces of glass." 

The great tendency of aldehyde to become converted into acetic 
acid by the absorption of oxygen from the air renders Spirit of 
Nitrous Ether unstable, and pharmacists are obliged to neutralize 
such acid, generally by bicarbonate of potassium, before adding it 
to medicines containing iodides, etc. 

" Test (U. S. P.). — If 10 gm. of spirit of nitrous ether be mace- 
rated with 1.5 gm. of potassa for twelve hours, with occasional agi- 
tation, the mixture then diluted in a beaker with an equal volume 
of water, and set aside until the odor of alcohol has disappeared, 
then slightly acidulated with diluted sulphuric acid, and a solution 
of 0.335 gm. of permanganate of potassium gradually added, the 
color of the whole of this solution should be discharged (presence of 
at least 4 per cent, of real ethyl nitrite)." 

The nitrous radical may be detected by adding sulphate of iron 
and sulphuric acid to some of the spirit of nitrous ether, a brown 
or black compound being produced, already explained in connection 
with nitric acid. 

Official (B. P.) Test of Strength. — " Tested as described in the 
Pharmaceutical Journ., 3d series, vol. xiii. p. 63 [Eykman's test, 
2FeS0 4 -f H 2 S0 4 + 2C 2 H 5 N0 2 = Fe 2 3S0 4 + 2C 2 H 5 HO + 2NO, a fig- 
ure of the apparatus is given], or vol. xv. p. 101 [Dymond's mod- 
ification of Eykman's apparatus], or vol. xv. p. 673 [Allen's mod- 
ification], it [the British preparation] should yield, at the ordinary 
temperature (60° F.. 15.5° C.) and pressure (30 inches, or 760 milli- 
metres of mercury), and when freshly prepared, seven times its 
volume of nitric oxide gas ; and even after it has been kept some 
time and the vessel containing it has occasionally been opened, it 
should yield not much less than five times its volume of the gas." 
If the gas were yielded by nothing but nitrite of ethyl, the seven 
volumes would correspond to nearly 3 per cent, of that substance, 
and the five volumes to nearly 2 per cent. Simonson says the prep- 
aration official in the United States Pharmacopoeia also contains 
from 2 to 3 per cent, of nitrite of ethyl. 

(For the detection of methyl alcohol in spirit of nitrous ether, vide 
"Methylated Sweet Spirit of Nitre" in Index.) 

Pure Nitrite of Ethyl. 
Dr. Leech has shown that both the physiological and the thera- 
peutic actions of "spirit of nitrous ether" are similar to that of a 
solution of nitrite of ethyl of similar strength. The latter solution 
was prepared for Dr. Leech, in the Research Laboratory of the Phar- 
maceutical Society of Great Britain, by Hare's process of mixing 
nitrite of potassium, sulphuric acid, and alcohol at a low tempera- 



ACETIC ETHER. 403 

ture. The nitrite of ethyl then separates as a pale-yellow layer. 
It may be washed rapidly with a little water, and dried with anhy- 
drous carbonate of potassium. It is decomposed by prolonged con- 
tact with water ; hence Dunstan recommends the use in medicine of 
a solution of two parts of the ether in absolute alcohol containing, 
as previously suggested by Williams, 5 per cent, of glycerin, and 
that it be dispensed and used from small bottles to avoid loss by 
volatilization. 
2NaN0 2 + H 2 SO, + 2C 2 H 5 OH = 2C 2 H 5 N0 2 + Na 2 S0 4 + 2H 2 

Nitrite of Sulphuric Hydrate of Nitrate of Sulphate of Water, 

sodium. acid. ethyl. ethyl. sodium. 

Nitro-ethane. — There are two derivatives of ethane, having similar 
composition, but differing very much in properties — namely, nitrite 
of ethyl (C 2 H 5 N0 2 ), which boils at 63.5° F. (17.5° C.) and has a sp. 
gr. of 0.900 (at 0° C. ; water = 1 ; 0.917 to 0.920, Dunstan and Dy- 
mond) 5 and nitro-ethane (C 2 H 5 N0 2 ), which boils at about 235° F. 
(nearly 113° C.) and has a sp. gr. of 1.058. The former is easily 
decomposed, the latter stable. The official spirit of nitrous ether 
contains nitrite of ethyl. Possibly the nitrite of ethyl contains the 
nitrogen in the trivalent or unsaturated condition, while in the nitro- 
ethane it is in the quinquivalent or saturated state. Thus : — 

C 2 H 6 C 2 H 5 -0-N = C 2 H 6 -N^° 

Ethane. Nitrite of ethyl. Nitro-ethane. 

Acetic Ether, or Acetate of Ethyl. 

Acetate of Ethyl, or Acetic Ether, CH 3 .CO.OC 2 H 5 or 
C 2 H 5 C 2 H 3 2 . — To a little dried acetate of sodium in a test- 
tube add a small quantity of rectified spirit of wine and 
some sulphuric acid, and, adapting a long bent tube in the 
usual manner, heat the test-tube and so distil over acetic 
ether ; which may be collected in another test-tube kept 
cool by partial immersion in cold water. 

The official proportions {JEther Aceticus, B. P.) are: rectified 
spirit, 32^ fluidounces ; sulphuric acid, 32£ fluidounces; acetate 
of sodium, 40 ounces ; carbonate of potassium, freshly dried, 6 
ounces. It is purified from any water by shaking in a bottle 
with fused chloride of calcium, and after twenty-four hours rec- 
tifying. It is a colorless liquid with an agreeable ethereal odor. 
JEther Aceticus, U. S. P., has the specific gravity 0.889 to (1897. 
Boiling-point, about 76° C. (168° F.). Soluble in all proportions in 
rectified spirit and in ether. When 10 c.c. are agitated with an 
equal volume of water, in a graduated test-tube, the upper, ethereal 
layer, after its separation, should not measure less than 9 c.c. 
C 2 H 5 OH + CH3.CO.ONa + IT..SO, 

Hydrate of Acetate of Sulphate of 

ethyl. sodium. hydrogen. 

= CH,.CO.OC 2 lI- ) I NallSO, + 1IOII 

Acetate of ' Sulphate of sodium Hydratoof 
ethyl. and hydrogen. hydrogen. 



404 ORGANIC CHEMISTRY. 

Acetate of Amyl, CHg.CO.OCjH^ or C 5 H n C 2 H 3 2 .— (Fousel oil, or 
ordinary aniylic alcohol, is a mixture of two or more alcohols 
derived from pentane, but the derivatives may he simply termed 
amyl compounds ; vide Pentylic or Amylic Alcohol.) 

To a small quantity of amylic alcohol in a test-tube add some 
acetate of potassium and a little sulphuric acid, and warm the 
mixture ; the vapor of acetate of amyl is evolved, recognized by 
its odor, which is that of the jargonelle pear. If a condensing- 
tube be attached, the essence may be distilled over, washed by 
agitation with water, to free it from alcohol, and separated by 
a pipette: 

CH3.CO.OK + C 5 H n OH + H 2 S0 4 == 

Acetate of Amylic Sulphuric 

potassium. alcohol. acid. 

CH 3 .CO.OC 5 H n + KHSO, + H 2 

Acetate of Acid sulphate Water, 

amyl. of potassium. 

Fruit-Essences. — Acetate of amyl, prepared with the proper equiv- 
alent proportions of constituents, as indicated by the above equation, 
is largely manufactured for use as a flavoring agent by confectioners. 
Valerianate of amyl (C 5 H n C 5 H 9 2 ) is similarly used under the name 
of apple-oil. Butyrate of ethyl (C 2 H 5 C 4 H 7 2 ) closely resembles the 
odor and flavor of the pine-apple ; oenanthylate of ethyl (C 2 H 5 C 7 H ]3 2 ) 
recalls greengage 5 pelargonate of ethyl (C 2 H 5 C 9 H 17 2 ) quince ; sube- 
rate of ethyl "(C 2 H 5 C 8 H 12 4 ), mulberry; sebacate of ethyl (C 2 H 5 C 10 - 
H 16 4 ), melon. Salicylic aldehyde, salicylol or salicylous acid, CgH^- 
OH.COH, is the essential oil of meadow-sweet {Spiraea ulmaria), 
and may be prepared artificially by the oxidation of salicin {vide 
Index, " Salicin "). Acid salicylate of methyl (CH 3 HC 7 H 4 3 ) or 
gaultheric acid forms the chief part of the essential oil of winter- 
green {GauWieria procumbens, the fresh leaves of which yield about 
0.4 per cent, of oil). Oil of sweet birch {Betula lento) is salicylate 
of methyl. The latter may also be prepared artificially from salicin 
and by heating chloroform and sodium phenol. Salicylic acid (C 6 H 4 .- 
OH.COOH) can easily be obtained from the salicylate of methyl, but 
more cheaply from carbolic acid. 

By mixing ethereal salts with each other and with essential oils in 
various proportions the odor and flavor of nearly every fruit may be 
fairly imitated. (For a set of formulae of fruit-essences see Pharma- 
ceutical Journal, May 17, 1879.) 

Nitrite of Amyl. 

Nitrite of Amyl {Amyl Xitris, IT. S. P.) (C 5 H u N0 2 ).— This may be 
prepared on the large scale by the direct action of nitric acid on 
amylic alcohol, the nitric acid being reduced to nitrous by a portion 
of the alcohol, and valerianic aldehyde with valerianic acid being 
produced. The heat must be very carefully regulated, or the action 
may become extremely violent ; indeed, with small quantities a vio- 
lent explosion may occur, 



AMYL SALTS. 405 

For experimental purposes it is preferable to pass nitrous gases, 
generated by the action of nitric acid on white arsenic or on starch, 
into the ainylic alcohol (kept cool by standing the vessel in cold 
water) until the alcohol is saturated. The product is shaken with 
an aqueous solution of hydrate or carbonate of potassium, to remove 
free acids, and the oily liquid then separated is distilled, the portion 
distilling between 205° and 212° F. being amyl nitrite. 

The official nitrite of amyl is a yellowish ethereal liquid ; sp. gr. 
of liquid 0.874, of vapor 4.U3 ; boiling-point, about 96° C. (205° F.) ; 
soluble in spirit of wine, insoluble in water ; converted by fused 
caustic potash into valerianate of potassium; exposed to the air, it 
yields amylic alcohol. If of good quality (for physiological pur- 
poses, although perhaps not chemically pure), about 70 per cent, 
will distil between 194° and 212° F. (90° to 100° C), the bulb of 
the thermometer being in the vapor and not touching the residual 
fluid. 

The official and commercial varieties of "nitrite of amyl" are 
well known to be only chiefly real nitrite of amyl. The staff of the 
Research Laboratory of the Pharmaceutical Society of Great Britain 
have recently shown that the fluid may contain the nitrites of both 
alpha-amyl and beta-amyl, nitrite of iso-butyl and nitrite of propyl, 
and have furnished specimens of these substances tc Professor Cash, 
who is investigating their physiological and therapeutic properties. 
These nitrites are of course derived from the hydrates (see pp. 443 
and 444) in the amylic alcohol. 

Nitropentane (C 5 H n N0 2 ) is another derivative of pentane, similar 
to nitrite of amyl in composition, but differing much in properties. 
It is obtained by reaction of iodide of amyl on nitrite of silver. It 
boils at-300° to 320° F. The remarks made respecting the two sim- 
ilar derivatives of ethane (p. 469) may be applied to those of pentane. 



QUESTIONS AND EXERCISES. 

680. How would you prepare methane and ethane ? Give formula?. 

681. Give details of the production of chloroform from alcohol, 
tracing the various steps by equations. 

682. Give the formulae and state the constitution of the various 
chlorine derivatives of methane. 

683. How is chloroform purified ? 

684. State the characters of pure chloroform. 

685. Explain the official process for the preparation of nitrous 
ether. 

686. Give the properties of nitrous ether as compared with nitro- 
ethane. 

687. Ry what official method is the strength of spirit of nitrous 
ether to be estimated? 

688. How is iodide of ethyl made? 

689. Mention the systematic names of several artificial fruit- 
essences. 

690. What is the formula of nitrate of amyl? and how is it 
prepared? 



406 " ORGANIC CHEMfSTRY. 



THE OLEFINE SERIES OF HYDROCARBONS. 

The define Series of Hydrocarbons consists of unsaturated hydro- 
carbons having the general formula C n H 2n . Ethylene, C 2 H 4 ; Pro- 
pylene, C 3 H 6 ; Butylene, C 4 H 8 ; Amylene, C 6 H 10 ; Hexylene, C 6 H 12 ; and 
Heptylene, C 7 H U , are well known. 

Ethylene, Olefiant Gas, or Heavy Carouretted Hydrogen, C 2 H 4 , is 
the first of this series. It is formed in the destructive distillation of 
coal, and is the chief illuminating constituent of coal gas. Coal gas 
consists of 30 to 40 per cent, of methane, 40 to 50 per cent, of hydro- 
gen, and from 5 to 7 per cent, of ethylene and its homologues. Hy- 
drocarbons, normally fluid, but kept in the vaporous condition by the 
diluents, also contribute materially to the illuminating power of gas. 
The impurities are nitrogen, air, carbolic acid, bisulphide of carbon, 
CS 2 , and some badly smelling sulphur compounds. Upward of one 
hundred and fifty distinct chemical substances have been obtained 
from the solid, liquid, and gaseous products of the destructive distil- 
lation of coal. 

Preparation. — Ethylene may be prepared by dropping alco- 
hol into a large retort or flask containing 10 ounces of sulphuric 
acid and 3 ounces of water heated to 160°-165° C. The gas is 
washed in cold water and a solution of soda, to free it from 
ether, alcohol, and sulphurous acid : — 

C 2 H 5 OH + H 2 S0 4 = C 2 H 5 HS0 4 + H 2 0. 

Alcohol. Sulphuric Ethylhydrogen Water, 

acid. sulphate. 

The product, when further heated, yields ethylene, — 

C 2 H 5 HSO, = C 2 H 4 + H 2 S0 4 . 

If the ethylene be passed into bromine under water until all the 
bromine disappears, ethylene dibromide, C 2 H 4 Br 2 , or dibrom-ethane, 
will be formed. 

Properties. — A colorless, odorless, condensable gas, burning with 
a luminous flame. 

Ethylene Sulphate, C 2 H 4 S0 4 , is probably contained in the Spiritus 
^Etheris Compositus, U. S. P., a solution of 3 parts of ethereal oil in 
30 of stronger ether and 67 of alcohol. The so-called ethereal oil or 
heavy oil of wine is obtained by digesting spirit of wine and sul- 
phuric acid together, then distilling, removing any acid from the 
distillate by washing with lime-water, and exposing the ethereal 
fluid to the air to facilitate escape of the more volatile fluids. The 
product is a mixture consisting probably of ethylene sulphate, ethyl 
sulphate, ether, dissolved ethylene, and other bodies. 

Glycols. — The defines form dihydric alcohols or glycols (named 
from glycol, the first member of -the series), and these give two sets 
of aldehydes and acids. Thus, — 



OLEFINE HYDEOCARBONS. 407 

CH 2 0H COH 

I I 

COH COH 

CH 2 0H CH.OH Glycolic Glyoxalor 

I * I * aldehyde. Oxalic aldehyde. 

CH 2 OH CH 2 OH CH s OH COOH 

Glycol. Glycol. 

COOH COOH 

Hydroxyacetic acid Oxalic acid, 

or Glycollic acid. 

Relation of Paraffins to Olefines. 
1st. The paraffins may be converted into olefines either by acting 
on an alcohol of the paraffin series by sulphuric acid, or by acting on 
a monochloro-paraffin by caustic potash. 

C 2 H 5 C1 + KHO = C 2 H 4 + KC1 + H 2 

Monochlorethane. Ethylene. 

Inversely, the olefines may be converted into paraffins. By com- 
bining an olefine with hydrochloric acid a monochloro-paraffin re- 
sults, which when acted on by nascent hydrogen yields a paraffin. 
C 2 H 4 + HC1 = C 2 H 5 C1 

Ethylene. Monochlorethane. 

2C 2 H 5 C1 + H 2 = 2C 2 H 6 

Monochlorethane. Ethane. 

2d. The bromine, chlorine, and iodine additive derivatives of the 
olefines are either identical or isomeric with the substitution-deriva- 
tives of the paraffins. Thus, C 2 H 4 C1 2 is either dichlorethane or ethyl- 
ene chloride ; and the additive derivatives with the acids, such as 
hydrochloric, produce mono-substitution-derivatives of the paraffins. 
In the case of the chloride, however, C 2 H 4 C1 2 , it has a different boil- 
ing-point and specific gravity according as it is prepared from ethyl- 
ene and chlorine {chloride of ethylene, alpha-dichlorethane, or the 
old "Dutch liquid"), or from monochlorethane (chloride of ethyl) 
and chlorine (chloride of monochlorethyl, beta-dichlorethane, or 
chloride of ethylidene). The former may be represented by the 
formula CH 2 CLCH 2 C1, and the latter as CH 3 .CHC1 2 . It is the 
former also which yields glycol (by reaction of the chloride with 
silver acetate, and of the resulting ethylene acetate with an alka- 
line hydrate), hence the formula of the glycol also must be 
CH 2 0H.CH 2 0H, and not CH 3 .CH(OH) 2 :— 

CILC1 CII 2 OH 

I I 

ch 2 ci cn 2 oii 

Chloride of ethylene Hydrate of ethylene 

(Dutch liquid). (glycol). 



THE ACETYLENE SERIES OF HYDROCARBONS. 

The acetylene series, C n H 2 n-a> are characterized by forming metal- 
lic substitution-derivatives. Acetylene itself, Coll.,, i^ formed during 



408 



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TERPENE HYDROCARBONS. 409 

the passage of electric sparks between carbon points in the atmo- 
sphere of hydrogen ; it is the only member which can be formed 
directly from its elements. Other members of the series are, Ailyl- 
ene, C 3 H 4 ; Crotonylene, C 4 H 6 , etc. The hydroxyl derivative of allyl- 
ene, known as propargyl alcohol, has the formula C 3 H 3 OH. 

Preparation. — Acetylene may be obtained by heating ethylene 
bromide (dibromethane) with caustic potash, and passing the gas 
into a well-cooled ammoniacal solution of cuprous chloride, with 
which it combines, forming a red precipitate, probably having the 
formula (C 2 H 3 Cu 2 ) 2 (Berthelot), called cuprous acetylide. Pure 
acetylene may be obtained from the copper compound by heating 
with hydrochloric acid. Acetylene is also formed by the incomplete 
combustion of coal gas, as when an air-gas burner is lighted below. 
It has an unpleasant odor, well known in every chemical laboratory 
in which air-gas lamps are used. 



QUESTIONS AND EXERCISES. 

691. What are the properties of ethylene, and how is it prepared? 

692. What alcohols are derived from the olefine series ? 

693. Mention the relations between'the paraffins and olefines. 

694. Give three methods of preparing acetylene. 



THE TERPENE SERIES OF HYDROCARBONS. 

T ha terpene series have the following general formula: C n H 2a _ 4 . 
Valyleni, C 5 II 6 , is the lowest, and Terebenthene, C 10 H 16 , or pure oil 
of turpentine, the most common member of the series. 

The hydrocarbons, called terpenes, C 10 H ]6 , are very commonly 
met with in analyzing the volatile oils. Very few of these oils 
have been artificially produced. Their fragrance appears to be due 
to the non-terpenoid constituent (Wallach). They differ from one 
another in the power of deviating a ray of polarized light to the 
right or left. They may be divided into two classes: (a) Terpenes, 
boiling at about 150° C, and found in the ordinary turpentine oils , 
and (6) Citrenes (limonenes), boiling at about 177° C. and derived 
from the different species of citrus. 

Oil of Turpentine (Oleum Terebinthince, U. S. P.). — Turpentine 
itself is really an oleo-resin of about the consistence of fresh honey. 
It flows naturally or by incision from the wood of most coniferous 
trees; larch (Larix Europa) yielding Venice turpentine, Abies bal- 
samea furnishing Canadian Turpentine or Canada Balsam ('Tere- 
binth \ina Canadensis, U. S. P.), the bark of Tistachia terebinthus 
the variety termed CJiian Turpentine (containing about 1 part o( 
essential oil to 7 of resin), and the Firms Austral is (palustris). P. 
allies, P. pinaster, and P. tceda affording the common American 
Turpentine (Terebinlhina, U. S. P.). Tinus niarit'uua gives the 
French or Bordeaux Turpentine, and P. picea the old fragrant 
Strasburg Turpentine. By distillation with steam this crude tur- 



410 ORGANIC CHEMISTRY. 

pentine is separated into colophony, rosin, which remains in the 
still, and essential oil of turpentine, often termed simply turpentine, 
spirit of turpentine, or " turps,'' which distils over. Mixed with 
alkali to saturate resinous acids, and redistilled in a current of 
steam, oil of turpentine furnishes about 80 per cent, of rectified oil 
of turpentine. Pinus sylvestris and P. Ledebourii furnish Russian 
Turpentine, "which, according to Tilden, consists of two turpenes 
and cymene, and also (AVallach) a laevogyre limonene. This tur- 
pentine is probably a by-product in the preparation of common 
■wood tar (Pix Liquida, U. S. P.) ; its odor is very pleasant, quite 
different from that of ordinary turpentine. The leaves of the Pinus 
sylvestris, or Scotch fir, are in Germany broken down to a woolly 
condition, producing Pine Wool or Fir Wool, or wadding used in 
making vermin-repelling blankets ; and this substance — or, still 
better, the fresh leaf — by distillation with water yields Fir- Wool 
Oil {Oleum Pini Sylvestris, B. P.), consisting, according to Tilden, 
of two turpenes, like those of Russian turpentine, and cymene. 
This oil, diffused through water by aid of magnesia, forms the 
Vapor Olei Pini Sylvestris, B. P. The terpene of Bordeaux tur- 
pentine (terebenthene) rotates a ray of polarized light more than, 
and in the opposite direction to, the terpene of American tur- 
pentine. 

Turpentine " commences to boil at about 320° F. (160° C), and 
almost entirely distils below 356° F. (180° C), little or no residue 
remaining, 1 ' whereas petroleum spirit, with which turpentine might 
be mixed, covers much wider limits of temperature during its dis- 
tillation. Petroleum spirit also, when the small round flame of the 
end of a piece of twine is brought near to some of the spirit in a 
cup, gives a momentary flash of flame at a much lower temperature 
than that at which turpentine flashes. Thus tested in the specially 
arranged flashing apparatus of the Petroleum Act, Mr. Boverton 
Redwood found that the flashing-point of turpentine was lowered 10 
degrees Fahrenheit by 1 per cent, of petroleum spirit. The spe- 
cific gravity of oil of turpentine is from about 0.855 to 0.870. 

Under the influence of heat and sulphuric acid or other chemical 
agents pure oil of turpentine (C 10 H 16 ) yields many derivatives of 
considerable chemical interest. Amongst them are two optically 
inactive terpene isomers named terebene and colophene, used for inha- 
lation and as disinfectants and deodorizers. When acted on by 
gaseous hydrochloric acid, the product is a white crystalline mono- 
hydrochloride, C 20 H, 6 HC1. Bromine acts violently on turpentine 
and terpenes, resulting in dibromides which yield cymene when 
heated. 

CUI 1K Br, = G lft H ld + 2HBp. 



Volatile Oils. 

Most of the Volatile or Essential Oils contain terpenes, the con- 
stitution of which are at present but imperfectly known. The oils 
exist in various parts of plants — at first, probably, as mere combina- 
tions of carbon and hydrogen ; but such hydrocarbons are prone to 






VOLATILE OILS. 411 

change when in contact with oxygen or moisture ; hence these 
liquids, even when freshly obtained from the plants, and more 
especially as they occur in pharmacy, are usually mixtures of the 
liquid hydrocarbons or elccoptens (from e?iaiov, elaion, oil, and b-nrofiai, 
optomai, I see) with oxidized hydrocarbons, which are commonly 
solid or camphor-like bodies termed stearoptens (from creap, stear, 
suet), and which on cooling often crystallize out ; or on distilling an 
oil the stearopten may remain in the retort, being less volatile 
than the elseopten. Volatile oils should, obviously, be preserved in 
well-closed bottles. Oxidation also proceeds more slowly in a cold 
than in a warm temperature. The oils are also often associated 
with further oxidized bodies termed resins. Of the hydrocarbons, 
those most commonly occurring are identical with, or are isomers 
of, that from oil of turpentine, and these terpenes are easily con- 
verted into their polymers, Ci 5 H 24 and C 20 H 32 , by the action of heat, 
strong acids, etc. 

The process by which volatile oils are usually obtained from 
herbs, flowers, fruits, or seeds may be imitated on the small 
scale by placing the material (bruised cloves or caraways, for 
instance) in a tubulated retort, adapting the retort to a Liebig's 
condenser, and passing steam, from a Florence flask, through 
a glass tube to the bottom of the warmed retort. The steam 
in its passage through the substance will carry the particles of 
oil over the neck of the retort into the condenser, and thence, 
liquefied and cooled, into the receiving vessel, where the oil 
will be found floating on the water. It may be collected by 
running^off the distillate through a glass funnel having a stop- 
cock in the neck, or by letting the water from the condenser 
drop into an old test-tube which has a small hole in the bottom, 
or any similar tube placed in a larger vessel, the water and oil 
being subsequently run off separately from the tube as from a 
pipette. Volatile oils, like fixed oils, stain paper ; but the 
stain of the former is not permanent like that of the latter. 
Oils of lemon and orange are sometimes obtained by mere 
pressure of the rind of the fruit. 

The following official (U. S. P.) waters are made by distributing 
2 parts of volatile oil over the large surface afforded by 4 parts of 
cotton, and percolating with 1000 parts of distilled water: Aquce 
Anisi, Cinnamomi, Fceniculi, Menthce Piperita?, Menthas Viridis. 
Aqua Auraniii Florum, U. S. P., and Aqua Rosas, U. S. P., arc 
obtained by distilling 40 parts of flowers with 1200 of water. 

The presence of alcohol in an essential oil may be detected and its 
quantity estimated by shaking with an equal bulk of pure glycerin. 
The latter dissolves the alcohol, and is augmented in volume accord- 
ing to the amount of alcohol present (Boettger). (For test for alco- 
hol, see Index, -Alcohol.") 

A large number of volatile oils are employed in medicine, either 



412 ORGANIC CHEMISTRY. 

in the pure state, in the form of saturated aqueous solution (medi- 
cated water), solution of spirit of wine, 1 in 5 {Essentia Anisi and 
Essentia Menthce Piperita?, B. P.) and 1 in 50 (Spiritus Cajuputi, 
Junijieri, Lavandulce, Menthce Piper it ce, Myristicce, Rosmarini — 
B. P.), or as leading constituents in various barks, roots, leaves, etc. 
The strength of Spiritus Anisi, U. S. P., and Sp. Cinnamomi, U. S. 
P., is 10 of oil to 90 of alcohol. Sp. Menthce Piperitce, U. S. P., and 
Sp. Menth. Viridis, U. S. P., are of similar strength, but also con- 
tain whatever may be extracted by the 100 parts of the spirit from 
] part of the dried herb. Spiritus Aurantii, U. S. P., contains 6 of 
oil and 94 of alcohol ; Sp. Gaultherice, U. S. P., Sp. Junipein, U. S. P., 
Sp. Lavandulce, U. S. P., and Sp. Myristicce, U. S. P., contain 3 of 
oil and 97 of alcohol : Spiritus Limonis, U. S. P., is made with 6 of 
oil, 4 of freshly-grated lemon-peel, and alcohol sufficient to produce 
100 of filtered product. Perfumes (" scents " or " essences," includ- 
ing "Lavender-Water" and "Eau de Cologne," or "Cologne-Water, 
Perfumed Spirit or Spiritus Odoratus,'' as it is termed in U. S. P.) 
are for the most part solutions of essential oils in spirit of wine or 
spirituous infusions of materials containing essential oils. The fol- 
lowing oils are, directly or indirectly, official in the Pharmacopoeias : 
1. Volatile oil of Bitter Almond (p. 416). 2. Oil of the fruits of 
Ajwain or Omum, Cam in, Ajowan, or Ptychotis Ajowan {Fructus 
Ptychotis, P. I.), contains cymol or cijmene (C 10 H ]4 ) and a stearopten 
{Ajwain-ka-phul. flowers of ajwain) identical with thymol, C 10 H u O. 
3. Oil of Dill {Oleum Anethi, B. P.), a pale, yellow, pungent, acrid 
liquid distilled from dill-fruit ; it contains a hydrocarbon, anethene 
(C 10 H ]6 ), and an oxidized oil (C 10 H 14 O) identical with the carvol of 
oil of caraway (Gladstone). 4. Oil of Aniseed {Oleum Anisi, U. S. 
P.), a colorless or pale-yellow liquid, sp. gr. 0.976 to 0.990, of sweet- 
ish warm flavor, distilled in Europe from the Anise-fruit {Pimpinella 
anisum) {Anisum, U. S. P.), and in China from the fruit of Star- 
Anise {Illicium anisaium) {Illicium, U. S. P.) ; it is a mixture of a 
hydrocarbon isomeric with oil of turpentine and anethol, a stear- 
opten (C J0 H 12 ) which crystallizes out at low temperatures. 5. Oil 
of Chamomile {Oleum Anthemidis, B. P.), a bluish, or, when old, 
yellow oil, of characteristic odor and taste, distilled from chamomile 
flower-heads {Anthemis, IT. S. P.). The official variety {Anthemis 
nobilis) yields about 0.2 per cent, of an oil composed of a hydro- 
carbon (C ]0 H 16 ) and an oxidized portion (Cj H 16 O 2 ), which, heated 
with potash, gives angelate of potassium (KC 5 II 7 2 ), whence is ob- 
tained angelic acid (HC 5 H 7 2 ). According to Demarcay, Kopp, and 
Kobig, the oil is a mixture of the angelates of butyl and amyl and 
similar bodies. The flower-heads of another variety, Matricaria 
chamomilla {Matricaria, U. S. P.), contain a stearopten (C 10 H :fi O) 
having the composition of laurel-camphor. 6. Oil of Horseradish- 
root {Armoracice Radix, B. P.) is, according to Ilofmann, the sulpho- 
cyanate of butyl or tetryl (C 4 H 9 CNS) ; it is the chief active ingre- 
dient of Spiritus Armorarice Composilus, B. P. 7. Oil of Sweet- 
Orange peel {Aurantii Dulcis Cortex, U. S. P.) and Oil of Bitter- 
Orange rind {Aurantii Amari Cortex, B. P. ; Oleum Aurantii 
Corticis, U. S. P.), the former the flavoring constituent of the 









VOLATILE OILS. 413 

official syrup of the peel (Syrupus Aurantii, U. S. P.), and the oils 
of various species of Citrus — namely, 8, lemon ( Oleum Limonis, U. 
S. P.), from Lemon Peel (Limonis Cortex, U. S. P.) ; 9, lime ; 10, 
bergamot (Oleum Bergamii, U. S. P.); 11, citron, and a variety of 
citron termed cedra — resemble each other in composition, all con- 
taining hesperidene, a hydrocarbon (C 15 H 24 ), and a small quantity of 
oxidized hydrocarbons (C 10 H ]0 O 5 ,C 15 H 10 O), and (Wright and Piesse) 
(C 20 H 30 O 3 ), etc. Tilden states that lemon oil, distilled from the fresh 
peel, consists chiefly of a terpene (C 10 H 16 ), boiling at 176° C, with 
small quantities of a terpene boiling below 160° and a hydrous 
terpene ; the odor of the oil being due to the mixture. Expressed 
lime-essence also contains a soft resin. 12. Oleum Aurantii Florum, 
U. S. P., Oil of Neroli, or Orange- Flower (Aurantii, Flores, U. S. P.), 
the aqueous solution of Avhich is official in the forms of water (Aqua 
Aurantii. Florum, U. S. P.) and syrup (Syrupus Aurantii Florum y 
B. P. and U. S. P.), contains a fragrant hydrocarbon (C 10 H ]6 ), color- 
less when fresh, but becoming red on exposure to light, and an in- 
odorous oxidized hydrocarbon. Strong acids, especially nitric, attack 
the oil in orange-flower water, coloring the fluid of a rose tint. 13. 
Oil of Petit Grain, distilled from the leaves and shoots of the orange 
tree, consists chiefly of a hydrocarbon apparently identical with that 
of oil of neroli. 1 4. The leaves of Boldo ( Peumus Boldus), a Chilian 
shrub (tonic and hepatic), yield 2 per cent, of essential oil (and ac- 
cording to Bourgon and Verne, an alkaloid, boldine). 15. Oil of 
Buchu-leaves (Buchu, U. S. P.) consists chiefly of a fluid oil, C 10 H 18 O, 
holding in solution a crystalline stearopten, diosphenol, C U H 22 3 
(Fllickiger ; C, IT 16 O 2 , Spica, Shimoyana also). 16. Oil of Cannabis 
indica, (see page — ). 17. Oil of (the lesser) Cardamoms, from the 
seeds of the capsules (Cardamomum, U. S. P.), is chiefly a hydro- 
carbon (C 10 H 16 ) isomeric with oil of turpentine (terpilcne and prob- 
ably limonine) and a camphor resembling turpentine-camphor 
(C,oH 16 3H 2 0). 18. Oil of Cqjuput (Oleum Cajuputi, U. S. P.) is a 
mobile bluish liquid, consisting chiefly of hydrous cajuputene or 
cajuputol (C 10 H 16 ,H 2 O). The latter, repeatedly distilled from phos- 
phoric anhydride, yields cajuputene itself (C ]0 H 16 ), which has the 
odor of hyacinths. Fresh cajuput-oil has a green hue, which is 
perhaps transient, for the color of the oil of trade is due to copper 
(Guibourt and Heisted) : certainly the green coloring-matter of pure 
cajuput-oil is organic, and probably chlorophylloid. 19. Oil of Car- 
aivay-frmt (Caruin, U. S. P., Oleum Carui, B. P., Oleum cari, U. S. 
P.) is a mixture of carvene (C 15 H 2 J and carrot (C 10 lI u O). 20. Oil oi' 
Cloves [Caryophyllus, U. S. P., Oleum caryophylli, U. S. P.) and oi' 
Pimento or Pimcnia, U. S. P. or Allspice (Oleum Pimentce, U, S. IM, 
both heavier than water, contain a liquid hydrocarbon (C 15 H 2i ), 
eugrnol (C 10 H 12 O 2 ) a solid body, eugenin, isomeric with the eugenic 
acid, a second crystalline substance, earyophyllin (O 10 ll u; O). isomeric 
Avith common camphor, and a salicylic compound. 21. Oil of (\is- 
Carilla-boxln (( y ascari//<(< V. S. P.) has not been fully examined. 22. 
Oil of Cinnamon-bsbvk (Cinnamcmum, V. S, P.) and of Cassia-bark 
is mostly cinnamic aldehyde (C 8 H,COH). Boiled with nitric acid, 
it furnishes benzoic aldehyde (C 6 H 6 COH) and benzoic acid (C 6 H - 



414 ORGANIC CHEMISTRY. 

COOH) •, with chloride of lime it yields benzoate of calcium (C 6 H 5 - 
COO) 2 Ca ; and with caustic potash gives cinnamate of potassium 
(C 8 H 7 COOK). The specific gravity of oil of Ceylon cinnamon is 
about 1.040, and of Chinese cinnamon (oil of cassia) about 1.060. 
Both are termed Oleum Cinnamomi in U. S. P. 23. Oil of Citronella, 
a grass oil, from Andropogon nardus, is chiefly composed of citronellol 
(C 10 H ]6 O and C 10 lI lfe O, Wright), probably isomeric with the absinthol 
from the Artemisce absinthium or wormwood {Absinthium, U. S. P.) 
(Gladstone). Kremer also obtains heptoic aldehyde (C 7 H 14 0), a 
terpene (C 10 H 16 ), etc. 24. Oil of Copaiva (Oleum Copaibce, U. IS. P.) 
and, 25. of Cubebs (Oleum Cubebce, U. S. P.) are hydrocarbons hav- 
ing the formula C 15 H 24 . This cubebene is sometimes associated with 
a camphor, hydrous cubebene (C 15 H 24 ,II 2 0). Oil of cubebs also con- 
tains a small quantity of a terpene (C 10 H 16 ). 26. Oil of Coriander 
(Coriandrum, U. S. P.; Oleum Coriandri, B. P.) seems to have the 
composition of hydrous oil of turpentine (C ]0 H ]6 H 2 O). 27. The fruits 
of Cumin or Cummin. (Cuminum cyminum), an ingredient of many 
curry-powders, contains about 3 per cent., and those of Water Hem- 
lock or Coicbane (Cicuta virosa) about \\ per cent., of an essential 
oil composed of cymol or cymene (C 10 H 14 ) and cumic aldehyde (C 9 TI n - 
COII). The latter is an aldehyde readily uniting with alkaline 
bisulphites and by oxidation yielding cuminic acid (C 9 H n COOII). 
Cymol also occurs in Garden Thyme (Thymus vulgaris). '27a. The 
fresh flowering herb of Erigeron canadense, or Canadian Fleabane, 
yields an essential oil (Oleum Erigerontis, U. S. P.) 28. Eucalyptus 
globulus leaves (Eucalyptus, U. S. P.) furnish nearly 1 per cent, of 
eucalyptol, an oil (Oleum Eucalypti, U. S. P.) of sp. gr. 0.917, the 
more volatile and chief portion of which is cymene, and a terpene 
(C 10 H 14 -j- 2C 10 H 16 ), together with an oxidized portion, C ]0 H 14 O and 
C ]0 H 1(i O, and an oil having the same composition as cajuputol and of 
the chief constituent of ivormseed oil, C 10 H lfe O or C 10 H 16 .H 2 O. Dif- 
ferent species of eucalyptus may yield oils differing in specific gravity, 
flavor, and odor. Like the turpentines they are good solvents of 
resins. Yoiry states that eucalyptol is present also in the oil of Lav- 
andula spica, oil of spike or " foreign " oil of lavender. 29. Elecam- 
pane-root, Inula Helen/ inn (Inula, U. S. P.), by distillation with 
water yields solid volatile helenin (C 6 H & 0), a camphor oil or inulol 
(C 10 H 16 O), and inulic anhydride (C 15 H 2 ,0 8 ), as well as, according 
to Marpmann, crystals of alantic acid (C 15 H 22 3 ) and fluid alantol 
(C 20 H 32 O), each more powerfu-ly antiseptic than helenin. 30. Oleum 
Fceniculi, U. S. P., Oil of Fennel-fruit (Foeniculum, U. S. P.) differs 
in odor, but contains the same proximate constituents as oil of anise. 
31. Oil of Geranium, or Ginger Grass oil, from Andropogon schoe- 
nanthus and various species of Pelargonium, contains geraniol 
(C 10 H ls O). Oil of Hedeoma or American Pennyroyal ( Oleum Hedeomce, 
U. S. P.) has a sp. gr. of about 0.940. It yields kedeomol (C 10 H 18 O), 
isoheptoic acid (C 7 I1 13 2 ), and other substances (Kremer). 32. Grains 
of Paradise (Amomum melegueta), Guinea Grains or Melea'ueta Pep- 
per. Semina Cardamomi Majoris, contain an essential oil (C ]0 H 16 and 
C 10 H ]6 O) and a highly pungent resin. 33. Oil of Juniper (Oleum 
Juniperi, U. S. P.). the active constituent of Juniper Tops and Ber- 



VOLATILE OILS. 415 

ries {Juniperus, U. S. P.), contains a hydrocarbon (C 10 Hi 6 ) which by 
contact with water yields a white crystalline hydrous compound 
(C 10 H 16 ,H 2 O) and a polymeric hydrocarbon (C 20 H 32 ). 34. Oil of 
Lavender {Oleum Lavandula, U. S. P.), from the flowering tops or 
whole herb, and Oleum Lavandulae Florum, U. S. P., from the flow- 
ers, of Lavandula vera {Lavandula, U. S. P.), have not been satis- 
factorily examined. 34a. Oil of Myrcia {Oleum Myrcia, U. S. P.), 
oil of bay or bayberry oil (sp. gr. about 1.040), is obtained from 
the leaves of Myrcia acris. 35. Oil or butter or camphor of Orris 
{Iris fiorentina) is a soft solid lighter than water. Fliickiger and 
Hanbury found it to be chiefly myristic acid associated with a little 
essential oil. 36. Oil of Peppermint {Oleum Mentha Piperita, U. 
S. P.) consists of a hydrocarbon, menthene (C ]0 H ]8 ), different from 
that of most volatile oils, and hydrous menthene (C 10 H 18 ,H 2 O), men- 
thol, a crystalline stearopten. 37. Oil of Spearmint {Oleum Mentha 
Viridis, U. S. P.), the Common Mint of the kitchen-garden, contains 
a liquid having the formula C 10 H 20 O or C 10 H 18 ,H 2 O; also, according 
to Gladstone, an oil (C 10 H u O), isomeric with carvol. 38. Oil of 
Pennyroyal {Mentha pulegium) contains, according to Kane, C ]0 H 16 O. 
38a. The leaves and tops of Melissa officinalis or Balm {Melissa, 
U. S. P.), yield a volatile oil containing a camphor. 39. Oil of Nut- 
meg {Oleum Myristica, B. P. and U. S. P.), and of the arillus of the 
nutmeg or mace {Macis, U. S. P.), is composed of a hydrocarbon, 
myristicene (C 10 H 16 ) and myristicol (C 10 II 16 O) (Gladstone). 39a. Oil 
of Origanum, from Origanum vulgare, or Wild Marjoram {Origa- 
num,'V. S. P.), is of a bright yellow, and has an odor somewhat like 
peppermint ; it is a mixture of a liquid hydrocarbon and a camphor 
which is deposited after long standing. 40. Oil or Otto or Attar of 
Cabbage-Pose Petals {Rosa Centifolia, U. S. P. ; Oleum Rosa, U. S. 
P.) gives the fragrance to rose-water {Aqua Rosa, B. P.). It resem- 
bles most other volatile oils in being composed of a hydrocarbon ansl 
an oxidized portion, but differs from all in this respect, that the hydro ■ 
carbon is solid and is destitute of odor, while the oxygenated con- 
stituent is liquid and the source of the perfume. According to 
Fliickiger, the solid hydrocarbon (C 18 H 16 ) yields succinic acid as the 
chief product of its oxidarton by nitric acid, and in other respects 
affords evidence of belonging to the paraffin series of fats. 41. Ros- 
marinus, U. S. P., Oil of Rosemary-tops {Oleum Rosmarini, U. S. P.), 
exists in the plant to the extent of from H to 3 parts per 1000. It 
chiefly consists of a hydrocarbon (C 10 H 16 ) resembling that from 
Myrtle, Myrtus communis, but also contains camphor, borneol, and 
cyneol (O 10 lT 18 O) in variable proportions. 4 , _ > . Oil of Rue {Oleum 
Rutce, U. 8. I'.) contains a small quantity of hydrocarbon (C 10 H 16 ), 
with some rutic aldehyde (C 10 H 20 O), but, according to Greville Wil- 
liams, is chiefly euodic aldehyde (O n H 22 0), some lauric aldehyde 
(C 12 ,H 24 0) also being present, Gorup-Besanez and Grimm have 
obtained oil of rue (C n H 22 0) artificially as one of the products of 
the destructive distillation of acetate and caprate of calcium. 13. 
Oil of Sage {Salvia, U. S. P.) contains about 40 per cent, of salviol, 
C ]0 H ]6 O ; about 'JO per cent, of two 1() H 16 hydrocarbons boiling at 
l?)(\° and l- r >7 Q Q, respectively; about 10 per cent, of a camphor, 



416 ORGANIC CHEMISTRY. 

C ]0 H 16 O ; and about 10 per cent, of eedrene, C 15 H 24 (Muir). 44. Oil 
of Savin (Oleum Sabince, U. S. P.), obtained from the tops of Juni- 
perus Sabina or Savine (Sabina, U. S. P.), contains several hydro- 
carbons, but none isomeric with oil of turpentine (Tilden). 45. 
Oil of Elder-flowers (Sambucus, U. S. P.) occurs in very small quan- 
tity ; it has a butyraceous consistence ; it contains a hydrocarbon, 
sambucene (C ]0 H 16 ), and probably a camphor. 46. Oil of Sandal- 
wood (Oleum Santali, U. S. P.), or oil of santal, is composed (Cha- 
poteaut) of two bodies ; mostly of a substance having the formula 
C 15 H 24 (boiling at 572° F.), and a small quantity of a substance 
having the formula C 15 H 26 (boiling at 600° F.). It occurs to the 
extent of about 1 per cent, in the fragrant white or yellow sandal- 
wood of India, Santalum album, a small tree of the natural order 
Santalaceae, and not to be confounded with the Pterocarpus Santa- 
Unus, a tree of the natural order Leguminosae, and furnishing the 
inodorous Red Sandal-wood or Red Sanders Wood of the dyer. 
47. Oil of Sassafras-root (Oleum Sassafras, U. S. P.) (Sassafras, 
U. S. P.), sp. gr. 1.094, contains nine-tenths of its weight of Safrol 
or Sassafrol, C 10 H 10 O 2 , also a small quantity of a terpene. Sassafras 
camphor, C 10 H 10 O 2 , is deposited when the oil i,s exposed to low tem- 
perature. 48. Oil of Mustard (Oleum Sinapis Volatile, U. S. P.) is 
sulphocyanate of allyl (see Index). If contaminated with alcohol 
its sp. gr. is below 1.015. 49. Oil of Sweet Flag (Acorus calamus) 
contains the hydrocarbon (C 10 H 16 ). The rhizome (Calamus, U. S. 
P.) also contains Acorin, C S6 H 60 O 6 , a bitter glucoside, and an alka- 
loid, calamine. 50. The tops and leaves of Thuja occidentalis, or 
Arbor vitce (Thuja, U. S. P.), yields two oxygenated oils, also a bitter 
principle (penipicrin). 51. Oil of common garden Thyme (Thymus 
vulgaris, Oleum Thijmi, U. S. P.) is composed of cymene or cymol 
(C 10 II 14 ), thymene (C; o II 16 ), and thymol (C 10 H u O) (Thymol, U. S. P.). 
Thymol crystallizes out when oil of thyme or of ptychotis, etc. is 
kept at a low temperature for a day or two. It may also be ob- 
tained by shaking the oils with caustic alkali, and treating the sep- 
arated alkaline liquid with an acid. It may be purified by distillation 
or by crystallization from alcohol. It would seem that as an antiseptic 
thymol is far stronger than carbolic acid. Thymol is also contained 
in oil of Horsemint(Monarda). 52. Oil of Turmeric (Curcuma longa) 
is said by Jackson and Menke to be chiefly an alcohol having the 
formula C 19 H 27 OH. They name it turmerol. It is a light-yellow 
volatile oil, having the sp. gr. 0.902. It is to this oil that turmeric 
(hence curry powder, partly) owes its flavor and odor. 53. Oil of 
Valerian-root (Valeriana, U. S. P., Oleum Valeriana?, U. S. P.) is a 
mixture of a hydrocarbon, valerene or borneene (C 10 H ]6 ), and valerol 
(C 6 H 10 O). Valerol slowly oxidizes to valerianic acid, known by its 
smell. A similar change occurs at once if oil of valerian be allowed 
to fall drop by drop on heated caustic potash : C 6 H 10 O + 3KHO + 
H 2 = K 2 CO :i + C 4 H 9 COOK + 3H 2 . By the action of sulphuricacid 
on the valerianate of potassium thus produced valerianic acid is 
obtained. 54. Oil of Verbena, Lemon Grass Oil, or Indian Melissa 
Oil. is obtained from Andropogon citralus (Oleum Andropogi Ciirati, 
P. I.). 55. Oil of Ginger (Zingiber, B. P.) is, according to Thresh, 



CAMPHORS. 417 

a complex mixture of hydrocarbons and their oxidation-products. 
Cymene (C 10 H ]4 ) is present, a terpene, aldehydes, and ethereal salts. 
(For an analysis of ginger, by Thresh, and for papers on " Soluble 
Essence of Ginger," see the Pharmaceutical Journals for August 30 
and September 6, 1879, and March 4, 1882.) 56. American Worm- 
seed [Chenopodium, U. S. P.) contains a volatile oil (Oleum Cheno- 
podii, U. S. P.). 

Caoutchouc, or India-rubber, and Gutta-Percha. 

Caoutchouc is the hardened juice of Dichopsis Gutta, Hevea 
(Sijyhonia) Brasiliensis, Castilloa elastica, Vrceola elastica, Ficus 
elastica, and other plants. Heated moderately with sulphur, it 
takes up 2 or 3 per cent., and forms vulcanized india-rubber ; at 
a higher temperature a hard, horny product termed ebonite or vul- 
canite results. Gutta-Percha (Gutta-Percha, U. S. P.) is the con- 
crete drop or juice of the percha (Malay) tree, the Isonandra gutta, 
and of other Sapotaceous plants. White gutta-percha is obtained 
by precipitating a solution of ordinary gutta-percha in chloroform 
(Liquor Gutta-percha, U. S. P.) by alcohol, washing the precipitate 
Avith alcohol, and iinally boiling in water and moulding into the 
desired form while still hot. The British solution of gutta-percha 
(Liquor Gutta-Percha, B. P.) is made by digesting thin slices of 
gutta-percha in 12 parts by weight of chloroform, and then " fining " 
by shaking with one part of carbonate of lead and setting aside till 
the fluid is clear. 

These two elastic substances, in the pure state, are hydrocarbons 
(.rC 5 TI 4 ), usually slightly oxidized. When caoutchouc is distilled, a 
terpene, jC 10 Hi 6 , called caoutchin, is obtained. 

Camphors. 

In addition to the stearoptens or camphors already mentioned as 
being contained in or formed from volatile oils, there is one that is- 
a common article of trade. It is obtained from the wood of Ciniia- 
momum camphora or Camphor-laurel, in Japan (termed, in Europe, 
"Dutch camphor," because imported by the Dutch) and in China 
(known as Formosa camphor) by a rough process of distillation 
with water, and is purified by resublimation (Camphora, U. S. P.). 
The formula of laurel-camphor is C 10 II lfi O. Sp. gr. 0.000 to 0.00.") : 
melting-point, 175° C. ; boiling-point, 205° C. Bromine heated with 
camphor gives monobrom-camphor (C 10 II K) BrO) and hydrobromie acid. 
Monobrom-camphor is camphor in each molecule of which an atom 
of hydrogen has been displaced by one of bromine. Recrystallized, 
it occurs in white prisms. The essential oil, from which doubtless 
camphor is derived by oxidation, is easily obtained from the wood, 
and is occasionally met with in commerce under the name ol' liquid 
camphor or camphor-oil. It contains hydrocarbons resembling tere- 
binthene and citrene, and camphor hydrate, C 10 H ]6 O,H 2 O, as well as 
camphor. By exposure to air it becomes oxidized and deposits com 
moii camphor, 2C 20 H 32 O I O, 4C 10 ll I( .O. Camphor distilled with 
phosphoric anhydride yields rvinol, C,,, I',,. There is another kind 



418 ORGANIC CHEMISTRY. 

of camphor, borneol, in European markets, less common than laurel- 
camphor, but highly esteemed by the Chinese: it is obtained from 
the Dryobalanops aromatica, and denominated Sumatra or Borneo 
camphor. It differs slightly from laurel-camphor in containing 
more hydrogen, its formula being C 10 H ]8 O. It may be obtained 
by acting on camphor with hydrogen, the camphor being dissolved 
in some inert liquid such as toluene, and sodium added : the sodium 
forms a compound, C 10 H 15 OXa, while the hydrogen thus liberated 
acts on another portion of the camphor, forming borneol, C ]0 H 17 (OH) 
— a better result being obtained if absolute alcohol is used instead 
of toluene (Jackson and Menke). It is accompanied in the tree by 
a volatile oil (C 10 H 16 ) isomeric with oil of turpentine. This oil, bor- 
neeiie, is also occasionally met with in trade under the name of liquid 
camphor or camphor oil, but differs from laurel-camphor oil in not 
depositing crystals on exposure to air. 

The constitution of camphor is still doubtful. Camphor is sol- 
uble to a slight extent in water (40 grains per gallon, Pooley). The 
official Camphor-Water {Aqua Camphorce, U. S. P.) is such a 
solution. 

Common camphor, and many others of the camphors, oily hy- 
drocarbons, and oxidized hydrocarbons, yield camphoric acid, 
C 8 H 14 (COOH) 2 , and camphoronic acid, C 7 H 9 (OH)(COOH) 2 , when 
attacked by oxidizing agents. Such reactions indicate natural 
relationships. Camphoric acid is a good antiseptic. 

Cantharidin (C ]0 H 12 O 4 ), the active blistering principle of cantha- 
rides (Cantharis, U. S. P.) and other vesicating insects (such as 
Mylatris cichorii or Telini Fly,V. I., common in India), has most 
of the properties of a camphor or a stearopten. It slowly crystal- 
lizes from an alcoholic tincture of the beetles in fusible, volatile, 
micaceous plates. The following process for the extraction of can- 
tharidin is by Fumouze : Powdered cantharides are macerated with 
chloroform for twenty-four hours ; and this treatment is repeated 
twice with fresh quantities of solvent, the residue having been well 
squeezed each time. The collected solutions are then distilled, and 
the dark-green residue treated with bisulphide of carbon, which dis- 
solves fatty, resinous, and other matters, and precipitates the can- 
tharidin. The precipitate is placed on a filter, washed with bisul- 
phide of carbon, and recrystallized from chloroform. The same 
process, omitting the final recrystallization, may be used for the 
quantitative estimation of cantharidin in cantharides. The average 
quantity found is from four to five, or occasionally ten or even 
twelve, parts in one thousand. Cantharidin is readily soluble in 
warm glacial acetic acid (Tichborne), and still more readily in 
acetic ether or chloroform. Cantharides from which the fat has 
been removed by petroleum ether yield their cantharidin with 
great facility. 

Massing and Dragendorff consider cantharidin to be an anhy- 
dride, and that with the elements of water it forms cantharidic acid 
(H 2 C 10 H 12 O 5 ). Piccard gives the vapor density of cantharidin as 
about 6.5, and its formula C 10 H 12 Q 4 . Homolka assigns to it the 
formula C s H 13 2 .CO.COOH. 



RESISTS. 419 

Resins, Oleo-Resins, Gum-Resins. 

Resins seem to be the oxidized products of terpenes and the 
allied hydrocarbons ; they occur in plants, generally in association 
with volatile oils. They closely resemble camphors and stearoptens, 
but are not volatile, and differ from oils and fats mainly in being solid 
and brittle. For convenience they are classified as resins, oleo-resins, 
and gum-resins, the distinctions being founded as much on physical 
as on chemical properties. 

Oleo-resins are mixtures of a resin and a volatile oil. 

Gum-resins are mixtures of a resin or oleo-resin and gum. 

Balsams are commonly described as resins or oleo-resins which 
yield benzoic and cinnamic acids ; they are Benzoin (Benzoinum, 
U. S. P.), Balsam of Peru (Balsamum Peruvianum, U. S. P.), Bal- 
sam of Tolu (Balsamum Tolutanum, U. S. P.), and Storax, and are 
treated of under the respective acids. 

Some oleo-resins, containing neither of the above acids, are often 
termed balsams (e. g. Balsam of Copaiva and Canada Balsam) ; these 
will be treated under the head of Oleo-resins. 

A physico-chemical method for the identification of the chief 
resins, gum-resins, and balsams will be found in the Pharmaceutical 
Journal for November 17, 1877. 

Resins appear to be somewhat antiseptic. Beer is said never to 
turn sour in casks lined with Burgundy pitch. The resin of hops 
has perhaps a similar effect in retarding oxidation of alcohol. 

Resins.* — 1. Resin, rosin, or colophony (Resina, U. S. P.) is the 
type of this class. Its source is the oleo-resin or true turpentine of 
the conifers, a body which by distillation yields spirit of turpentine 
and a residuum of rosin. "Brown" and "White" rosin are met 
with in trade. The former is the residue of American, the latter of 
Bordeaux, turpentine (from Pinus Abies, etc. and Pinus Maritima 
respectively). The chief constituents of brown resin are pinic acid 
(IIO 20 H 29 O 2 ) an( l sylvic acid, identical in composition, but differing 
in properties [vide Isomerism), the former being soluble and the 
latter insoluble in cold spirit of wine. White resin or " galipot" is 
chiefly primaric acid, also isomeric with pinic acid. Pinic acid 
cautiously heated yields colophonic or colopholic acid. Rosin, by 
destructive distillation, yields resin oil, the first portion being 
"pale," the next "blue," and the third "green resin oil." Mixed 
with other oils, they are used for lubricating purposes and in the 
manufacture of printing ink. Among the products of the destruc- 
tive distillation of resin Tichbornc has found "colophonic. hydrate" 
(0 10 lI 22 O 3 ,lI 2 O), a white inodorous crystalline substance, and by 
depriving this of water has obtained white crystalline colophonine 
(C I0 II 22 O 3 ). Resin is soluble in oil of turpentine. Contact with 
sulphuric acid immediately colors it strongly red. It is a constit- 
uent of eight of the fourteen plasters {Emplastra) of the British 
Pharmacopoeia. 2. Amicin (C 20 H 80 O 4 ), the chief acrid and one of 



* The student is not expected to remember, but to understand, all 
that follows respecting the resins. (See page ix of Preface. I 



420 ORGANIC CHEMISTRY. 

the active principles of Arnica (Amicce Flores, U. S. P.; Arnicce 
Rhizoma, B. P.), is a resin, and probably a glucoside. 3. Cannabin, 
said to be the active principle of Indian Hemp or Indian Cannabis 
{Cannabis Indica, U. S. P., the flowering tops of the female plant of 
Cannabis Sativa) and American Cannabis {Cannabis Americana, U. S. 
P., the Cannabis Sativa plant grown in the United States), was ob- 
tained in 1846 by T. and H. Smith, and is a resin. Personne in 1857 
isolated a volatile, oil, also said to possess much medicinal activity, con- 
sisting of cannabene (C 18 H 20 ) and a solid crystalline " hydride of can- 
nabene " (C 18 H 22 ). Preobrasehensky has stated, and since re-asserted, 
that the active principle is nicotine. Kenned} 7 searched for nicotine 
by two methods, but found none. Hay found an alkaloid, tetano-can- 
nabin. Warden and Waddell, after careful investigations, consider 
that the active principle of the plant has yet to be isolated. Jahns 
finds choline present. 4. Capsicum-fruit contains a resin (p. 504). 
5. Castorin, a resinous matter, is the name given to the chief con- 
stituent of Castor {Castoreum, B. P.), the dried preputial follicles 
and included secretion of the beaver {Castor Fiber). 6. Copal. — 
The best copal is the exuded resin of trees of extinct forests, and is 
found beneath the surface of the ground in the neighborhood of 
existing trees. It appears to be a mixture of acids, but its charac- 
ter is still obscure. 6a. Doundahe-bark, an African febrifuge, from 
Sarcocephalus esculentus, owes its activity to resinoid substances, 
according to Heckel and Schlagdenhauffen. 7. Dragon's Blood, a 
crimson-red resin found as an exudation on the mature fruits of a 
Rotang or Rattan Palm {Calamus draco). It consists of resins 
having the probable formula C 20 H 24 O 4 and C 20 II 21 O 4 (Johnstone). 
8. Erqotin is a very active resinoid constituent of Ergot {Ergota, 
U. S. I\), or the sclerotium (compact mycelium or spawn) of Clav- 
iceps purpurea, produced within the pales and replacing the grain 
of the common rye, Secale cereale. Maize or Indian Corn, Zea 
mays, appears to foster a similar parasite, the Ustilago maydis, or 
Corn Smut {Ustilago, U. S. P.). According to "Wenzell, ergot con- 
tains two alkaloids, ecboline and ergotine, to the former of which, he 
says, the activity of ergot is due. Blumberg considers these alka- 
loids to be identical. Tanret states than an unstable alkaloid termed 
ergotinine occurs in ergot to the extent of 1 per 1000, and that it is 
accompanied by camphor ; also ergosterin, C 26 H 40 OH 2 O, resembling 
cholesterin. Dragendorflf and Poclwissotzki assert that ergot owes 
most of its activity to sclerotic or sclcrotinic acid, present to the 
extent of about 4 "per cent. Recent investigations seem to show 
that cornutine is an active alkaloid of ergot, associated with ergot- 
inic and sphacelenic acids, picrosclerotine and ergotinine. The activ- 
itv really seems to be due to a combination of alkaloids^ and acids, 
and not "to any one constituent, as no principle representing the full 
activity of ergot has been extracted. The same may be said of a 
similar therapeutical agent, the root-bark of Gossypium herbaceum 
{Gossypii Radicis Cortex, U. S. P.), the activity of which appears to 
reside in a red resin. Ergot also contains choline, which by 
decomposition may yield trimethylamine. " Ergotin" {Ergotiuum, 
B. P.) is an alcoholic extract of an aqueous extract of ergot. 9. 



RESINS. 421 

Guaiacum-resin is a mixture of substances (see Index). 10. Jalap- 
resin (see Index). 11. Kousso or Kooso {Brayera, U. S. P.) yields 
yellow crystals of a resinoid body readily soluble in alkaline liquids, 
kosin or koussin (C 31 H 38 O 10 ). It is, perhaps, an anhydride. 12. 
Mastic (Mastiche, U. S. P.) is a resinous exudation obtained by 
incision from the stem of the Mastic or Lentisk tree. Nearly nine- 
tenths of mastic is mastichic acid (C 20 H 31 O 2 ), a resin soluble in alco- 
hol 5 the remainder consists of masticin (C 20 H 31 O), a tenacious elas- 
tic resin and a terpene having the formula C 10 H 16 . 13. Mezereon 
{Mezereum, U. S. P.), the dried bark of Daphne mezereum, Mezereon, 
and Daphne laureola, Spurge Laurel, owes its acridity to a resin. 
14. Pepper contains resin (see Index). 15. Burgundy pitch {Pix 
Burgundica, U. S. P.) is the melted and strained exudation from the 
stem of the Spruce Fir, Abies Excelsa. The term Burgundy is a 
misnomer, the resin never having been collected at or near Burgun- 
dy — Finland, and to a smaller extent Baden and Austria, being the 
countries whence it is derived. Its constituents closely resemble 
those of common resin. It is often adulterated and imitated by a 
mixture of resin with palm oil, water, etc., from which it may be 
readily distinguished by its duller yellow color, highly aromatic 
odor, greater solubility in alcohol, and almost complete solubility in 
twice its weight in glacial acetic acid (Hanbury). 16. Podophyllum- 
resin. In preparing the resin of podophyllum, or May-apple (Re- 
sina Podophylli, U. S. P.), an alcoholic extract of the rhizome and 
rootlets of Podophyllum peltatum (Podophyllum, U. S. P.) is poured 
into cold water ; the resin is then deposited. This resin is the chief 
active principle of podophyllum-root. According to Guareschi, po- 
dophyllin contains a glucoside resembling convolvulin. Podwis- 
sotzki Iras extracted from podophyllum a little crystalline coloring- 
matter, fat, a bitter crystalline acid, a bitter crystalline neutral 
principle, and an amorphous acid resin. 17. P'yrethrin is the name 
of the acrid resinous active principle of the root of Anacylus pyre- 
thrum or Pellitory-root {Pyrethrum, U. S. P.). According to Buok- 
heim, the action of alkalies breaks it up into piperidine and pyre- 
thric acid. The crystalline poisonous principle obtained by Bel- 
lesme from Pyrethrum cameum, the powder of which (and of P. 
roceum, and especially P. cineraria? folium, or Dalmatian Insect 
Powder) is the well-known " insecticide," has not yet been analyzed. 
18. The resins of Rhubarb have already been alluded to in connec- 
tion with Chrysophanic Acid. 19. Rottlerin, C n II 10 O 3 (mallotoosin, 
CjiIIkAjj Perkin), is the name given by Anderson to a crystal lino 
resin from Kamala {Kamala, U. S. P.), the minute glands that cover 
the capsules of Rottlera tinctura: to this and, apparently, allied 
resins, Kamala owes its activity as an anthelmintic. 

Oleo-resins. — 1. " Capsiein," a term suggestive of a definite 
chemical substance, is a name somewhat unhappily accorded to 
an indefinite substance, an oleo-resin, obtained by digesting the 
alcoholic extract of Capsicum-fruit {Capsicum, U. S. P.) in other 
and evaporating the clear ethereal fluid to dryness. Besides vola- 
tile oil and rosin, eapsieuin-fruits contain much fatty matter which 
Thresh states is chielly free palmitic acid. (See also Capsicine and 



422 ORGANIC CHEMISTRY. 

Capsaicin, in Index.) 2. Copaiva {Copaiba, U. S. P.) is a mixture 
of essential oil (C 15 1I. 24 ), copaivaol, C 20 H 32 (Strauss), -with 2 or more 
per cent, of brown soft resin, and 30 to 60 of a } T ellow dark crystal- 
line resin consisting mostly of copaivic acid (C 10 H 30 O 2 ), with oxy- 
copaicic acid, C 20 H 28 O 3 (Fuhling) and metacopairic acid, C^H^O^ 
(Strauss). Copaiva, containing about equal parts of this acid and 
of the oil, heated with a fourth of its weight of the official carbo- 
nate of magnesium, yields a transparent fluid, owing to the forma- 
tion of copaivate of magnesium and solution of this soap in the 
essential oil. "With an equal weight of the carbonate enough soap 
is produced to take up the whole of the essential oil and form a 
mass capable of being rolled into pills. A much smaller quantity 
of calcined magnesia, as might be expected, effects the same result ; 
but more time, often several days, is required before complete reac- 
tion is effected. The Messa copaiba?, U. S. P., is formed from 6 parts 
of magnesia and 94 of copaiva. Quicklime has a similar effect. 
Perhaps carbonate reacts more quickly because of its fine state of 
division and admixture of hydrate — in which case hydrates of cal- 
cium and magnesium may be expected to act better than the calcined 
preparations, and in much smaller quantity than carbonate of mag- 
nesium. Copaiva, unlike 3, Wood-oil, or Gurjun Balsam (Dipttro- 
carpi Balsamum, P. I.), a similar oleo-resin from the Dipterocarpns 
turbinatus (D. Lcevis, P. I.), does not become gelatinous when heated 
to 270° F. Copaiva is often slightly fluorescent; Gurjun balsam is 
highly fluorescent. The stated analogy of Gurjun balsam to copaiva 
is borne out by its chemical composition, for by distillation it yields 
about 40 per cent, of an essential oil identical in composition with 
oil of copaiva, the non-volatile portion being resinous. The adul- 
teration of copaiva with fixed oil is best detected by heating 20 or 
30 drops in a capsule until all essential oil has evaporated. Turpen- 
tine is betrayed by its odor during this evaporation. The residue, 
copaiva resin, is brittle if pure, and more or less sticky or soft if 
fixed oil is present. The limit of brittleness is stated, by Siebold, 
to be reached when 1 per cent, of oil has been added to the copaiva, 
that amount preventing the residue being reduced to a fine powder. 
" The essential oil distilled off from the oleo-resin. when rectified, 
should not begin to boil below 200° C. (392° F.). On adding 1 drop 
of copaiba to 19 drops of disulphide of carbon and shaking the 
mixture with 1 drop of a cold mixture of equal parts of sulphuric 
and nitric acids, it should not acquire a purplish-red or violet color 
(absence of Gurjun balsam)." — U. S. P. Resina Copaibce, U. S. P., 
is the residue left after distilling off the volatile oil from copaiba. 
4. Oleo-resin of cubebs (Oleo-Resina Cubebce, B. P.) is an ethereal 
extract of cubebs decanted from waxy matter (see Piperine and Oil 
of Cubebs). 5. Elemi {Elemi, B. P.) is an exudation from a tree grow- 
ing in the Philippine Islands. It consists of volatile oil (C 10 H 16 ), with 
80 or more per cent, of two resins, the one (C 20 H 32 O 2 ) soluble in cold 
alcohol, the other, Ami/rin (C 5 II 8 ) 5 H 2 0, almost insoluble, associated 
with Amyric acid (C 5 H 8 ) 7 + (Buri). There is an a and a (3 amyrin, 
each having the formula C 30 H 49 OH (Vesterberg). It also contains 
small quantities of two crystalline bodies soluble in water. Bryoidin 



GUM-RESINS. 423 

(C 5 H 8 ) 4 3H 2 0, and Breidin (Fliickiger). The Icacin of Stenhouse and 
Groves is either identical with amyrin or perhaps has the formula 
(C 5 H 8 ) 9 H 2 0. All these bodies are probably hydrous terpenes. 6. 
Wood-tar (Fix Liquida, U. S. P.) is a mixture of several fo inoid 
and oily bodies (amongst others Creasote ; see Index) obtained by 
destructive distillation from the wood of Finns sylvestris and other 
pines. When heated it yields a terebinthinate oil (Oleum Picis 
Liquidce, U. S. P.) and a residue of pitch. 7. Turpentines. These 
oleo-resins have been mentioned in connection with oil of turpentine, 
their volatile, and resin, their fixed, constituent. 8. Common Frank- 
incense (Thus Americanum, B. P.) is the concrete turpentine of Pinus 
tceda. 9. Canada Balsam (Terebinthina Canadensis, B. P.) is largely 
gathered in the province of Quebec, and is the turpentine or oleo- 
resin of the Balm-of-Gilead Fir (Abies balsamea). 10. Sumbul-root, 
from Ferula Sumbid (Sumbid, U. S. P.) contains 9 per cent of resin, 
to which probably it owes its stimulating properties. The resin con- 
sists of two parts — one soluble in ether and the other in alcohol, 
together with valerianic, sumbulic, and sumbuolic acids. By dry dis- 
tillation it yields a blue oil. 11. Oleo-resin of Lupulin (IT. S. P.) is 
an ethereal extract of the yellow glandular powder (Lupulinum, 
B. P.) attached to the small nuts at the base of the scales which 
form the aggregate fruit of the Hamulus Lupulus, or Hop (Humulus, 
U. S. P.). It contains essential oil of hop (valerol, C 6 H 10 O), oxidized 
oil or resin, bitter extract containing the hop-bitter, lupulinic acid 
(C 32 H 50 O 7 ), and tannic acid. It generally contains a good deal of 
earthy dust, but should not yield more than 15 per cent, of ash and 
not more than 30 or 40 per cent, of matter insoluble in ether. Oleo- 
resinos Aspidii, Capsici, Cubebce, Piperis, and Zingiberis are official 
in the United States Pharmacopoeia. 12. Fix Canadensis, U. S. P. 
(Canada Fitch or Hemlock Pitch), is the concrete juice of Abies 
Canadensis. 

Gum-resins. — 1. Ammoniacum (Ammoniacum, U. S. P.) is an exu- 
dation from the Dorema Ammoniacum. It contains nearly 20 per 
cent, of gum, a little volatile oil, and about 70 of resin (C 40 H 50 O 9 — 
Johnston). 2. Asafoetida (Asafoetida, U. S. P.), formerly spelled 
assafoetida, is a gum-resin obtained, by incision, from the living 
root of Narthex asa-foetida. It contains from 50 to 70 per cent, of 
a resin which is partly ferulaic acid (C 10 II 10 O 4 ), 25 to 30 per cent, of 
gum (about two-thirds arabin, one-third bassorin, p. 113), a little 
vanillin, and 3 to 5 per cent, of volatile oil, which is probably a sul- 
phur derivative of allyl, but owing to its overpowering odor it has 
not yet been examined. 3. EiipJwrbiuni, an old drug which is an 
emetic and purgative resin. It contains an amorphous active resin 
(^(J^OJi crystalline euphorbon (C 26 H 44 2 ), and mucilage (Fllicki- 
ger). 4. The ordinary or Siam Gamboge (Cambogia, U. S. P.) of 
European trade is obtained from the Garcinia morella ; the gamboge 
of India (Cambogia Indira vel Mysoriensis, P. I.) from G. pictoria. 
When of best quality it contains about 20 per cent, of a gum. and 
80 to 75 per cent, of a yellow resin termed gambogic acid 
(^20^23^4)- * r> - Galbanum (Galbanum, V. S. P.) contains from 20 to 
25 per cent, of gum, about 05 per cent, of resin (^ 10 U :)l O 7 ), and 3 or 



424 ORGANIC CHEMISTRY. 

4 per cent, of volatile oil. Moistened with alcohol, and then with 
hydrochloric acid, galbanum yields a purple color, due, probably, to 
the production and oxidation of resorcin. Galbanum heated for 
some time to 212° F. with hydrochloric acid, the liquid separated 
and shaken with ether or chloroform, and the latter evaporated, 
yields somewhat less than 1 per cent, of colorless acicular crystals 
of umbelliferone (C 9 H 6 3 ). " Umbelliferone is soluble in water : its 
solution exhibits, especially on addition of an alkali, a brilliant blue 
fluorescence which is destroyed by an acid. If a small fragment of 
galbanum is immersed in water, no fluorescence is observed, but it 
is immediately produced by a drop of ammonia. The same phe- 
nomenon takes place with asafcetida. and in a slight degree with 
ammoniacum-, it is probably due to traces of umbelliferone pre- 
existing in those drugs. Umbelliferone is also produced from many 
other aromatic umbelliferous plants, as Angelica, Levi sti cum, and 
Meum, when their respective resins are submitted to dry distillation ; 
also from the resin of Daphne mezereum. The fluorescence of umbel- 
liferone may be beautifully shown by dipping some bibulous paper 
into water which has stood for an hour or two on lumps of galba- 
num, and drying it. A strip of this paper placed in a test-tube of 
water with a drop of ammonia will give a superb blue solution, 
instantly 'losing its color on the addition of a drop of hydrochloric 
acid" (Fliickiger and Hanbury). 6. Myrrh (Myrrha, U. S. P.), an 
exudation from the stem of Bahamodendron nu/rrha, contains about 
half its weight of soluble arabinoid gum, 10 per cent, of insoluble 
gum (probably bassorin). 2J of volatile oil, and about 25 per cent, 
of resin (myrrhic acid). 7. OUbanum (P. I.), Thus masculvm or 
Arabian Frankincense (from various species of Boswellia), is about 
one-third gum and nearly two-thirds resin (C 40 H 30 O 6 ), with a little 
hydrocarbon (C ]0 H lfi ) and oxidized hydrocarbon volatile oils. It has 
always been an important ingredient of incense — myrrh, storax, 
benzoin, and such fragrant combustible resinous substances being 
other constituents. 8. Scammony (see Index). 

Gum-resins need only to be finely powdered and rubbed in a mor- 
tar with water to yield a medicinal emulsion, in which the fine par- 
ticles of resin are held in suspension by the aqueous solution of 
gum. 



QUESTIONS AND EXERCISES. 

695. What are the general chemical characters of volatile oils? 

696. How do volatile oils usually differ chemically from fixed 
oils? 

697. Describe the usual process by which volatile oils are obtained. 

698. How does natural turpentine differ from turpentine of trade? 

699. With what object is commercial turpentine rectified? 

700. What is the chemical nature of india-rubber and gutta- 
percha ? 

701. How is india-rubber vulcanized and converted into ebonite or 
vulcanite? 



BENZENE HYDROCARBONS. 42o 

702. Mention the difference in composition between the volatile 
oils of Anthemis nobilis and Matricaria chamomilla. 

703. Give the systematic name for oil of horseradish. 

704. State the general composition of the oils of lemon, lime, ber- 
gamot, citron, and cedra. 

705. Name the constituents of oil of cloves. 

706. In what respect does oil (or otto) of roses differ from volatile 
oils? 

707. To what class of substances do the constituents of oil of rue 
belong? 

708. How is camphor oil related to camphor? 

709. In what respects do Borneo or Sumatra camphor and cam- 
phor oil differ from the corresponding products of Japan and 
China? 

710. Hoav may borneol be artificially prepared? 

711. How do resins occur in nature? Distinguish between resins 
and camphors. Mention the points of difference of resins, oleo- 
resins, gum-resins, and balsams. 

712. Name the source of the chief constituents of common resin 
or rosin. 

713. Enumerate some official articles of which the active constitu- 
ents are resins. 

714. Give the distinguishing characters of Burgundy pitch. 

715. What is the average proportion of oil and of resin in the 
so-called balsam of copaiva? 

716. Explain the effect of carbonate of magnesium, magnesia, and 
lime on copaiva. 

717. Why do ammoniacum, asafoetida, gamboge, galbanum, myrrh, 
and similar substances give an emulsion by mere trituration with 
water ? 



THE BENZENE SERIES OF HYDROCARBONS. 

The Benzene or Aromatic Series, C n H 2n - 6 . — This series, to which 
during the last few years most attention has been paid, yields, like 
other families of hydrocarbons, alcohols, haloid derivatives, alde- 
hydes, acids, etc., obtained, however, as a rule, by special rather than 
general methods. Just as the consecutive members of the paraffin 
series of hydrocarbons may be regarded as derived by the displace- 
ment of a hydrogen atom of the previous member by the methyl 
(CII 3 ) group, or of a hydrogen atom in methane by a paraffin radi- 
cal, so the consecutive members of the benzene series may for con- 
venience of study be viewed as obtained by the displacement of a 
hydrogen atom in benzene by a paraffin radical ; as in the following 
samples : — 

Benzene or Phenoene, C 6 H 6 . 

Toluene, Benzoene, or Methylphenoene, C 7 H 8 or C 6 H 5 CH 8 . 
Xylene or Ethylphenoene, C 8 H 10 or (\.I1,.(U1 V 
Mesitylene or Trimethylphenoene, C^M,., or C 6 IL(CH S ) 3 . 
Cymene or Methylpropylphenoene, C 10 H W or C 6 H 4 .CH 3 C 3 H r 
36 * 



426 ORGANIC CHEMISTRY. 

It is perhaps desirable, as suggested by Odling, to designate the first 
member of this series by the name phenoene, rather than benzene, 
as its hydrate is termed phenol, and its derivatives phenyls — e. g. 
phenylamine. Toluene (first obtained from balsam of tolu, hence the 
name) then becomes benzbene : from it benzoic acid is derived. 

The members of the benzene series are unsaturated hydrocarbons. 
A molecule of benzene itself readily absorbs two, four, or six atoms 
of chlorine, these, being added on to the benzene, forming what are 
termed additive compounds, as distinguished from the true substitu- 
tional compounds, in which the hydrogen atoms in benzene are actu- 
ally substituted by chlorine, bromine, etc. 

Bodies having an aromatic odor are somewhat characteristic of the 
benzene series ; hence the latter is often termed the aromatic series 
of organic compounds. 

Benzene or Benzol. 

Benzene or Phenoene, C 6 H 6 (commercially known as Benzol)* — 
Commercially, it is obtained from the portion of coal-tar boiling 
below 100° C. It is partially purified by shaking successively with 
sulphuric acid, water, and caustic soda, and then redistilling, the 
product still containing large quantities of toluene and other impuri- 
ties. If pure benzol is required, the liquid must be subjected to a 
freezing mixture, when the benzol crystallizes out, leaving some 
impurities in solution : the crystals are then drained. Bromine is 
then added to the liquid resulting from the melting of the crystals 
until a permanent coloration results. The liquid is again washed 
with caustic soda, and distilled. Benzene boils at 81° C. It may 
be artificially produced by heating benzoic acid with lime or by 
passing acetylene through red-hot tubes. It is a colorless, limpid, 
refractive liquid, having a specific gravity of 0.9. It is a powerful 
solvent of grease, and under the name of benzine collas was intro- 
duced by M. Collas in 1848 for cleansing purposes. 

Benzene when acted on by chlorine and bromine in the presence 
of a little iodine, forms all derivatives from monochloro- and mono- 
bromobenzene (C 6 H 5 C1 and C 6 H 5 Br) to hexachloro- and hexabromo- 
benzene (C 6 C1 6 and C 6 Br 6 ). It also forms iodine and fluorine deriva- 
tives, nitro-derivatives, etc. 

Nitrobenzene (nitrobenzol, artificial oil of bitter almonds, or 
essence of mirbane), C 6 H 5 N0 2 , is obtained by mixing fuming 
nitric acid or a mixture of nitric and sulphuric acids with ben- 

*Care must be taken to distinguish between benzene, C 6 ET 6 , and ben- 
zin, petroleum ether, benzolin, etc. (Petroleum Spirit, B. P.), which are 
mixtures of paraffin hydrocarbons of lower boiling-points. Benzin 
(U. S. P.), C 5 H ]2 : C 6 H U , and other hydrocarbons of the paraffin series 
having the boiling-point of 122-140° F., requires six times its bulk of 
alcohol for solution, whereas benzene, C 6 H 6 , dissolves in less than its 
own bulk. Specific gravity of benzene, about 0.850 ; of benzin, about 
0.700. 






BENZENE HYDROCARBONS. 427 

zene, the vessel being kept cool by immersion in water. It is a 
yellow liquid, heavier than water, having a strong odor of oil 
of bitter almonds, though of very different nature. ( Vide 
"Oil of Bitter Almonds" in Index.) When acted on by 
nascent hydrogen it yields aniline. 

Aniline, or PJienylamine ,or Amidobenzene, C 6 H 5 NH 2 * — Mix 
13 parts of iron filings, 7 or 8 of acetic acid of sp. gr. 1.05, 
and 13 of nitrobenzene, in a large flask (with an .upright con- 
denser) placed in a water-bath, and set the whole aside for some 
time. After the mixture has digested for several hours, the 
supernatant liquid is poured off from the deposit of iron filings 
and distilled in a current of steam. By this method the nitro- 
benzene yields, first, aniline, distilled over as a yellow oil, and 
afterward a red oil, which is a mixture of azobenzene, hydrazo- 
benzene. and azoxybenzene. 

Aniline, when acted on by arsenic acid or chlorinated lime, pro- 
duces roseaniline, C 20 H 19 N 3 , whose salts and derivatives form most 
of the well-known aniline colors. Dinitrobenzene is also known. 

Constitution of Amines. — Amines are usually viewed as deriva- 
tives of ammonia, one, two, or three atoms of hydrogen being 
replaced by one, two, or three monatomic organic radicals, or equiv- 
alents of radicals of higher quantivalence. The products were 
formerly known as amidogen (NH 2 ) bases, imidogen (NH) bases, 
and nitrile (N) bases, but are now termed primary, secondary, and 
tertiary amines. They are of special interest because alkaloids are 
included in this class. Thus : — 

Nf H HAH 

\H \H 

Ammouia. Phenylaniine. 

(For other examples, vide "Alkaloids" in Index.) 

Toluene, Benzoene, Methylphenoene, or Methylbenzene, known also 
as Toluol, C 6 H 5 CH 3 , forms the principal portion of coal tar, boil- 
ing between 100-120° C. ; it may be synthetically made by acting on 
monochlorobenzene and iodomethane by sodium. 

C 6 H 5 C1 + CH 3 I + Na 2 = C 6 H 5 CH 3 + Nal + NaC. 
It is also obtained by the dry distillation of tolu balsam. It is an 
inflammable, refractive liquid, boiling at 111° C. It may be directly 
oxidized to benzoic acid. 

2C 6 H 5 CH 3 + 30 2 == 2C 6 II 5 COOH + 211,0. 
Having both a phenyl (C 6 II 5 ) and a methyl (0II 3 ) group in its mole- 
cule, it forms two sets of isomeric derivatives: one (a) in which, 

* Aniline maybe obtained from indigo, hence its name, anil being 
Portuguese for indigo. 



428 ORGANIC CHEMISTRY. 

by acting on toluene in the cold, the atoms of hydrogen are dis- 
placed in the phenyl group, and the other (6) by acting on boiling 
toluene, in which the atoms of hydrogen in the methyl group are 
displaced.* 

[ Tolyl chloride, or methylmonochlorobenzene, C 6 H 4 C1.CH 3 . 
a < Tolyl dichloride, or methyldichlorobenzene, C 6 H 3 C1 2 CH 3 . 
(Tolyl trichloride, or methykrichlorobenzene, C 6 H 2 C1 3 CH 3 . 

f Monochloromethylbenzene, or benzyl chloride, C 6 H 5 CH 2 C1. 

b < Dichloromethylbenzene, or benzyl dichloride, C 6 H 5 CHC1 2 . 

(Trichloromethylbenzene, or benzyl trichloride, C 6 H 5 CC1 3 . 

Dichloromethylbenzene, when acted on by glacial acetic acid and 
zinc chloride and water, produces benzoic aldehyde, C 6 H 5 COH 
(Jacobson). By acting on trichloromethylbenzene by water in 
sealed tubes benzoic acid results. 

C 6 H 5 CC1 3 + H 2 = C 6 H 5 COOH - 3HC1. 

Cymene, C 10 H U . — Propylmethylhenzene, C 6 H 4 (CH 3 )(C 3 H 7 ) occurs 
in seyeral yolatile oils, and is readily obtained by the removal of 
hydrogen from the terpenes (C 10 H 16 ) of those oils. Many of the 
members of the benzene series have an aromatic odor, hence the 
synonym aromatic series. 

Constitution of the Benzene Series. 

The fact that benzene forms three additive derivatives with chlo- 
rine, C 6 H 6 C1 2 . C 6 H 6 C1 4 . and C 6 H 6 C1 6 . 1 molecule uniting with not 
more than 6 atoms of chlorine, and that it affords no isomeric mono- 
substitution-derivatives, led Kekule to represent benzene by the fol- 
lowing figure (a), in which each atom of carbon is assumed to be 
linked to an adjacent atom of carbon by three-fourths of its affinity, 
the remaining fourth of its attraction being exerted toward the equiv- 
alent attraction of another atom, thus (Fig. a) : — 

Fig. a. Fig. b. Fig. c. 

HC1 
H 

H c / V 1 

HC CH 6/ ^2 C1Y TCI 



HC CH b\ )3 II' I II 

Cl\ / CI 



c 

H C 



HC1 

Hexachlorobenzene. 



*" Benzyl" is the name given to the derivatives of benzoene when 
substitution takes place in the methane nucleus, " tolyl," when in the 
phenoene nucleus, 



HYDROCARBONS — ALOINS. 429 

In a mono-substitution-derivative such as chlorobenzene, C 6 H 5 C1, 
no matter where the atom of chlorine be placed, it bears the same 
relation to the other atoms of hydrogen ; but in dichlorobenzene, 
C 6 H 4 C1 2 , the atoms of chlorine may (representing, for the moment, 
benzene by an hexagonal figure (b), and assuming that the carbon 
atoms are at the angles) be either placed at 1 and 2, 1 and 3, or 1 
and 4, the chlorine atoms being either near to each other, separated 
by one carbon atom or by two carbon atoms ; and in trichloroben- 
zene, C 6 H 3 C1 3 , the atoms of chlorine may be placed at 1, 2, and 3 ; 
1, 2, and 4 ; or 1, 3, and 5 ; 1,2, and 4 being the same as 1, 3, and 
4; 1, 2, 3 the same as 1, 6, and 5, etc., that is to say, the chlorine 
atoms must all three be near to each other, or two near to each other, 
and one be separated, or all three be separated as far from each 
other as possible in the molecule. Hence, theoretically, there can 
only be three isomeric di- and trichlorobenzenes ; which has been 
verified by experiment. (For other illustrations see page 457.) In 
the additive compounds a second quarter of the affinity of the car- 
bon atoms for each other is freed, so to say, for exertion toward the 
added chlorine atoms (Fig. c). 

OTHER SERIES OF HYDROCARBONS. 

The Naphthalene Series, C n II 2n _ 12 . 
Naphthalene, C 10 H 8 , is the only important member of this series. 
It is a white crystalline body, existing in the higher fractions of coal 
tar. By oxidation it yields phthalic acid, the anhydride of which, 
when fused with phenol, forms phenol-phthalein, used as an indica- 
tor in alkalimetry. Crude naphthalene is employed for increasing 
the luminosity of ordinary coal gas. 

The Anthracene Series, C n II 2n _ 18 . 
Anthracene, C, 4 H 10 , is the only noteAvorthy member of this series, 
its importance being due to the fact that artificial madder, or aliza- 
rin, is formed from it by the following reactions : Anthracene is 
first oxidized to anthraquinone by the influence of the nascent oxy- 
gen of nitric acid. 

CuH 10 + 30 = C M H 8 2 -f 0H 2 . 

By acting on anthraquinone by bromine, it is easily converted into 
a dibromo-derivative, which yields alizarate of potassium when fused 
with caustic potash, 

C u TI 6 Br 2 2 + 4KII0 = C M IT fi (OK) a O a + 2KBr + 211,0. 

Chrysophanic acid (CII 3 C 14 TT s (OII). 2 2 ) and the aloins are related 
to anthraquinone; chrysophanic acid being a dihydroxy-derivative 
of methylanthraquinone, and the aloins (C ie H 18 O t ) yielding on oxi- 
dation aloxanthin or tetrahydroxy-methylanthraquinone. 



Aloins. 
Aloins.— The aloes (Aloe, U. S. P., and Aloe Socotrina, B. P.) is 

an evaporated juice, doubtless much altered by the temperature to 



430 ORGANIC CHEMISTRY. 

which it is subjected. Aloe Purificata, U. S. P., is the evaporated 
alcoholic extract. It contains a yellow crystalline substance. Aloin 
(B. P.), slightly varying chemically, but not medicinally, as derived 
from the respective species of aloes. Aloin is slightly soluble in 
cold water or spirit, but readily soluble in the hot fluids. Dissolved 
in alkalies, it rapidly absorbs oxygen, but it is not readily altered in 
neutral or acidified solutions. 

Aloin may readily be obtained from either kind of aloes by warm- 
ing with three or four times its weight of amylic alcohol ; pouring 
off the solution ; allowing it to stand for a few hours to crystallize ; 
and washing the deposited aloin with ether or bisulphide of carbon 
to remove resinoid matters. 

Barbaloin. — This substance, first obtained by T. and H. Smith, 
occurs in minute crystals in Barbadoes aloes. It yields, by the 
action of bromine and chlorine, substitution compounds. Nitric 
acid dropped upon it produces a red color, which soon fades. 
Boiled for some time with strong nitric acid, barbaloin gives, 
together with oxalic and picric acids, a yellow substance, chiys- 
ammic acid, which furnishes beautiful red salts (Tilden). Anthra- 
cene (C U H 10 ) has been obtained by deoxidation of barbaloin. 

Nataloin. — This body was discovered by Fliickiger in Natal aloes. 
It crystallizes readily in rectangular plates, either from spirit or 
from water. No bromine or chlorine substitution-derivatives have 
yet been formed, but an acetyl compound has been analyzed (Til- 
den). Nataloin moistened with nitric acid gives a red coloration 
which does not fade. When boiled with nitric acid it yields no 
chrysammie acid, but only oxalic and picric acids. 

Socaloin or Zanaloin. — Histed and Fliickiger have shown that 
Socotrine or Zanzibar aloes yields an aloin distinct from those just 
described. It forms tufted acicular prisms. Nitric acid scarcely 
alters the color of socaloin. Neither socaloin nor barbaloin 
affords any color when vapor from a glass rod moistened with 
nitric acid is brought near to a drop of oil of vitriol containing 
a minute fragment of the aloin, while nataloin gives rise to a 
blue coloration. 

Analysis. — To aloin or powdered aloes on a white plate add 
strong nitric acid. No color = socaloin. Crimson color = nataloin 
or barbaloin. To another portion add strong sulphuric acid and 
vapor of nitric acid. A blue color — nataloin. No blue color = 
barbaloin. 

(For other methods of distinguishing the aloins. and other allied 
bodies, see a paper on Aloins by Cripps and Dymond, Pharmaceu- 
tical Journal. February 7. 1885.) 

E. von Sommaruga and Egger (" Pharmaebgraphia ") arrived at 
the conclusion that the aloins form an homologous series, and that 
they have the composition indicated in the following formula) : 
Socaloin, C 15 II 1C 7 : Nataloin, C 16 II 18 7 ; Barbaloin, C ]7 H 20 O 7 . Til- 
den's subsequent experiments indicate, however, that barbaloin 
(C ]r H 18 7 ) and socaloin (C 16 H 18 7 ) are isomeric in the anhydrous 
state, but that socaloin and its derivatives in the hydrous condition 
contain more water of crystallization than barbaloin. Nataloin 



I DERIVATIVES. 



Naphthalene 


ChHio Anthracene 


v. f Naphthalene chloride 
{ Chlorouaphthalene 


CuH 9 Cl /Anthracene chloride 
( Chloroanthracene 


\02 Nitronaphthalene 




■ZH'2 Naphthalaraine 




w f Naphthvlic alcohol or 
JrL J Napththol 


C14H9.OH {Anthracene alcohol 
( Anthrol 


r\-rr\ { Naphthaqninol or Di- 
2 ( hydroxynaphthalene 


CuH 8 ;OH) 2 (Anthraqninol or Di- 

' ( hydroxyanthracene 


QTT V f Trihydroxy- 

3 ( naphthalene 












^ f Naphthonitrile 

1 Naphthylic cyanide 

























ociation of two OH groups with one atom of Carbon is unusual. (See page 309.) 



ALCOHOLS. 431 

(C 16 H 18 7 ) seems to be isomeric with the others, but is less soluble, 
and does not yield either chrysaminic acid or chloro- or bromo-deriva- 
tives (C 16 H 15 C1 3 7 ; C 16 H 15 Br 3 7 ). The acetyl-derivatives appear to 
have the formula, C 16 H 15 (C 2 H 3 0) 3 7 . 



QUESTIONS AND EXERCISES. 

718. What is the formula of benzene? How is it artificially and 
commercially prepared? 

719. Draw out an equation explanatory of the production of 
aniline. 

720. What is the relation between toluene and benzoic acid? 

721. Give the formulae of naphthalene and anthracene. 

722. Explain by equations the production of alizarin or artificial 
madder. 

723. Give tests for distinguishing the aloins. 



The student is referred to the accompanying table for a general 
view of the relations of four series of hydrocarbons (the paraffin, 
benzene, naphthalene, and anthracene series) to each other. Three 
members of the paraffin series are shown, two of the benzene series, 
and one each of the naphthalene and anthracene series. Beneath 
each hydrocarbon is given its chief derivatives. A glance along 
the table shows the relation of these derivatives to each other. 



ALCOHOLS. 

Alcohols are those bodies in which one or more hydrogen atoms 
of the hydrocarbons are displaced by one or more hydroxy 1 (Oil) 
groups, forming (a) monhydroxyl derivatives, (6) dihydroxyl deriva- 
tives, etc. ; they are, in fact, hydrates of unsaturated or radical 
hydrocarbons, just as caustic potash and slaked lime are hydrates 
of potassium and calcium ; thus : — 

C 2 H 5 OH KTIO or KOII 

Ethyl hydrate. Potassium hydrate. 

C 2 H 4 (OII) 2 Ca(OTl)., 

Ethylene or glycol hydrate. Calcium hydrate. 

C 3 H 5 (OH) 3 Bi(OIl), 

Glyceric hydrate or glycerin. Bismuth hydrate. 

a. Monhydroxyl Derivatives of Paraffins. 

tThe Ethylic Series of Alcohols, C n H 2n+1 OH.— The alcohols, or car- 
binols (Kolbe), are primary, secondary, or tertiary according as one, 
two, or three atoms of hydrogen in the first member of the series 
(methylic alcohol or carbinol itself, CH 3 OH) are displaced by one, 
two, or three atoms of any radical having the general formula 
C ft H 2n+1 . Thus:— 



To face page 431. 




PTIOAL TABLE SHOWING T 


IE RELATIONS 




,:,:s THE PRINCIPAL MEJIBE 


RSOFT 


IE PARAFFIN, I 




NAPHTHALENE, ANn 


.VNTHRACENF. SERIES OF I 


rDROOARBOm, A 




THEIR , 


KII1V.V 


IVES. 








HvDBOCABBON 


CHi Methane. 


,,,.„,„,„, 


"!" : ! "','„:" m 


ithyl- 


CiH, or CjHs.CHa 


'T!h' 


e or Ethyl- 


CsHs 


r > KeT/c". e c 0r 


C,HsorC 6 H,CH, 


! B, t'h\ z iph,",!;.'-,,'e" 1 


enc or Me- 




N., 


h.ha.ene 


0,11, 






"=».,,„ ( 


CH.CL { ^ron^lat " C°&C1 or C&CIMl | E g»*£ « 


(II el ..i ■(•,.II.-,.CII,.C1 j 1 ' ; j; ] l ;; | ' 1 ' | | i ' i '"''' 1, ' "' h '""" 


0AC1 


[ P Ch7„rotenzeue 0r 


GH.Cl or g«g^ H c 3 , 


{ch.oroto.nencs^ 


,';'chh!;'d, 


c,„h ; c, 


mil 


:':■'■,:, .';.'■■' 


d0 Ci.IMl 


: n',!,!;:::;;;;;;; 


'";!:;: 


CH.NC, { lk N t ^ n : 1 Jthauc '' M&»°" or CH s CLT,NO, { Et ^' oetha ° ° 


c.lhNi !.■...•( .11 1 II. NOi 




u.rite or Nitro- 


C.H.NO, 


{ P Nltroh'n^e " r 


'^^'■'''Ijl'ri'i'v'.' 


{Nitrotolnenes £, 


%"«*«* 


C,.,„:N„ 


Nil 












CHsNII, Mothylam.no 


C, M ,. t CH«H, 


( -..II.-MI.. ..rC.|I.CH-...SH J Propylamine 


c.ji.mi, • '''V.'.'iil;', 1 '. 1 '" 1 ' " r 


•^^"^r^LuU!!: 


IKS: 






N,|. 


thalamino 








M °— — 


c ^o°^} M S!cr ' 


CaHsOH orCHsCHiOH 




rMe- 


C^OHo {(CH,hCH.OH 




:'S; : tll 


C'oiioOU j 1> '^ 1 ' 1 '; v ,' I „ 1 " Uo '"' 1 '"' 


CH,.OHorg i:c OH o CH 3 


{SStfaass 


»t.car „, 




(Nap 


,:!i^i ;i ""'" 


'"'. C14H0.OH 


Mr 


„„„„, 






D.nvon.c Alcohol 




CiH.(OII)«m ■CII.-iHI .cll.-nll 


1 Etliyli-n.' cly. 

1 Glycol 


lor 


('iLWOIlk or CjHiOH.CHiOU 


Propyler 


glycol 


f„llfiili ,. ' I;'- .'.'.■','„'' "' 


CiHilOH), or CoHi.OH.CHjOII 


pa^lalololSa, 


f ono> or Hy 


C.ll (HI 


TrH 


!^L_ 


',". C,,1I-.01I], 


! X''.ii''">" 


,„;;,:::■ 


TB.HYHB.C ALCOHOL 






1 .11. nil ,„■ ( ,11.(111 .cll.dll Glycerol or Glycerin 


(WOH), j P ^c^ia rPyt °- 










*«»™ 


C, [i co°n !^^>»* 


C^OorCH,CO.H Acetic aldehyde 


CIIoO or cJHs.CO.H Propionic aldehyde 




dfcOorGH.CO.H 


Benzoic aldehyde 














K"™" 






CH 8 Oorcjl,CO.CH, 




or Dimethyl 








NIXB.LE 


'""^ : v, ,',:;':", ! ;;:;,i,;::' M " 


CH.CN or CHsCH.CN {^"''•vl.ni'.ic 


( i,,x.„ 1 mu-h j c N { B, c ?a™;,i'' i ;:,,;:::,,v'' ,1 ' y ' 


CsHsCN 


i B phcSyTcyanIde 


C7H1CN or C0H5CH2CN 


Benzyl cyanide 




CoH'CN l^li^^^nide 


"""^X*! l "■ C0 -° H * F ° rmiC " Cia ^ H<0 ' ° r CHlC0 -° H 1 A tl^formtc °cid MC - ^0, or C,H,CO.OH { '2?* "' ^ 




CHsOiOlCsHi.CO.OH 


{Benzoic acid or 


henyl-formic 




M0!,MAB ' C (WM,k) 


''. ".'.'■' .".',!'; ;":;;",,. ...:;.,r- 


o,ao,orcaoH.co.oH l (il ^;i,:;:,;;! ;;:,:;> - 


.,ii.... i .,.:,H,(..i..<i(H, ! '-;:;,•';;;;! ;;:;,,">■■"■"■- 




C;II„(), or C.ill.CHI. Cll.dll | ^''j.'^ 1 ''' ; "' i ' 1 '"' " y ' ■> ''■ ! '""' 




M0NO BA 8,O (Tiniv(]i . 0) 










C,ll,.(>, ... C..II...(III1...C(I.(I1I 1 <; ''„7„'„',',m," :iH,l 1> ' 1 '" X ' V " 




C:ll„(l, ..1 C..1I..III ...CII.OII 


Dihydrosyheuzoica 


cid 




DIBASIC S.CID 




<•:". Hz. II. 


Oxalic acid 




( II (11(111 .. 


Mal..,,i, 


,,-idt 


















Etheb 


.■(■II. Ml M.lll.vl ,-tlHT 


c II .() Ethyl ethev 


I ,1. Propyl ether 


(o,n 5 ho 


Phenyl ether 

















432 ORGANIC CHEMISTRY. 

-"- C„II 2H+1 ~C M H 2n+2 ^C. ft H 2n+1 

H— C— OH H— C— OH K — C— OH K— C— OH 

I I S | Q S | 

H H H C n H 2n+1 

Carbinol. Primary carbinol. Secondary Tertiary 

carbinol. carbinol. 

The primary oxidize their CH 2 OH group to aldehydes (COH) and 
acids (COOH), the secondary oxidize their CHOH group to form 
a ketone (a body having carbonyl, CO", as a group, as acetone 
CII3-CO-CH3), and by further oxidation break up, forming bodies 
with less carbon units than the original alcohol ; while the tertiary 
yield a ketone and an acid. The primary alcohols are of chief 
practical interest. The tertiary alcohols are said to be depressants 
instead of stimulants. (For examples of primary, secondary, and 
tertiary alcohols, see page 450.) 

General Method of Preparing Primary Alcohols. — By acting on 
the monochloro-derivative of a paraffin by acetate of potassium or 
silver an ethereal salt (acetate) is produced, which when saponified 
with caustic potash yields the alcohol. For instance, 

C 2 H,C1 + AgC 2 H 3 2 = C 2 H 5 C 2 H 3 2 + AgCl 

Ethylic "Silver Ethylic Silver 

chloride. acetate. acetate. chloride. 



C 2 H 5 C 2 H 3 2 


+ 


KHO = 


= C 2 H-,OH 


+ 


KC 2 H 3 2 


Ethylic 




Potassium 


Ethylic 




Acetate of 


acetate. 




hydrate. 


alcohol. 




potassium. 



If the chloro-derivative were directly acted upon by the lrydrate 
of potassium, hydrocarbons of the olefine and acetylene series Avould 
result. 

The chief alcohols are, however, otherwise obtained. 

Methylic Alcohol. 

Methyl Alcohol or Carbinol, CH 3 OH or HCH 2 OH (Pyroxylic 
Spirit or Wood Naphtha), is a product of the destructive distilla- 
tion of wood, and is now obtained in large quantities as a by-prod- 
uct in the manufacture of beet-sugar in France. By oxidation it 
yields formic acid (see page 405). 

Methylated Spirit. — Spirit of wine containing 10 per cent, of 
wood-spirit constitutes ordinary methylated spirit, a spirit issued duty 
free for the use of manufacturers, the methylic alcohol, etc. not inter- 
fering with technical applications. From its nauseous taste and 
odor, however, it cannot take the place of gin, brandy, or other 
spirit ; hence, while industry is benefited, intemperance is discour- 
aged and the revenue not injured. 

Detection of Methylic Alcohol in Presence of Ethylic Alcohol. — 
Three or four methods have been proposed for the detection of 
methylated spirits in various liquids ; that open to least objection 
is by J. T. Miller. For the application of the test to tinctures 



METHYLIC ALCOHOL. 433 

and similar spirituous mixtures, some of the spirit is first sep- 
arated by distilling off a drachm or so from about half an ounce 
of the liquid placed in a small flask or test-tube having a long 
bent tube attached. Into a similar apparatus put 30 grains of 
powdered red chromate of potassium, half an ounce of water, 
25 minims of strong sulphuric acid, and 30 or 40 minims of 
the spirit to be tested. Set the mixture aside for a quarter of 
an hour, and then distil nearly half a fluidounce. Place the 
distillate in a small dish, add a vei^ slight excess of carbonate 
of sodium, boil down to about a quarter of an ounce, add 
enough acetic acid to impart a distinct but feeble acid reaction, 
pour the liquid into a test-tube, add a grain of nitrate of silver 
dissolved in about 30 drops of water, and heat gently for a 
couple of minutes. If the liquid then nierely darkens a little, 
but continues quite translucent, the spirit is free from methylic 
alcohol ; but if a copious precipitate of dark-brown or black 
metallic silver separates, and the tube, after being rinsed out 
and filled with clean water, has a distinct film of silver, which 
appears brown by transmitted light (best seen by holding it 
against white paper), the spirit is methylated. 

Explanation. — This test depends for its action on the reducing 
powers of formic acid. In the above operation the ethylic alcohol 
becomes oxidized to acetic acid (the natural acid of the ethyl series), 
which does not reduce silver salts, a minute quantity only of formic 
acid being produced, while the methylic alcohol yields formic acid 
(the natural acid of the methyl series) in a comparatively large 
quantity. Aldehyde, which is also a reducing agent, is simultane- 
ously produced, but removed in the subsequent ebullition with car- 
bonate of sodium. 

Methylated Sweet Spirit of Nitre. — The preparation of spirit of 
nitrous ether from methylated spirit is illegal in Great Britain, 
and, probably, is very rarely practised. For the detection of 
methylic alcohol in this liquid, Mr. Miller suggests the follow- 
ing modification of the above process : 

Shake about an ounce of the sample with 20 or 30 grains 
of anhydrous carbonate of potassium, and, if needful, add fresh 
portions of the salt until it ceases to be dissolved, then pour 
off the supernatant spirit. This serves to neutralize acid and 
to remove water, of which an abnormal quantity may be pres- 
ent. Introduce half a fluidounce of the spirit into a small flask ; 
add 150 grains of anhydrous chloride of calcium in powder. 
and stir well together; then, having connected the flask with a 
condenser, place it in a bath of boiling water, and distil a fluid- 
drachni and a half, or continue the distillation until scarcely 



434 ORGANIC CHEMISTRY. 

anything more comes over. The operation is rather slow, but 
needs little attention and should be done thoroughly. The dis- 
tillate contains nearly the whole of the nitrous ether and other 
interfering substances, while in the retort there remains a non- 
volatile compound of chloride of calcium and methylic alcohol 
if the latter be present. Now add to the contents of the flask 
a fluiddrachm of water, which decomposes the compound just 
referred to, and draw over the half-drachm of spirit required for 
testing. Add it to the usual oxidizing solution composed of 30 
grains of red chromate of potassium, 25 minims of strong sul- 
phuric acid, and half an ounce of water ; let the mixture stand 
a quarter of an hour, then distil half a fluidounce. Treat the 
distillate with a slight excess of carbonate of sodium, boil rap- 
idly down to two fluiddrachms, and drop in, cautiously, enough 
acetic acid to impart a faint acid reaction ; pour the liquor into 
a test-tube about three-quarters of an inch in diameter ; add 
two drops of diluted acetic acid, U. S. P., and one grain of nitrate 
of silver in half a drachm of pure water ; apply heat, and 
boil gently for two minutes. If the spirit is free from 
methylic alcohol the solution darkens and often assumes 
transiently a purplish tinge, but continues quite translucent, 
and the test-tube, after being rinsed out and filled with water, 
appears clean or nearly so. But if the spirit contains only 
1 per cent, of methylic alcohol, the liquid turns first brown, 
then almost black and opaque, and a film of silver, which is 
brown by transmitted light, is deposited on the tube. When 
the sample is methylated to the extent of 3 or 4 per cent., 
the film is sufficiently thick to form a brilliant mirror. To 
ensure accuracy, the experiment should be performed by day- 
light. 

Ethylic Alcohol. 

Ethyl Alcohol, or Methyl Carbinol, commonly called simply Alco- 
hol (C 2 H 5 OH or CH 3 CH 2 OH). — It is a colorless liquid, having a 
boiling-point of 173.6° F. and sp. gr. 0.7935. Ethyl alcohol may be 
obtained by passing ethylene into strong sulphuric acid. The prod- 
uct, ethylhydrogen sulphate, when distilled with water yields 
alcohol : — 

C 2 H 4 + H 2 S0 4 = C 2 H 5 HS0 4 
C 2 H 5 HS0 4 + H 2 = C 2 H 5 HO + H 2 S0 4 . 

On the large scale alcohol is always formed by fermentation. 

Formation of Alcohol — Ferment two or three grains of 
sugar by dissolving it in a test-tube full of water, adding a 
little yeast (Cerevisise, Fermentwn, B. P.), or a piece of the 
so-called German or dried yeast, and setting the whole aside 



ETHYLIC ALCOHOL. 435 

for several hours in a warm place at a temperature of 70° 
or 75° F. ; carbonic acid gas is evolved, and, if the tube be 
inverted in a small dish containing water, may be collected in 
the upper part of the tube and subsequently tested : the solu- 
tion contains alcohol. If the experiment be made on larger 
quantities (four ounces of sugar, one of yeast, and a pint of 
water), the fermented liquid should be distilled, one-half being 
collected, shaken with a little lime, soda, or potash to neutralize 
any acetic acid and decompose ethereal salts, and again dis- 
tilled till one-half has passed over ; the product is dilute spirit 
of wine. It may be still further concentrated or rectified by 
repeating this process of fractional distillation. 

Fermentation. — The act of fermentation is commonly the result of, 
or rather accompaniment of, some vital action. Alcoholic fermenta- 
tion would appear to be always attended by or to attend develop- 
ment of life and free multiplication of cellular structure. It follows 
the development of the fungus already referred to as constituting 
the chief active part of yeast, the Saccharomyces cerevisice. In the 
presence of this fungus, with small quantities of phosphates and 
albumenoid matter, glucose is converted into alcohol and carbonic 
acid gas, together with small proportions of glycerin, succinic acid, 
and other substances. Yeast also contains a soluble ferment analo- 
gous to diastase, which is capable of converting sucrose into glucose. 
Therefore if yeast be used, sucrose or cane-sugar may be converted 
into carbonic acid gas and alcohol, the soluble ferment first convert- 
ing the sucrose into glucose. 

6 H 12 O 6 = 2C 2 H 5 IIO + 2CO, 

Grape-sugar. Alcohol. Carbonic acid gas. 

Not more than 20 per.cent. by weight of alcohol can be obtained 
in a fermenting fluid, for more than this proportion prevents fermen- 
tation. 

Other kinds of fermentation, arising from the action of special 
ferments which have not received in all cases distinctive names, are 
the following: Viscous or Mannitic fermentation, which occurs when 
beer or saccharine juices, such as that of beet-root, become "ropy." 
Gum, mannite, and carbonic acid gas arc produced. (For Lactic and 
Butyric fermentations, see "Lactic Acid.") Putrefactive fermenta- 
tion occurs when a liquid containing albumenoid matter is exposed 
to the air. Infusoria appear in the liquid, using up the dissolved 
oxygen, and the ferments of the genus Vibrio are developed. These 
are protected from oxygen, which is fatal to them, by a thin surface- 
layer crowded with bacteria — small, rod-like organisms having pow- 
ers of locomotion. The vibrionic action or putrefaction proceeds 
with evolution of sulphuretted hydrogen, together with other gases 
having unpleasant odors and of complex chemical constitution, 
(For Acetic j'ernientaf ion, see "Acetic Acid ;" for Annnoniacal fier- 
mvntalion, see " Urine.") 

Fermentation by Certain Soluble Albumenoids. — (For the eonver- 



436 ORGANIC CHEMISTRY. 

sion of starch into sugar by diastase, see " Starch ;" of amygdalin 
into benzoic aldehyde, hydrocyanic acid, and glucose by emulsin, 
see "Amygdalin-," of salicin into saligenin and glucose, see " Sali- 
cin ;" of myronate of potassium into sulphocyanide of allyl, etc., 
by myrosin, see "Mustard ;" of cane-sugar into grape-sugar by the 
soluble ferment in yeast, see the foregoing paragraphs.) 

Alcoholic Fermentation. — The chief reaction results, as already 
stated, in the formation of alcohol and carbonic acid gas, though 
traces of several other substances are simultaneously produced. 
{Vide " Fousel Oil" in Index.) By this reaction are formed the 
spirits of the various kinds of wine, beer, and liqueurs, such as 
Orange Wine {Vinum Aurantii, B. P.), made "by the fermenta- 
tion of a saccharine solution, to which the fresh peel of the bitter 
orange has been added ;" Sherry Wine {Vinum Xericum, B. P.), the 
fermented juice of the grape ; "Whiskey {Spiritus Frumenti, U. S. 
P.), containing from 48 to 56 per cent, of pure alcohol ; Bay Rum, 
or Spirit of Myrcia {Spiritus Myrcio?, U. S. P.), prepared by distill- 
ing rum with leaves of Myrcia acris ; and others. 

Alcoholic drinks vary much in strength. Cider or apple wine, 
perry or pear wine, and good beer (ale and porter or stout) contain 
4 to 6 per cent, of real alcohol; good light wines, both "red" and 
"white," and natural sherry also, 10 to 12 per cent. 5 strong sherry 
and port, which are commonly "fortified" — that is, contain added 
spirit — 16 or 18 per cent.; while "spirits" (gin, rum, brandy, 
whiskey, etc.) and "liqueurs" (ratafia, almond-flavored; mara- 
schino, cherry-flavored ; curaeoa, orange-flavored ; chartreuse, a 
composite flavored liqueur, etc.) are " under-proof " or "over- 
proof," terms explained in a following paragraph. The well- 
known effects of these spirituous fluids on the animal system 
would appear to be due primarily to alcohol, and secondarily to 
ethereal derivatives of alcohols. Some owe a part of their effect 
to non-volatile substances, for beer from which all alcohol, etc. 
has been removed by ebullition still has a powerful influence on 
the human economy. 

The official (U. S. P.) wines are all made with " Stronger White 
Wine" {Vinum Album Fortius, U. S. P.), made by adding 1 part 
of alcohol to 7 parts of "white wine" {Vinum Album, U. S. P.), 
the latter a kind of natural sherry containing not less than 10 or 
more than 12 per cent, of absolute alcohol. Vinum Eubrum, U. S. 
P., is of similar strength — a kind of natural port wine. 

Varieties of Alcohol. — The weak spirit, concentrated by distilla- 
tion till it contains 84 per cent, by weight of pure alcohol, is an 
ordinary article of trade ; its specific gravity at 60° F. is 0.8382. 
This is common Spirit of Wine, the Spiritus Rectificatus of the 
British Pharmacopoeia. The British official Proof Spirit* [Spiritus 

* Proof spirit is so termed from the fact that in olden times a proof 
of its strength was supposed to be afforded by moistening a small quan- 
tity of gunpowder and setting light to the spirit ; if it fired the pow- 
der, it was said to be "over-proof;" if not, " under-proof." The weak- 
est spirit that would stand this test was what we should now describe as 
of sp. gr. 0.920. 



VARIETIES OF ALCOHOL. 437 

Tenuior, B. P.) contains 49^ per cent, by weight, 57 by volume, of 
alcohol, and is made by diluting 100 volumes of " Rectified Spirit" 1 
with water until the well-stirred product measures 156 volumes. 
Sixty volumes of water will be required for this purpose, the liquids 
occupying less bulk after than before admixture. In the language 
of the Excise authorities, the rectified spirit of the Pharmacopoeia 
would be described as " 56 per cent, over-proof" (56 per cent. 0. P.) ; 
that is, 100 volumes contain as much alcohol as is present in 156 
volumes of proof spirit. Obviously, proof spirit may be made by 
diluting with water rectified spirit of any other strength than that 
mentioned above. Thus 100 fluidounces of a spirit of " seventy 
over-proof" may be diluted to 170, or the same quantity of a spirit 
of "fifty over-proof" may be diluted to 150, and so on. The spe- 
cific gravity of proof spirit at 60° P. is 0.920. Spirit 10 per cent, 
"under-proof" contains as much alcohol as would be present in 
spirit formed of 90 volumes of proof spirit mixed with sufficient 
water to form 100 volumes. According to British law, gin is not 
"adulterated" with water if it is not weaker than 35 degrees under- 
proof; nor brandy, whiskey, or rum if they are not weaker than 
25 degrees under proof. 

Alcohol, U. S. P., contains 91 per cent, by weight (94 by volume) •, 
Alcohol Diliihim, U. S. P., 45J per cent, by weight (53 by volume), of 
real alcohol, the remainder being water. The former has a sp. gr. 
of 0.820, the latter 0.928, at 15.6 C, or 0.812 and 0.920 respectively 
at 25° C. The stronger boils at 78° O. 

Absolute or real alcohol, C 2 II 3 (OH), may be prepared from spirit 
of wine by removing the water which the latter contains. This is 
accomplished partially by anhydrous carbonate of potassium, and 
finally and entirely by recently fused chloride of calcium. In 
operating on, say, one pint, 2 ounces of dried carbonate of potas- 
sium are placed in a bottle that can be well closed, and frequently 
shaken during two days with the spirit. Meanwhile put rather 
more than a pound of chloride of calcium into a covered crucible, 
and subject it to a red heat for half an hour ; then pour the fused 
salt on a clean stone slab, cover it quickly with an inverted porce- 
lain dish, and when it has congealed break it up into small frag- 
ments and enclose it in a dry stoppered bottle. Put one pound of 
this fused chloride of calcium into a flask, pour over it the spirit 
decanted from the carbonate of potassium, and, closing the mouth 
of the flask with a cork, shake them together and allow them to 
stand for twenty-four hours with repeated agitation. Then, attach- 
ing a dry condenser closely connected with a receiver from which 
free access of air is excluded, and applying the flame of a lamp to 
the flask, distil about two fluidounces, which should be returned to 
the flask, after which the distillation is to be continued until fifteen 
fluidounces have been recovered. The foregoing details are those 
of the British Pharmacopoeia. The product should be " colorless 
and free from empyreumatic odor. Specific gravity, from 0.797 to 
0.800, and therefore containing 1 or at most 2 per cent, of water. 
It is entirely volatilized by heat, is not rendered turbid when mixed 
with water, does not cause anhydrous sulphate of copper to assume 
37* 



438 ORGANIC CHEMISTRY. 

a blue color even after the two have been well shaken together." 
What little remains may, if necessary, be removed by the cautious 
addition of a little metallic sodium. If 5 per cent, of sodium be 
used, solution of ethylate of sodium or caustic alcohol results 
{Liquor Sodii Ethylatis, B. P.) by replacement of the hydrogen 
in the hydroxyl group of sodium. 

Na 2 + 2C 2 H 5 OII = 2C 2 H 5 ONa + H 2 . 

The solution contains 19 per cent, of ethylate of sodium. 

Spirit of French Wine (Spiritus Yini Gallici, U. S. P.) or Brandy, 
is a colored and flavored variety of alcohol distilled from French 
wine. Its color is that of light sherry, and is derived from the cask 
in. which it has been kept, but it is commonly deepened by the addi- 
tion of burnt sugar. Its taste is due to the volatile flavoring con- 
stituent of the Avine, often increased by the addition of artificial 
essences. " Brandy has a pale amber color, a distinctive taste and 
odor, and a sp. gr. not above 0.941 nor below 0.925, corresponding 
approximately with an alcoholic strength of 39 to 47 per cent, by 
weight or 46 to 55 per cent, by volume. If 100 c.c. of brandy be 
slowly evaporated in a weighed capsule on a water-bath, the last 
portions volatilized should have an agreeable odor, free from harsh- 
ness (abs. of fusel oil from grain or potato spirit). The residue, 
dried at 100° C. (212° ¥.), should weigh not more than 0.250 gm., 
equivalent to 0.25 per cent. (abs. of an undue amount of solids). 
This residue should have no sweet or distinctly spicy taste (abs. of 
added sugar, glycerin, or spices). It should nearly all dissolve in 
10 c.c. of cold water, forming a solution which is colored light green 
by a dilute solution of ferric chloride (traces of oak tannin from 
casks). 100 c.c. of brandy should be rendered distinctly alkaline to 
litmus by 3 c.c. of the volumetric solution of soda (abs. of an undue 
amount of free acid)."' — U. S. P. 

The foregoing words are also used in describing Whiskey (Spiritus 
Frumenti) in the United States Pharmacopoeia, except that the sp. gr. 
is to be "not above 0.930 nor below 0.917, corresponding approx- 
imately with an alcoholic strength of 44 to 50 per cent, by weight, 
or 50 to 58 per cent, by volume,*' and that the acidity is not to be 
greater in 100 c.c. than 2 c.c. of soda solution will neutralize. 

Tests. — There are no specific tests for alcohol when mixed with 
complex matters. It is, however, easily isolated and concentrated 
by fractional distillation, and is then recognizable by conjoint phys- 
ical and chemical characters. Thus its odor and taste are charac- 
teristic ; it is lighter than water, volatile, colorless, and, when tol- 
erably strong, inflammable, burning with an almost non-luminous 
flame ; it readily yields aldehyde (see below) and acetic ether (vide 
Index), each of which has a characteristic odor ; and, in presence of 
hot acid, alcohol reduces red chromate of potassium to a green salt 
of chromium. 

According to Lieben, 1 of alcohol in 2000 of water can be detected 
by adding to some of the warmed liquid a little iodine, a few drops 
of solution of soda, again warming gently, and setting aside for a 
time ; a yellowish crystalline deposit of iodoform (CIII,) is obtained. 



ALCOHOLS AND ETHERS. 439 

Under the microscope the latter presents the appearance of hex- 
agonal plates or six-rayed and other varieties of stellate crystals. 

C 2 H 6 + 4I 2 + 6NaHO = CHI 3 + NaCH0 2 + 5NaI + 5H 2 0. 

Other alcohols, aldehydes, gum, turpentine, sugar, and several other 
substances give a similar reaction. 

Tests of Purity. — Oil or resin is precipitated on diluting spirit of 
wine with distilled water, giving an opalescent appearance to the 
mixture. The specific gravity should be 0.838. Fusel oil, aldehyde, 
and such impurities are detected by nitrate of silver. ( Vide Index, 
"Alcohol, test for purity of.") Water in absolute alcohol may be 
detected by adding to a small quantity a little highly-dried sulphate 
of copper, which becomes blue (CuS0 4 ,5H 2 0) if water is present, 
but retains its yellowish-white anhydrous character (CuS0 4 ) if water 
be absent. 

Note. — Most ethyl derivatives are formed from alcohol, such as 
the nitrite of ethyl in spirit of nitrous ether, iodoethane, etc. These 
have been treated under "Ethane." Aldehyde and acetic acid are 
obtained from alcohol by oxidation. 



Alcohols and Ethers. — Just as such elementary radicals as potas- 
sium (K) form hydrates (as KOH) and oxides (as K 2 0), so do such 
compound radicals as ethyl (C 2 H 5 ) form hydrates (as common alco- 
hol, C 2 H 5 OH, and other alcohols) and oxides (as common ether, 
(C 2 H 5 ) 2 0, and other ethers). 

Sulphur Alcohols, CH 3 SH, C 2 H 5 SH, etc., analogous to sulphydrates, 
KIIS, etc., are known. They originally were termed mercapians 
(mercurius captans) from the readiness with which they took mer- 
cury captive (C 2 H 5 S) 2 Hg. Sulphur Ethers also are known, (CH 8 ) 2 S, 
(C 2 H 5 ) 2 S, etc. The vapors of such sulphur compounds have an ex- 
tremely unpleasant smell. 

Sulphonic Acids are the products of the oxidation of sulphur alco- 
hols. For example, 

2C 2 H 5 SH + 30 2 = 2C ? H 5 .S0 2 .OH 

Ethyl-mercaptan. Oxygen. Ethyl-sulphouic acid. 

They also may be formed by acting on hydrocarbons with sulphuric 
acid. Examples : 

SO *<OII + C « H « = SO *<OH 5 + H *° 

Sulphuric acid. Benzene. Benzene-sulphonic acid. Water. 

SO '<OII + C e H 5 CH s = S0 2 <£]^ CIT 3 + TT,0 

Sulphuric acid. Toluene. Toluene-sulphonic acid. Water. 

Sulphonic acids are isomeric with acid sulphites. Orthophenol- 
sulphonic acid, C 6 1T 4 0TI.S0. 2 .01I, sozolic acid, or aseptol, is a non- 
poisonous, non-irritating antiseptic. 

Saccharin, which is a harmless, non-alimentary, purely sweeten- 
ing agent, two or three hundred times as sweet as sugar, is benzoyl- 



440 



ORGANIC CHEMISTRY. 



sulphonic imide. Fahlberg obtains it by converting the toluene, 
C 6 H 5 CH 3 , of coal tar into toluene-sulphonic acid (above) ; this into 
a calcium salt, then into a sodium salt, and the latter into toluene- 
sulphonic chloride by action of trichloride of phosphorus and chlo- 
rine ; the liquid ortho-chloride into amide by ammonium carbonate : 
the amide is then oxidized by potassium permanganate to sulpham- 
idobenzoate and water ; hydrochloric acid then precipitating ben- 
zoyl-sulphonic imide or saccharin with elimination of water. " Sol- 
uble saccharin" is saccharin in which hydrogen is displaced by so- 
dium. The following formulas illustrate the stages of manufacture : 

^C 6 H 4 CH a 
-NH 2 



en ^^"-iCHg 



<?n ^C 6 H 4 COOK 
SU 2< N h 2 

Sulphamidobenzoate 
of potassium. 



S0 2 <^ H4CH3 

Toluene-sulphonic 
chloride. 

SO <T C 6 H 4 CO 



S0 2 < 






Sulphonyl, a new hypnotic, is a crystalline, colorless, inodorous, taste- 
less substance, a product of the action of permanganate solution on 
mercaptol — a liquid resulting from the reaction of hydrochloric acid, 
mercaptan, and acetone. Its descriptive name is dietnylsulphondime- 
thyl-methane, and the following is its descriptive formula : 



CH. 

ch; 



>c< 



S0 2 CH 5 
S0 2 CH 5 



ETHER. 

Experimental Process. — Into a capacious test-tube put a small 
quantity of spirit of wine and about half its bulk of sulphuric acid, 



Fig. 41 




Preparation of Ether. 

mix, and gently warm ; the vapor of ether, recognized by its odor, 
is evolved. Adapt a cork and long bent tube to the test-tube, 



ETHER. 441 

and slowly distil over the ether into another test-tube. Half the 
original quantity of alcohol now placed in the generating-tube will 
again give ether ; and this operation may be repeated many times. 

On the larger scale, and according to the following official process 
(yEther, B. P. ), the addition of alcohol, instead of being intermit- 
ting, is continuous, a tube conveying alcohol from a reservoir into 
the generating-vessel. Mix ten fluidounces of sulphuric acid with 
twelve fluidounces of rectified spirit in a glass retort or flask capable 
of containing at least two pints, and, not allowing the mixture to 
cool, connect the retort or flask, by means of a bent glass tube, with 
a Liebig's condenser, and distil with a heat sufficient to maintain the 
liquid in brisk ebullition. (If a thermometer also be inserted in the 
tubulure of the retort or through the cork of the flask, the tempera- 
ture may be still more carefully regulated — between 284° and 290° 
F.) As soon as the ethereal fluid begins to pass over supply fresh 
spirit in a continuous stream, and in such quantity as to about equal 
the volume of the fluid which distils. For this purpose use a tube 
furnished with a stopcock to regulate the supply, as shown in Fig. 
49, connecting one end of the tube with a vessel containing the spirit 
supported above the level of the retort or flask, and passing the other 
end through the cork of the retort or flask into the liquid. When a 
total of fifty fluidounces of spirit has been added and forty-two fluid- 
ounces of ether have distilled over, the. process may be stopped. 

To "partially purify the liquid, dissolve ten ounces of chloride 
of calcium in thirteen ounces of water, add half an ounce of lime, 
and agitate the mixture in a bottle with the impure ether. Leave 
the mixture at rest for ten minutes, pour off the light supernatant 
fluid, and- distil it with a gentle heat until a glass bead of specific 
gravity 0.735 placed in the receiver begins to float. The ether and 
spirit retained by the chloride of calcium and by the residue of each 
rectification may be recovered by distillation and used in a subse- 
quent operation. 

Explanation of Process. — On the addition of sulphuric acid to 
alcohol in equal volumes, one molecule of each reacts and gives a 
molecule of ethylhydrogen sulphate and one of water : — 



C 2 H,OH 


+ H,,SO + - 


= C 2 H 5 TIS0 4 


+ 


11,0 


Alcohol. 


Sulphuric 
acid. 


Ethylhydrogen 
sulphate. 




Water 



More alcohol then gives ether and sulphuric acid by the reaction of 
one molecule of the alcohol on one of ethylhydrogen sulphate (some- 
times termed ethylsulphuric acid or sulphethylic acid or sulphovinic 
acid) : — 

C,TT 5 OTI + C.,IIJIS0 4 = (C 2 H 5 ) 2 = H 2 S0 4 

Alcohol. Ethylhydrogen Ether. Sulphuric 

sulphate. acid. 

The water of the first reaction and the ether of the second distil over. 
while the sulphuric acid liberated is attacked by alcohol and recon- 
verted into ethylhydrogen sulphate; so that the sulphuric acid orig- 
inally employed finally remains in the retort in the form of ethyl- 



442 ORGANIC CHEMISTRY. 

hydrogen sulphate. The effect, however, of a small quantity of sul- 
phuric acid in thus converting a large quantity of alcohol into ether 
is limited, secondary reactions occurring to some extent after a 
time. 

Properties. — Pure ether is gaseous at temperatures above 95° F. ; 
hence the condensing-tubes employed in its distillation must be kept 
as cool as possible. At all ordinary temperatures it rapidly volatil- 
izes, absorbing much heat from the surface on which it is placed. A 
few drops evaporated consecutively from the back of the hand pro- 
duce great cold, and if blown in the form of spray the cooling effect 
is so rapid and intense as to produce local anaesthesia. Evaporated 
by aid of a current of air from the outside of a thin narrow test- 
tube containing water, the latter is solidified to ice. Its vapor is 
very heavy, more than twice and a half that of air and nearly forty 
times that of hydrogen (H 2 = 2 : C 4 H ]0 O = 74 ; or as 1 to 37). In a 
still atmosphere, therefore, it will flow a considerable distance along 
a table or floor before complete diffusion occurs ; the vapor is also 
highly inflammable ; hence the importance of keeping candle and 
other flames at a distance during manipulations with ether. Exposed 
to the action of air and light, ether gives rise to ozone. 

Purification. — To imitate the process of partial purification above 
described, add to the small quantity of ether obtained in the forego- 
ing operation a strong solution of chloride of calcium and a little 
slaked lime ; the latter absorbs any sulphurous acid that may have 
been produced by secondary decompositions, while the former 
absorbs water ; on shaking the mixture and then setting aside for a 
minute or two, the ether will be found floating on the surface of the 
solution of chloride of calcium. 

This ether, redistilled until the distillate has a sp. gr. not higher than 
0.735, and boiling-point not higher than 105° F., is the ether of the 
British Pharmacopoeia. It still contains about 8 per cent, of alcohol. 
The latter may be removed by well shaking the ether with half of 
its bulk of water, setting aside, separating the floating ether, and 
again shaking it with water ; alcohol is thus washed out. This washed 
ether containing water (for water and ether are to some extent solu- 
ble the one in the other ; fifty measures of pure ether agitated 
with an equal volume of water are reduced to forty-five measure*) is 
placed in a retort with solid chloride of calcium and a little caustic 
lime, and once more distilled ; pure dry ether results. Sp. gr. not 
exceeding 0.720. JEther, U. S. P., contains nearly 74 per cent, of 
real ether, nearly 26 per cent, of alcohol, and a little water ; sp. gr. 
0.750 at 15° C. JEther Portior, U . S. P., contains nearly 94 per 
cent, of real ether, nearly 6 per cent, of alcohol, and a little water ; 
sp. gr. not above 0.725 at 15° C. or 0.716 at 26° C. ; boiling-point, 
37° C. Agitated with an equal volume of glycerin, the JEther should 
yield 75 per cent, of ether, while JEther Portior should yield 86 per 
cent. 

Spiritus JEtheris. U. S. P., is a mixture of 30 weights of stronger 
ether with 70 similar weights of alcohol. Spiritus JEtheris Com- 
positus, U. S. P., contains 30 of stronger ether, 67 of alcohol, and 
3 of ethereal oil. It is the old " Hoffmann's Anodyne." 



ALCOHOLS. 443 

ALCOHOLS (continued). 
Propylic and Butylic Alcohols. 

The primary and secondary propyl alcohols (C 2 H 5 CH 2 OH, and 
CII 3 CH 3 CHOH) and the four butyl alcohols (C 4 H 9 OH ; see below) 
are of no special pharmaceutical interest. 

CH 2 — CH 2 — CH 3 CH<™ 3 CH 2 — CH 3 CH 3 

I I L 3 I I 

H— C— OH H— C— OH CH 3 — C— OH CH 3 — C— OH 

I III 

II H II CH 3 

Primary Primary Secondary Tertiary 

normal butyl iso-butyl butyl butyl 

alcohol. alcohol. alcohol. alcohol. 

Amylic Alcohol. 

Pentylic or Amylic Alcohol (Fousel oil), (Alcohol Amylicmn, B. P.) 
(C 5 H n HO or C 4 H 9 CH 2 OH), is a constant accompaniment of ethylic 
or common alcohol (C 2 H 5 HO), especially when the latter is prepared 
from sugar which has been derived from starch ; hence the name, 
from amylum, starch. The sugar of potato-starch yields a consider- 
able quantity ; hence the alcohol is often callen potato oil. It is also 
termed fousel oil or fusel oil (from (j>vo, phuo, I produce), in allusion 
to the circumstance that the supposed oil is not simply educed from 
a substance already containing it, as is usually the case with oils, but 
is actually produced during the operation. It was described as oil 
probably because it resembled oil in not readily mixing with water ; 
but it is soluble to some extent in water, and is a true spirit, homol- 
ogous with the spirit of wine. It often contains variable proportions 
of propylic, butylic, and caproylic alcohols. (See also Valerianic 
Acid.) When used for medicinal purposes "it should be redistilled, 
and the product, passing over at 262° to 270° F. (or about 128° to 
132° C), be alone collected for use." 

Amylic alcohol is "a colorless liquid, with a penetrating and 
oppressive odor and a burning taste. When pure its specific gravity 
is .818. Sparingly soluble in water, but soluble in all proportions 
in alcohol, ether, and the essential oils. Exposed to the air in con- 
tact with platinum-black, it is slowly oxidized, yielding valerianic 
acid" (C 4 H 9 .COOH). Two alio tropic varieties of amylic alcohol 
exist — one, a, having no action on, the other, /?, lsevo-rotating, a 
polarized ray. The amylic alcohol of trade probably contains both 
varieties. 

CH 2 ~CH<™3 CH<^-CH 8 

II— C— OH II— C— on CII— c— on 

I I 'I 

H II C a H 6 

Primary Primary Tertiary 

a or inactive or active amylic alcohol, 

amylic alcohol. amylic alcohol? " aim leue hydrate," 



444 ORGANIC CHEMISTRY. 

The constitution of the variety of amylic alcohol, C 5 H n OH, known 
as tertiary amylic alcohol or dimethyl-ethyl-carbinol, is shown in the 
above graphic formula. It is used in medicine for hypnotic purposes 
in place of chloral hydrate, and is known as amylene hydrate, for it 
contains the elements of amylene, C 5 H 10 , and water, H 2 0. 

The pentylic salts of pharmaceutical interest are all derived from 
amylic alcohol. 

Other Monhydroxyl Alcohols. 

Among the higher alcohols are the following : — 

Cetylic Alcohol (C 16 H 33 OH), or Hydrate of Cetyl, formerly termed 
ethal, obtained by saponifying spermaceti (Cetaceum, U. S. P.), which 
consists of palmitate of cetyl (C 16 H 33 C 16 H 31 2 ), or cetine. Sperma- 
ceti is the solid crystalline fat accompanying sperm oil in the head 
of the spermaceti whale. Sp. gr. about 0.945 : melting-point near 
50° C. 

Cerylic Alcohol (C 27 H 55 OH) is obtained in a similar manner from 
Chinese wax (ceryl-cerolate). 

Melissic Alcohol (C 30 H 61 OH) is obtained in a similar manner from 
melissic palmitate, the portion of beeswax soluble in hot alcohol. 
Yellow Wax [Cera Flava, U. S. P.), and the same bleached by 
exposure to moisture, air, and sunlight, or White Wax (Cera Alba, 
U. S. P.), is the prepared honeycomb of the hive-bee. According to 
Brodie, it is in the main a mixture of the alcohol just named with 
cerotic acid (C 26 H 53 COOH) and about 5 per cent, of ceroleine, the 
body to which the color, odor, and tenacity of wax are due. Amongst 
the possible adulterants of wax are paraffin and ceresine. The latter 
is the purified native ozokerite of Galicia, a solid hydrocarbon, 
largely used as a substitute for beeswax, especially in Russia. Both 
paraffin and ceresine reduce the melting-point of wax, which should 
not be lower than 146° F. (63.3° C. ) when taken in the manner 
described in connection with the quantitative determination of tem- 
perature (vide Index). The amount is obtained by destroying the 
wax with warm oil of vitriol, and afterward with fuming sulphuric 
acid, which scarcely affects paraffin and ceresine. Pure wax will not 
yield more than about 3 per cent, to cold rectified spirit, whereas 
rosin, etc. would be extracted by the spirit. Solution of soda 
extracts nothing from pure wax, but dissolves fat acids, fats, rosin, 
Japan wax, etc., and the alkaline fluid then yields a precipitate of 
acids on the addition of hydrochloric acid. Soap would be dissolved 
from wax on boiling the sample with water, and the aqueous fluid 
would yield oily acid on adding hydrochloric acid. Flour or any 
starch would be detected in the cooled aqueous fluid by iodine. 



The Allylic Series of Alcohols (^H^OH) (monhydric alcohols). 
— Allylic Alcohol (C 3 ll 5 OH) may be obtained by heating 4 parts of 
glycerin with one of oxalic acid, the receiver being changed at 195° 
C., and the liquid collected till the temperature rises to 260° C. The 
first product is formic acid, which reacts on glycerin, forming mono- 



formin 



MONOHYDROXYL ALCOHOLS. 445 

C 3 H 5 (OH) 3 + HCOOH = OH 2 + C 3 H 5 (OH) 2 (H.COO). 

Glycerin. Formic acid. Monoformin. 

This, on further heating, yields allylic alcohol, 

C 3 H 3 (OH) 2 H.COO = H 2 + C0 2 + C 3 H 5 OH. 
By the action of the haloid acids it produces iodine, bromine, and 
chlorine derivatives, by replacing the (OH) by I, Br, or CI 5 these 
derivatives, when digested with potassium sulphocyanate, yield allyl 
sulphocyanate or artificial Oil of Mustard (identical in composition 
with the chief constituent of the natural oil), the sulphocyanate of 
allyl being the body to which mustard owes its power of inducing 
inflammatory action on the skin ("Mustard Poultice" and Charta 
Sinapis, U. S. P.). 

Mustard {Sinapis, U. S. P.) is a powdered mixture of black or, 
rather, reddish-brown mustard-seeds from the Brassica nigra, and 
white mustard-seeds from the Brassica Alba. The white mustard- 
seed contains sinalbin (C 30 H 44 N 2 S 2 O 16 ), a glucoside which, in contact 
with the myrosin in an aqueous extract of mustard, yields the sulpho- 
cyanate of the radical acrinyl, a body which forms part of the essen- 
tial oil of mustard paste. 

C 30 H 44 N 2 S 2 O 16 = C 7 H 7 OCNS + C 16 H 24 5 NSHS0 4 + C 5 H ]2 6 

Sinalbin. Sulphocyanate Acid sulphate Glucose, 

of acrinyl. of sinapisine. 

The black contains the albumenoid ferment, myrosin, resembling the 
emulsin of almonds, and also myronate of potassium, or sinigrin. 
The latter is the body which, under the influence of the former, 
yields the chief part of the pungent oil of mustard paste. The 
amount of myrosin in black mustard is scarcely sufficient to decom- 
pose tho whole of the sinigrin, while in white mustard the amount is 
more than sufficient to decompose sinalbin. Hence the most effective 
mustard is a mixture of white and black. 

The ferments act most effectively, and therefore the maximum 
amount of pungency is produced in mustard paste at low tempera- 
tures, not exceeding 100° F. 

KC 10 H 18 NS 2 O 10 = KHSO, + C,II 5 CNS + C 6 H 12 6 

Myronate of Acid sulphate Sulphucyanate Glucose, 

potassium. of potassium. of allyl. 

Crude oil of mustard often contains cyanide of allyl, C 3 H 5 CN. 

In the Pharmacopoeia of India the seed of Sinapis juncea, Bat, or 
Indian Mustard Plant, is official in addition to that of S. alba and & 
nigra. It is the common mustard of warm countries. It does not 
differ chemically from other mustard. Allyl compounds are also 
met with in several other cruciferous and liliaceous plants. Oil of 
garlic {Allium, U. S. P.) owes its odor to a sulphide of allyl (C S H 5 ) 2 S, 
which may be artificially obtained by acting on allyl iodide by 
potassium sulphide : — 

2C 3 H 5 I + K 2 S = (C.,ir 5 ) 2 S + 2KI 

Iodide of allyl. Potassium sulphide. Sulphide of allyl. Iodide of potassium, 

Deq/lene Alcohol, C 10 H 19 OH, belongs to this series. Menthol 
{Menthol, B. P.), obtained from oil of peppermint, is said by some 
to consist wholly of this alcohol. 
38 



446 ORGANIC CHEMISTRY. 

QUESTIONS AND EXERCISES. 

724. Give an outline of the relations between alcohols and acids. 

725. Give a general method of preparing the primary alcohols of 
the ethylic series. 

726. Name the source of methylic alcohol. 

727. What is " methylated spirit" ? 

728. Describe the method by which methylated spirit is detected 
in a tincture. 

729. How can artificial ethylic alcohol be prepared ? 

730. Write a few sentences on the formation, purification, and 
concentration of alcohol, and explain the difference between rectified 
spirit, proof spirit, and absolute alcohol. 

731. What quantity of water must be added to one gallon of spirit 
of wine 56 degrees over-proof to convert it into proof spirit ? 

732. To what volume must 5 pints of spirit of wine of 53 degrees 
over-proof be diluted before it becomes proof spirit? 

Ans. 7 pints 13 ounces. 

733. State the specific gravity of proof spirit. 

734. State the proportion of alcohol commonly present in malt 
liquors, light wines, port and sherry, and "spirits," and state the 
extent to which spirits may be diluted without " adulteration." 

735. Enumerate the characters of alcohol. 

736. Whence is brandy obtained? and to what are due its color 
and flavor? 

737. Describe the official process for the preparation of ether, giv- 
ing equations. 

738. Offer a physical explanation of the mode of producing local 
anaesthesia. 

739. How is commercial ether purified? 

740. Is "amylic alcohol" a simple or complex body? 

741. How is ally lie alcohol prepared? In what relation does 
ally lie alcohol stand to oil of mustard and oil of garlic ? 



Alcohols of the C u H 2n _ 7 OH Series. Phenols and Benzylic Alco- 
hols. 

Carbolic Acid. 

Phenol, Phenic Alcohol, Phenic Acid, or Carbolic Acid* 

(C 6 H 5 OH) may be artificially obtained by heating benzene with 

sulphuric acid, which forms benzene (page 446) sulphonic acid 

(C 6 H 5 HS0 3 ) ; this, when heated with potash, yielding the phenol : — 

C 6 H 5 HS0 3 + KHO + C 6 H 5 OH -f KHS0 3 . 

Benzene Potassium Phenol. Acid sulphite 

sulphonic acid. hydrate. of potassium. 

Commercially, carbolic acid is obtained from that part of coal tar 
boiling between 180° and 190° C. When purified it is a colorless f 

* Ordinary carbolic acid is a mixture of phenol, cresol, and other 
homologues. 

f Phenol soon assumes a pink color, probably owing to the formation 
of aurin (C 19 H u 3 ) or rosolic acid (C 20 H lti O 3 ) by absorption of carbonic 
acid and oxygen. 



CARBOLIC ACID. 447 



crystalline body {Acidum Carbolicum, U. S. P.). A crystalline, 
so-called hydrous acid (C 6 H 5 OH.H 2 0) may also be obtained. 

At temperatures above 95° F. ordinary carbolic acid is an oily 
liquid. It is only slightly soluble in water, but readily dissolved 
by alcohol, ether, and glycerin (Glycerinum Acidi Carbolici, B. P.). 
In odor, taste, and solubility (and in appearance when liquefied by 
heat or by the addition of 5 to 10 per cent, of water) it resembles 
creasote, a wood-tar product for which carbolic acid has been substi- 
tuted. Besides phenol (C fi H 5 OH), coal-tar oil contains cresol, cresylic 
acid (C 7 H 7 OH), or (C 6 H 4 CII 8 OH), the alcohol of toluene, while wood- 
tar oil furnishes guaiacol (C 7 H 8 2 ), boiling-point 200° C. — also a 
product of the destructive distillation of guaiacum resin — and crea- 
sul (C 8 H 10 O 2 ) or creasote. Certain coloring-matters may be obtained 
by the oxidation of carbolic acid ; ammonia or, still better, phenyl- 
ammonia (aniline or phenylamine) mixed with it, and then a small 
quantity of solution of a hypochlorite, gives a blue liquid. No 
very satisfactory chemical method can be found for distinguishing 
creasote from carbolic acid, as creasote contains phenol, the chief 
difference consisting in the fact that the former boils only at 370 F., 
while the latter readily dries up at 212°. Some other physical dif- 
ferences exist : thus, carbolic acid does not affect a ray of polarized 
light •, creasote twists it slightly to the right. Carbolic acid is either 
solid or may be may be solidified by cooling : creasote is not solid- 
ified by the cold produced by a mixture of hydrochloric acid and 
sulphate of sodium. Creasote from coal (impure or crude carbolic 
acid) gives a jelly when shaken with albumen or with collodion ; 
creasote from wood (Creasotum, U. S. P.) is scarcely affected, especi- 
ally if quite free from even all natural traces of carbolic acid. Coai 
creasote is soluble in solution of potash and in the strongest solution 
of ammonia (Read), wood creasote scarcely soluble. The coal prod- 
uct is soluble in twenty volumes of water, and a neutral solution of 
ferric chloride strikes a more or less permanent green or blue color 
with the liquid ; wood creasote is less soluble {Aqua Creasoti, U. S. 
P., is said to contain 1 in 129), and not permanently colored blue by 
ferric chloride. An alcoholic solution of the coal oil is colored 
brown by ferric chloride ; a similar solution of true creasote green. 
A dilute solution of creasote, such as creasote-water, is not affected 
by agitation with spirit of nitrous ether, while a similar solution of 
phenol becomes red. A few drops of the spirit of nitrous ether are 
placed in a test-tube, then about a drachm of the aqueous fluid and 
an equal volume of sulphuric acid are poured down the sides of the 
tube. A pink or red color results if phenol be present, especially 
after standing aside a short time (Eykman ; MacEwan). A solution 
of carbolic acid gives with excess of bromine-water an insoluble 
white precipitate of tribromo-phenol, C 6 H 2 Br 3 OH. This reaction is 
useful in quantitatfve estimations of carbolic acid. According to 
Mr. Thomas Morson, pure creasote is unaffected when mixed with 
an equal volume of commercial glycerin, while carbolic acid is mis- 
cible in all proportions, and will carry into solution even a consider- 
able quantity of creasote. 

Carbolic acid and alkalies yield carbolates or phenylates^ as 



448 ORGANIC CHEMISTRY. 

C 6 H 5 0K.C 6 H 5 0Na. Alcoholic solutions of thQ latter and of mer- 
curic chloride yield yellow crystalline mercuric phenylate, or 
phenolmercury , (C 6 H 5 0) 2 Hg. 

Carbolic acid is a powerful antiseptic (avri, anti, against, and ut/ttcj, 
sepo, I putrefy). In large doses it is poisonous, antidotes being a mix- 
ture of olive oil and castor oil, freely administered, or a mixture of 
slaked lime, with about three times its weight of sugar rubbed together 
with a little water. Carbolic acid is soluble in oil of vitriol, sulpho- 
carbolic acid, phenol sulphonic acid (C 6 H 4 (OH)S0 3 H), or sidpho- 
phenic acid being formed. On diluting and mixing with oxides, 
hydrates, or carbonates sulphocarbolates are formed. The formula 
of sulphocarbolate of sodium is NaC 6 H 5 S0 4 .2H 2 0, or C 6 H 4 (0H)S0 3 - 
Na.2H 2 0. It is obtained by saturating sulphocarbolic acid by car- 
bonate of barium, and decomposing the resulting soluble sulpho- 
carbolate of barium, (C 6 H 4 OHS0 3 ) 2 Ba, by carbonate of sodium 
until a precipitate of carbonate of barium ceases to form. The 
filtrate on evaporation yields colorless, neutral, prismatic crystals 
of the salt (Sodii Sidphocarbolas, U. S. P.). Sulphocarbolate of 
zinc, (C 6 H 4 OHS0 3 ) 2 Zn.H 2 {Zinci Sidphocarbolas, B. P.), may 
be obtained by saturating sulphocarbolic acid with oxide of zinc, 
(C 6 H 4 (OH)S0 3 ) 2 Zn. 

Trinitro-phenol (C 6 H 2 (X0 2 ) 3 0H) is formed on slowly dropping 
carbolic acid into fuming nitric acid ; it is the yellow dye known 
as carbazotic acid or picric acid ; most of the picrates are explosive 
by percussion. 

Both carbolic acid and benzene are secondary products, obtained 
in the manufacture of coal gas ; hence, indeed, the word phenic, and 
thence phenyl (from <paivu, phaino, I light, in allusion to the use of 
coal gas). 

Constitution of Phenol. — Phenol (C 6 H 5 0H) may be regarded as 
benzene (C fi II 6 ), in which one atom of hydrogen (H) is displaced by 
hydroxy 1 (OH). When two atoms of hydrogen in benzene are dis- 
placed by two of hydroxy 1, resorcin (C 6 H 4 20H) results, a colorless, 
crystalline antiseptic having many advantages over carbolic acid in 
surgical operations. Its name was given in allusion to its original 
source, resin, and to certain similarities with orcin. It occurs in 
white flat prisms readily soluble in most liquids. It may be made 
by passing benzol vapor into hot sulphuric acid, and heating the 
product (benzenedisulphonic acid, C 6 H 4 (S0 2 .0H) 2 ) with excess of 
soda. 

C 6 H 4 (S0 2 .Na0) 2 + 2NaII0 = C 6 H 4 (0H) 2 + 2Na 2 .S0 3 

Benzenedisulphonate Soda. Resorcin. Sulphite 

of sodium. of sodium. 

Resorcin is one of a group of three metameric dihydroxyl-ben- 
zenes. Their chemical relationships warrant the conclusion (on the 
atomic theory) that the cause of their differences in properties is a 
difference of position of the two atoms of hydroxyl in the molecule, 
these being, respectively, next to each other, separated by one atom 
(of CH) and by two atoms (of CH) (see Constitution of Benzene, 
p. 434), thus : 



RESORCIN — CRESOL. 449 

WHO) - C(HO) OTIO) 

[C C(IIO) HC CH HC CH 



Hi 



HC C(IIO) 

HC CH 

CH CH C(HO) 

Ortho-dihydroxyl- Meta-dihydroxyl- Para-dihydroxyl- 

benzene (pyrocatechin). benzene (resorcin). benzene (hydroquinone). 

By heating phenol with zinc dust benzene results, — 

C 6 H 5 OH + Zn = ZnO -f C 6 H 6 . 

Salicylic acid is now made from phenol. (Vide Salicylic Acid.) 

Cresol or Tolyl Alcohol, C 6 H 4 OH.CH 3 , one of the alcohols of tol- 
uene, C 6 H 5 CH 3 , is always found with crude phenol 5 artificially it 
may be made in the same manner as phenol, by acting on toluene 
with sulphuric acid and heating the resulting sulphonic acid 
(C 6 H 4 (S0 3 H)CH 3 ) with potash. With ferric chloride it gives a 
brown coloration. 

Benzylic Alcohol, Phenylcarbinol, C 6 H 5 CH 2 OH, is isomeric with 
cresol, but having the hydroxyl group replaced in the methane 
nucleus, and not in the benzene nucleus of toluene. Having the 
CH 2 OH group, on oxidation it yields benzoic aldehyde, C 6 H 5 COH 
(oil of bitter almonds), and benzoic acid, C 6 H 5 COOH. 



b. Dihydroxyl Derivatives of Hydrocarbons. 

Dihydric Alcohols — Glycols — C n H 2n (OH) 2 Series. — Glycols maybe 
viewed as dihydroxyl derivatives of the paraffins, the alcohols of 
the ethylic series being mono-derivatives : 

C 2 H 6 C 2 II 5 OH C 2 H 4 (OH) 2 

Etbane. Ethyl alcohol. Glycol. 

They are prepared by acting on di-iodo-derivatives of the paraffins 
by acetate of silver, and then treating with potash : 

C 2 HJ 2 + 2CH 3 COOAg = (CH ;5 COO) 2 C 2 H 4 + 2AgI 

Di-iodoethane. Acetate of Acetate of Iodide of 

silver. ethylene. silver. 

(CH 3 00.0) 2 C 2 H 4 + 2KHO = C 2 H 4 (OH) 2 + 2CH 8 .COOK 

Acetate of ethylene. Potash. Glycol. Acetate of potassium. 

The glycols yield very interesting results on oxidation, forming 
two sets of acids, the lactic and the succinic series. 

Aromatic Glycols, C n H 2n _8(OH) 2 , and Saligmin Alcohols. — For the 
dihydric alcohols of benzene — namely, resorcin, pyrocatechin, and 
hydroquinone — see Phenol. Toluene Dihydric Alcohols J— Orcin } 
C" ; l 1,(01 1),CH 3 . This is found in lichens.' Hydroxybmzt/lic Alco- 
hol, salicylic alcohol, saligenol, saligenin, C 6 H 4 OH.CH 2 OH, This 
is obtained from the salicin of willow-bark, Having the hydroxyl 



450 ORGANIC CHEMISTRY. 

group in the methane as well as in the benzene nucleus, salicvlic 
aldehyde (C 6 H 4 OH.COH) and salicylic acid (C 6 H 4 OILCOOH) are 
formed on oxidation. 



c. Trihydroxyl Derivatives of Hydrocarbons. 
Triliydric Alcohols. — C n H 2n 1 (OH) 3 Series — Glycerol. 

Glycerin. 

Glycerol * propenyl alcohol, glycerin, C 3 H 5 (OH) 3 . The propenyl 
(glycyl or glyceryl) of glycerin, in combination with many of the 
acidulous radicals of the acids, oleic, palmitic, stearic, etc., forms 
most of the solid fats and oils. When these latter substances are 
heated with metallic hydrates (even with water — hydrate of hydro- 
gen — at a temperature of 500° to 600° F.), double decomposition 
occurs, oleate, palmitate, or stearate of the metal is formed, and 
glycerol (propenylhydrate) is set free. Hence glycerin is a by-prod- 
uct in the manufacture of soap, hard candles, and lead plaster. 
{Vide Index.) 

Properties. — Glycerin is viscid when pure, specific gravity not 
below 1.25, U. S. P., has^a sweet taste, and is soluble in water or 
alcohol in all proportions. It has remarkable powers as a solvent, 
is a valuable antiseptic even when diluted with 10 parts of water, 
and is useful as an emollient. In vacuo it may be distilled un- 
changed, but under ordinary atmospheric pressure it is decomposed 
by heat, especially if distillation be attempted in a flask or retort. 
In a shallow open vessel heat readily vaporizes it. From damp air 
glycerin absorbs moisture slowly, but in considerable proportions. 
Perfectly pure and anhydrous glycerin, at a few degrees below the 
freezing-point of* water, sometimes solidifies to a mass of crystals. 

Tests. — Heat one or two drops of glycerin in a test-tube, 
alone or with strong sulphuric acid, acid sulphate of potas- 
sium, or other salt powerfully absorbent of water ; vapors of 
acrolein, acrylic aldehyde (from acer, sharp, and oleum, oil), are 
evolved — 

C 3 H 5 (OH) 3 = 2H,0 + CH 2 CH.COH 

Glycerol. Water. Acrylic aldehyde. 

— recognized by their powerfully irritating effects on the eyes 
and respiratory passages. If the glycerin be in solution, it 
must be evaporated as low as possible before applying this 
test. 

Add a few drops of the fluid suspected to contain the gly- 
cerin to a little powdered borax ; stir well together ; dip the 

* It will be noticed that all the alcohols have the termination -ol — 
carbinol, glycol, glycerol, saliginol, pyrogallol. 



FATTY BODIES. 451 

looped end of a platinum wire into the mixture, and expose 
to an air-gas flame ; a deep-green color is produced (Senier 
and Lowe). 

The glycerin liberates boric acid, and it is the latter which colors 
the flame. Ammoniacal salts, which similarly affect borax, must 
first be got rid of by boiling with solution of carbonate of sodium. 
Liquids containing much indefinite organic matter must sometimes 
be evaporated to dryness, the residue extracted by alcohol, and the 
latter tested for the glycerin. To detect traces, liquids must be con- 
centrated. 

Glycerin, by action of very strong nitric acid, yields nitroglycerin, 
a compound containing, in place of three atoms of hydrogen of the 
glycerin, three of N0 2 . It is highly explosive, a very small quan- 
tity being liable to explode during preparation, and to do great 
harm. 75 parts of nitroglycerin, absorbed by 25 of porous silica, 
yield a pasty mass more convenient to handle than nitroglycerin 
itself; it is used for blasting under the name of dynamite. Tablets 
of chocolate, weighing 2J grains and containing y^ grain of nitro- 
glycerin, constitute the Tabellce Nitroglycerin^ B. P. 

Besides glycerin itself ( Glycerinum, U. S. P.), solutions or mix- 
tures of starch and of yolk of egg and glycerin {Glycerinum Amyli, 
U. S. P., Glycerinum Vitelli or Glyconin, U. S. P.) are official. 

Fatty Bodies. 

Processes of Extraction. — Fixed oils and fats are extracted from 
animal and vegetable substances by pressure or straining with or 
without |he aid of heat, or by digestion in solvents, as ether, etc., 
and evaporation of the solvent. 

Constitution and General Relations. — Fixed oils and fats are. 
apparently, almost as simple in constitution as ordinary inorganic 
salts. Just as acetate of potassium (KC 2 H 3 2 ) is regarded as a com- 
pound of potassium (K) with the characteristic elements of all ace- 
tates (C 2 H 3 2 ), so soft soap is considered to be a compound of potas- 
sium (K) with the elements characteristic of all oleates (C 18 H 33 2 ), 
and hence is chemically termed oleate of potassium (KC 18 H 33 2 ). 
Olive oil {Oleum Olivai, U. S. P.), from which soap is commonly pre- 
pared, is mainly oleate of the trivalent radical glyceryl (C 3 H 5 ), the 
formula of pure fluid oil being C 3 H 5 3C I8 II 33 2 , and its name oleine. 
The formation of a soap therefore, on bringing together oil and a 
moist oxide or hydrate is a simple case of double decomposition (or, 
rather, metathesis), as seen already in connection with lead plaster 
(p. 245), or in the following equation relating to the formation of 
common hard soap : — 

3NaIIO + C 8 H 5 3C 18 H 33 O a = 3NaC 18 H 88 2 + 0,11,3110 

Hydrate of sodium Oleate of glyceryl Oleate of sodium Hydrate of glyceryl 

(caustic soda). (vegetable oil). (hard soap). (glyceric). 

Berthelot has succeeded in preparing oil artificially from the 

oleate of hydrogen, or oleic acid, HC 18 II. ,..().,. and glycerin : and it is 
said to be identical with the pure oleine of olive and oi' other fixed 



452 ORGANIC CHEMISTRY. 

oils. Hard fats chiefly consist of stearin — that is, of tristearate of 
glyceryl (C 3 H 5 3C 18 H 35 d 2 ). Mr. Wilson, of Price's Candle Company, 
obtains stearic and oleic acids and glycerin by simply passing steam, 
heated to 500° or 600° F., through melted fat. Both the glycerin 
and fat-acids distil over in the current of steam, the glycerin dissolv- 
ing in the condensed water, the fat-acids floating on the aqueous 
liquids. From oleate of glyceryl and hydrate of hydrogen there 
l-esult oleate of hydrogen and hydrate of glyceryl.* The oleic acid 
[Acidum Oleiciun, U. S. P.) is separated by cooling and pressing 
the mixture. It is "a straw-colored liquid, nearly odorless and 
tasteless, and with not more than a very faint acid reaction. Unduly 
exposed to. air, it becomes brown and decidedly acid. Specific 
gravity. 0.860 to 0.890. It is insoluble in water, but readily soluble 
in alcohol, chloroform, and ether. At 40° to 41° F. (4.5° to 5° C.) 
it becomes semi-solid, melting again at 56° to 60° F. (13.3° to 15.5° 
C). It should be completely saponified, when warmed, with carbon- 
ate of potassium, and an aqueous solution of this salt, neutralized 
by acetic acid and treated with acetate of lead, should yield a pre- 
cipitate which after washing with boiling water is almost entirely 
soluble in ether,' ' showing the absence of any important quantity of 
stearic and palmitic acids, the lead stearate and palmitate being 
insoluble in ether. 

In a mixture of oils and fats and free fatty acids the latter may be 
estimated by taking advantage of their solubility in spirit of wine, 
and the formation of a neutral soap, on shaking the spirituous solu- 
tion with caustic soda, phenolthalein being used as indicator. (See 
the section on the use of the caustic-soda solution in volumetric 
analysis.) 

The author found {Pharmaceutical Journal, March, 1863) that 
oleic acid readily combines with alkaloids and most of the metallic 
oxides or hydrates, forming oleates which are soluble in fats. In 
this way active medicines may be administered internally in con- 
junction with oils or externally in the form of ointments (Oleatum 
Hydrargyria U. S. P. ; Oleatum Veratrince, U. S. P.). Tichborne 
considers the formula of mercuric oleate to be Hg(C 18 H 33 2 ) 2 H 2 0. 

Some fats, such as "suint'" from sheep's wool, and unctuous mat- 
ter from bristles, feathers, horn, and hair, generally yield, by saponi- 
fication, etc. fatty acids, and, instead of glycerin, cholesterin. an 
alcoholoid crystalline substance (Liebrich). The "lanolin" of 
pharmacy is cholesterin fat which has absorbed a large volume of 
water. 

As regards the conversion of oily substances into emulsions 
resembling the common natural emulsion, milk, Gregory states that 
three drachms of gum acacia in fine powder are necessary to emul- 
sify one ounce of any of the volatile oils, and that a little less (about 

*Any such decomposition of water and fixation of its elements, 
whether direct as above or indirect through the intermediate agency of 
saponification, is termed hydrolysis (i'^up, hudor, water, ?.vu } luo, to decom- 
pose). The fixation of water without decomposition is termed hydra- 
tion. 



soaps. 453 

two drachms) will answer for the fixed oils and balsams. To this 
quantity of gum four drachms and a half of water must be added 
(no more and no less). Either the water or the oil may be added 
first to the gum, but it is the quickest to add the oil first and well 
triturate before adding the water. 

Soaps. 

Olive oil boiled with solution of potash yields potassium soap or 
soft soap (Sapo Mollis, B. P. ; Sapo Viridis, U. S. P., or green soap) ; 
with soda, sodium soap, or hard soap (Sapo, U. S. P.), or white cas- 
tile soap, as distinguished from the variety of hard castile or Mar- 
seilles soap, which is "mottled" by iron soap; mixed with am- 
monia, an ammonium soap (Linimentum Ammonice, U. S. P.) ; and 
with lime-water, calcium soap (Linimentum Calcis, U. S. P.), — all 
oleates, chiefly, of the respective basylous radicals. Their mode of 
formation is indicated in the foregoing equation. The alkali soaps 
are soluble in alcohol, the others insoluble. A green soap much 
used on the continent of Europe, and indeed official in Germany 
(formerly as Sapo Viridis, now as Sapo Kalinus Venalis), is made 
by adding indigo to ordinary soft soap ; the yellow color of the soap 
yielding with the indigo a greenish compound. The official charac- 
ters of hard soap are — " grayish-white, dry, inodorous ; horny and 
pulverizable when kept in dry warm air ; easily moulded when 
heated ; soluble in rectified spirit, leaving not more than 3 per cent, 
of insoluble matter, of which at least two-thirds are soluble in 
water. A 4 per cent, alcoholic solution should not gelatinize on 
cooling (abs. of animal fats) ; not imparting an oily stain to paper : 
incinerated, it yields an ash which does not deliquesce. And of 
soft soap : "yellowish-green, inodorous, of a gelatinous consistence 5 
soluble in rectified spirit ; not imparting an oily stain to paper : 
when dried yields nothing to benzol : incinerated, it yields an ash 
which is very deliquescent." Curd soap (Sapo Animalis, B. P.) is 
"a soap made with soda and a purified animal fat, consisting princi- 
pally of stearin." It will, of course, chiefly contain stearate of 
sodium. In pharmacy it is often advantageously employed instead 
of the "hard soap." 

The hard soap met with in trade is made from all varieties of oil, 
the commoner kinds being simply the product of the evaporated 
mixture of oil and alkali, while the better sorts have been separated 
from alkaline impurities and the glycerin by the addition of com- 
mon salt to the liquors, which causes the precipitation of the pure 
soap as a curd. Potash soap is not so readily precipitable by salt. 
Saponification on the small scale is much facilitated by first well 
mixing the oil with 5 per cent, of sulphuric acid, and Jetting this 
mixture stand for twenty-four hours. The dark product is then 
readily soluble when boiled with soda, and the clear fluid yields a 
crust of white soap on cooling. If required quite free from alkali, 
the resulting soap is boiled with water until dissolved, salt added, 
and the whole cooled. A cake of pure soap results. 

Yellow soap is a common, cheap soap, containing a good deal of 



454 ORGANIC CHEMISTRY. 

resin soap, resin consisting chiefly of acids — pinic, sylvic, pimaric, 
etc. — which readily unite with alkalies to form true soaps. 

Saponification. — This term is now extended in chemistry so as 
to include any process analogous to the foregoing, any reaction in 
which an alkali decomposes any ethereal salt or alkyl salt. 

Solid Fats. 

1. Lard (Adeps Prceparatus, U. S. P.) is the purified internal fat 
of the abdomen of the hog — the perfectly fresh omentum or flare, 
freely exposed to the air to dissipate animal odor, rubbed to break 
up the membranous vesicles, melted at about 130° F. (54.4° C), and 
filtered through paper or flannel. Lard Oil (Oleum Adipis, U. S. 
P.), which is chiefly olein, is a " fixed oil expressed from lard at a 
low temperature." Sp. gr. 0.900 to 0.920. 2. Benzoated Lard 
(Adeps Benzoatus, U. S. P.) is prepared lard heated over a water- 
bath with 2 per cent, of benzoin, which communicates an agreeable 
odor and prevents or retards rancidity. Purified lard is a mixture 
of oleine and stearin : margarine, the margarate of glyceryl, was 
formerly supposed to be a constituent of lard and other soft fats, 
but is now regarded as a mere mixture of palmatine (the chief fat 
of palm oil) and stearin. 3. Suet, the internal fat of the abdomen 
of the sheep, purified by melting and straining, forms the official 
Sevum, U. S. P. ; it is almost exclusively composed of stearin 
(C 3 H 5 3C 18 II 35 2 ). 4. Expressed oil of nutmeg {Oleum Myristicce 
Expression, B. P.), commonly but erroneously termed Oil of 
Mace, is a mixture of a little volatile oil with much yellow and 
white fat ; the latter is myristin or myristate of glyceryl 
(C 3 H 5 3C H H 2t 2 ). 5. Oil of theobroma, or Cacao-butter "(Oleum 
Theobromce, U. S. P.), chiefly stearin, but with one higher and 
some lower homologues (Heintz), is a solid product of the roasted 
and roughly crushed seeds or cocoa-nibs of the Theobroma cacao. 
They contain from one-fourth to one-half of this fat. (These also 
furnish when ground flake cocoa ; or, when ground and much 
sweetened, chocolate; or, with farina and some sugar, cocoa; or, 
with a portion of the butter extracted, " cocoatina," etc.). 6. Cocoa- 
nut oil or butter, a soft fat largely contained in the edible portion 
of the nut of Cocos nucifera, or common cocoanut of the shops, is a 
body containing glyceryl united with no less than six different univ- 
alent acidulous radicals— namely, the caproic (C 6 H n 2 ), caprylic 
(C 8 H 15 2 ). rutic (C 10 H ]9 O 2 ), lauric (C 12 H 23 2 ), myristic (C u H 27 2 ), and 
palmitic (C 16 H 3 j() 2 ) — radicals which, like some from common resin, 
when united with sodium form a soap differing from ordinary hard 
soap (oleate of sodium) by being tolerably soluble in a solution of 
chloride of sodium; hence the use of cocoanut oil and resin in mak- 
ing marine soap, a soap which, for the reason just indicated, readily 
yields a lather in sea-water. 7. Kokum Butter, Garcinia Oil, or 
Concrete Oil of Mangosteen, a whitish or yellowish-white fat ob- 
tained from the seeds of Garcinia indica or G. purpurea, is com- 
posed of stearin, myristicine, and olein. It is recognized officially 
in the Pharmacopoeia of India (Garcinios purpureas Oleum). 



FIXED OILS. 455 

Butter commonly yields 87 J per cent, of fat acids by saponification 
and decomposition of the soap by acid. Other animal fats, with which 
butter is likely to be. adulterated, yield about 95 J. Hence the per- 
centage of fat acids, and, especially, volatile acids, insoluble acids, 
and soluble acids, yielded by a suspected sample of butter indicates 
purity or the opposite. Occasionally, however, a sample of genuine 
butter may not conform to the figures ; hence they cannot be relied 
on to show extent of sophistication. 

Fixed Oils. 

Fixed and Volatile Oils are naturally distinguished by their be- 
havior when heated ; they also generally differ in chemical constitu- 
tion — a fixed oil being, apparently, a combination of a basylous with 
an acidulous radical, as already stated, while a volatile oil is more 
commonly a neutral or normal hydrocarbon or the same oxidized. 

Drying and Non-drying Oils. — Among fixed oils, most of which 
are oleate with a little palmitate and stearate of glyceryl, a few, 
such — as (1) Linseed oil {Oleum Lint, U. S. P., contained in Linum, 
U. S. P., Linseed or Flaxseed, the ground residue of which " should 
yield, when extracted with disulphide of carbon, not less than 25 
per cent, of fixed oil," is linseed meal), and (2) Cod-liver oil (Oleum 
Morrhuce, U. S. P.), and to some extent castor and croton — are known 
as drying oils, from the readiness with which they absorb oxygen 
and become hardened to a resin. Linseed commonly' contains 37 or 
38 per cent, of oil ; 25 to 27 per cent, is obtained by submitting the 
ground seeds to hydraulic pressure, 10 or 12 per - cent, remaining in 
the residual oil cake. Boiled oil is linseed oil which has been boiled 
with oxide of lead. This treatment increases the already great tend- 
ency of linseed oil to resinify, forming linoxyn, C 32 H 54 O n , on expo- 
sure to air. The drying oils appear to contain linolein, an oily body 
distinct from olein. Cod-liver oil contains a trace of iodine ; a little 
choline also and other bases, Gautier and Mourgues having recently 
isolated asellin, C 25 H 32 N 4 , and" morrhuine, C 19 H 27 N" 3 . Among the 
non-drying oils are the following : (3) Almond oil (Oleum Amygdalae 
Expressum, U. S. P.), indifferently yielded by the bitter (Amygdalae 
Amara, U. S. P.) or sweet seed (Amygdalcc JDulcis, U. S. P.) to the 
extent of 45 and 50 per cent, respectively. (3a) Cotton-seed oil ( Ole- 
um Gossypii Seminis, U. S. P.) contains olein and some palmitin. 
Sp. gr. 0.920 to 0.930. It should not be permanently colored dirty 
yellow by sulphuric acid. (4) Croton oil (Oleum Urotonis, B. P., 
and Oleum Tiglii, U. S. P.). Geuthcr states that no such acid as 
crotonic is obtainable from croton oil, but acetic, butyric, valerianic, 
and higher members of the oleic series, together with tiglic acid. 
IIC 5 II 7 2 . II. Senier states that alcohol separates croton oil into a 
vesicating portion which is soluble, and a powerful purgative por- 
tion which is insoluble. Robert says that free crotonoleic acid is 
both the vesicant and the purgative. (5) Lycopodium (U. S. P.), a 
yellow powder composed of the spores of the common Club-Moss 
{Lycopodium clacalum), contains a large proportion of a very fluid 
fixed oil; also an alkaloid (Bodeker), t , : ., i ll,,N,,0... (6) Olive oil 



456 ORGANIC CHEMISTRY. 

{Oleum Olivce, U.S. P.), already noticed (p. 461). "If 1 gm. of 
olive oil be agitated in a test-tube with 2 gm. of a cold mixture pre- 
pared from equal volumes of strong sulphuric acid and of nitric 
acid of sp. gr. 1.185, and the mixture be set aside for half an hour, 
the supernatant oily layer should not have a darker tint than yellow- 
ish ; nor should a green or red layer separate on standing if 1 gm. 
of the oil be shaken for a few seconds with 1 gm. of a cold mixture 
of sulphuric acid (sp. gr. 1.830) and nitric acid (sp. gr. 1.250), and 1 
gm. of disulphide of carbon ; and if 5 drops of the oil are let fall 
upon a thin layer of sulphuric acid in a flat-bottomed capsule, no 
brown-red or dark-brown zone should be developed within three 
minutes at the line of contact of the two liquids (abs. of appreciable 
quantities of other fixed oils of similar physical properties)." — 
U. S. P. (7) Castor oil (Oleum Ricini, U. S. P.), chiefly a ricinole- 
ate of glyceryl (C 3 H 5 3C 18 H 33 3 ) or ricinolein, a slightly oxidized olein, 
soluble, unlike most fixed oils, in alcohol and in glacial acetic acid. 
Castor-oil seeds were stated, by Tuson, to contain an alkaloid, rici- 
nine. Beck has recently confirmed Tuson, giving as the formula 
C 24 H 32 N 7 3 . It possesses no purgative property. (8) Oil of Male 
Fern, a vermifuge obtained by exhausting the rhizome (Aspidium, 
U. S. P.) with ether and removing the ether by evaporation — a dark- 
colored oil containing a little volatile oil and some resin, and offici- 
ally termed an oleoresin (Oleoresina Aspidii, U. S. P.). Its chief 
active constituent appears to' be JUicic acid, C 14 H 18 5 . (9) Fixed oil 
of Mustard, a bland, inodorous, yellow or amber oil, yielding by 
saponification and action of sulphuric acid, glycerin, oleic acid, and 
erucic acid (HC 22 H 41 2 ) (Darby). (10) Arachis oil (Oleum Arachis, 
P. I.) is found to the extent of 40 or 50 per cent, in the seeds of 
Arachis hypogcea (P. I.), the Ground-nut or Earth-nut (so called 
because the pod of the herb in the growth of its stalk downward is 
forced beneath the surface of the ground, and there ripens). It is 
chiefly olein, but contains hypogsein, palmitin, and arachin. The 
oil is largely used in India in the place of olive oil, and is becoming 
much employed in Europe, especially for soap-making. (11) Sesame 
oil, or oil of sesamum (Oleum Sesami, U. S. P.) (Gingelly, Teal, or 
Benne Oil), from the seeds of Sesamum indicum, is also largely used 
in Europe. It has most of the characters of the best olive oil. (12) 
Shark-liver oil, from Squalus carcharis (Oleum Squalae, P. I.), is 
used to some extent as a substitute for cod-liver oil in India. 



Trihydric Alcohols of the C n H 2n %(OH) 3 series. 
Pyrogallol or Pyrogallic Acid. — Trihydroxybenzene, C 6 H 3 (OH) 3 . 
( Vide Index.) 

d. Other Polyhydroxyl Derivatives of Hydrocarbons. 

Only one tetrahydric alcohol is known — namely, Erythite or Lichen 
Sugar, C 4 H 6 (OH) 4 , found in Protococcus Vulgaris, Roccella Tinctoria, 
and R. fuci formes. Quercite, the sugar of acorns, is Penthydric ; 
Mannite is hexahydric. 



MANNITE AND MANNA. 457 

Hexahydric Alcohols — Mannite, C 6 H 8 (OH) 6 . — Boil manna 
with 15 or 16 parts of alcohol, filter, and set aside ; mannite 
separates in colorless shining crystals or acicular masses to 
the extent of from 90 to 80 per cent, of the manna. It is 
closely related to the sugars, glucose becoming mannite by 
action of nascent hydrogen : 

C 6 H 12 6 + H 2 = C 6 H I4 6 

Glucose. Hydrogen. Mannite. 

Indeed, glucose itself is probably an alcohol of another radical 
(C 6 H 8 ) vi 60H. Mannite does not undergo vinous fermentation 
in contact with yeast. With nitric acid it forms an explosive 
body, nitromannite, C 6 H 8 (N0 3 ) 6 . 

Manna, U. S. P., is a concrete saccharine exudation obtained 
by making transverse incisions in the stems of cultivated trees 
of Fraxinus Ovnus. It occurs in stalactitic pieces, varying in 
length and thickness, flattened or somewhat concave on their 
inner surface, and of a pale yellowish-brown color and nearly 
white externally. This manna, which is known as flake manna, 
is crisp, brittle, porous, crystalline in structure, and readily sol- 
uble in about six parts of water. Odor faint, resembling honey ; 
taste sweet and honey-like, combined with a slight acridity and 
bitterness. It contains about 10 per cent, of moisture. Man- 
nite is also met with in celery, onions, asparagus, certain fungi 
and sea-weeds, occurs in the exudations of apple ana pear trees, 
and is produced during the viscous fermentation of sugar. 

Dulcite, isomeric with mannite, is formed by the action of nascent 
hydrogen on inverted milk-sugar. It differs from mannite by oxidiz- 
ing to mucic acid, C f .H 10 Oo, when treated with nitric acid. 



QUESTIONS AND EXERCISES. 

742. State the composition of phenol ; how is it artificially and 
commercially prepared? 

743. State the character by which carbolic acid is distinguished 
from creasote. 

744. Give the formulae and systematic names for picric acid, car- 
bolate of sodium, and resorcin. 

745. Give names for the bodies having tho formulae CLILOII.CIL 
and C 6 H 5 CH 2 OH. 

74(>. What are glycols ? how prepared ? 

747. Give formula and mention the chief properties of glycerin. 

748. What is the specific gravity of glycerin ? 

749. By what test is glycerin recognized ? 

750. Enumerate some official preparations in which glycerin is 
employed as a solvent. 

751. Give a sketch of the general chemistry of fixed oils, fats, and 



458 ORGANIC CHEMISTRY. 

752. What is the difference between hard and soft soap? 

753. Which soaps are official ? 

754. Name the source of lard, and state how "Prepared Lard" is 
obtained. 

755. Mention the chief constituent of suet. 

756. Whence is cacao-butter obtained? 

757. Why is marine soap so called? and from what fatty matter is 
it almost exclusively prepared? 

"58. What do you understand by drying and non-drying oils? 

759. In what respects does castor oil differ from other oils? 

760. How is oil of male fern {Ex. Filicis Liquidum) prepared ? 

761. Under what head do the following fall: pyrogallol (Pyrogal- 
lic acid), erythite, mannite, and dulcite? 

762. Describe the source and characters of manna. 



CARBOHYDRATES. 

The carbohydrates may be placed in three classes : — 

r nn ft /n «. f Glucose or Dextrose or Grape-Sugar. 

1 . C 6 H 12 6 , Glucoses j L ^ vulose or Inverted guga * - 

o n it ft' o i f Cane-Sugar or Sucrose. 

2. C 12 H 22 O u , Saccharoses 1 Maltose ° 

or Saccharons ] T i. " twtmi a 

I Lactose or Milk-Sugar. 

o n tt r\ a i ( Dextrin. 

3. C 6 H 10 O 5 Amyloses or g^^ 

Amyloids j Cellulose. 

Glucoses, C 6 H 12 6 . 

Dextrose or Grape- Sugar or Glucose (from yXvicvg, glucils, sweet) is 
often seen in the crystallized state in dried grapes or raisins and 
other fruits ; it is also the variety of sugar met with in diabetic 
urine. Its crystalline character is quite distinct from that of cane- 
sugar, the latter forming large four- or six-sided rhomboidal prisms, 
while grape-sugar occurs in masses of small cubes or square plates. 
Grape-sugar is also less soluble in water, but more soluble in alcohol 
than cane-sugar. 

According to Fresenius, the percentage proportion of saccharine 
matter in the dried fig is 60 to 70, grape 10 to 20, cherry 11, mul- 
berry 9, currant 6, whortleberry 6, strawberry 6, raspberry 4 {Rubus 
Idceus, U. S. P.). 

Lsevulose is lsevogyrate, while sucrose and glucose possess right- 
handed rotation ; the latter twist a ray of polarized light from left 
to right to an extent dependent on the amount of sugar present — a 
fact easy of application in estimating the amount of sugar in syrups 
or in diabetic urine. 

Inverted Sugar or Lcemdose is uncrystallizable. It is found in the 
grape, fig (Ficus, U. S. P.), cherry, and gooseberry ; both grape-sugar 
and inverted sugar in the strawberry, peach, plum, etc. Fruit-sugar 
reduces cupric salts and ammonio-nitrate of silver. 



GLUCOSES. 459 

Artificial Formation of Grape- Sugar from Cane- Sugar — 
Testa for Sugar. — Dissolve a grain or two of common cane- 
sugar in water. To a portion of this solution placed in a test- 
tube add more water, two or three drops of solution of sul- 
phate of copper, a considerable quantity of solution of potash 
or soda (enough to turn the color of the liquid from a light to 
a dark blue), and heat the mixture to the boiling-point; no 
obvious immediate change occurs. To another portion of the 
syrup add a drop of sulphuric acid and boil for ten or twenty 
minutes, then add the copper solution and alkali, and heat as 
before ; a yellowish-red precipitate of cuprous oxide (Cu 2 0) 
falls. This test is exceedingly delicate. 

The above reaction is due to the conversion of the cane-sugar 
(C 12 H 22 O n ) into inverted sugar or Icevulose, C 6 H 12 6 (so called 
because its solution causes left-handed rotation of a ray of polar- 
ized light, cane-sugar having an opposite effect), and grape-sugar, 
C 6 H 12 6 .H 2 0, by the influence of the sulphuric acid, and to the 
reducing action of the inverted sugar and grape-sugar on the cupric 
solution. The formation of a precipitate immediately, without the 
action of acid, shows the presence of the latter sugars — its forma- 
tion only after ebullition with acid indicating, in the absence of 
starch or dextrin, cane-sugar. In this reduction process the sugar 
is oxidized and broken up into several substances, but the exact 
nature of the reaction has not been ascertained. 

Dextrin also reduces the copper salt to suboxide, unless its solu- 
tion is cold and very dilute. It does not, however, so act on a solu- 
tion of Cupric acetate acidified with acetic acid, while glucose pro- 
duces with this liquid the usual red cuprous precipitate (Barfoed). 

Sugar from Starch. — Boil starch with a little water and a 
drop of sulphuric acid, as for dextrin, but continue the ebulli- 
tion for several minutes ; on testing a portion of the cooled 
liquid with iodine, and another portion with the heated alka- 
line solution of a copper salt, as described on page 547, it will 
be found that the starch has nearly all become converted into 
a sugar — dextrose. Maltose is also formed at first, but by the 
continued action of the acid is changed to dextrose. When 
made on a large scale, a warm (131° F.) mixture of starch and 
water of the consistence of cream is slowly poured into a boil- 
ing solution of one part of sulphuric acid in one hundred of 
water, the whole boiled for some time, the acid neutralized by 
chalk, the mixture filtered, the liquid evaporated to a thick 
syrup, and set aside; in a few days it crystallizes to a granular 
mass resembling honey. In this operation a small quantity of 
dextrin remains with the glucose, but if the process be con- 
ducted under pressure, conversion, according to Manbr6, is 
complete. Sugar made from the starch of rice, maize, etc. is 



460 ORGANIC CHEMISTRY. 

now largely used for table syrups, confectioneries, bee-food, 
and as a partial substitute for malt in brewing. It is known 
as patent sugar, saccharine, maltose, etc. 

In the United States the dealers term the syrups -" glucose,' ; and 
the further evaporated solid product " grape-sugar.'' The former 
contain one-third or more, of dextrose, about one-fifth of maltose, 
one or more of dextrin, and about one-sixth or one-fifth of water ; 
the latter often contain about three-fourths of dextrose, from none 
up to one third of maltose, and one-seventh or one-sixth of water. 

Galactose (from milk-sugar), Arabinose (from gum arabic), Sorbin 
(from mountain-ash berries), Eucalin (from melitose), Inosite (from 
muscles), Dambose (from a caoutchouc), and Scyllite (from many 
fish), all apparently belong to the glucoses. 

Saccharoses or Saccharons, C 12 II 12 O n . 

Cane- Sugar or Sucrose (Saccharum, U. S. P.) is a frequent con- 
stituent of vegetable juices. Thus it forms the chief portion of 
cassia-pulp (Cassice Pidpa, U. S. P.), is contained in the carrot and 
turnip, but is most plentiful in the sugar-cane ; much, however, is 
now obtained from the sugar-maple and beet-root. On evaporation 
of the juice common brown or moist sugar crystallizes out; this 
by resolution, filtration through animal charcoal, evaporation to a 
strong syrup, and crystallization in moulds, yields the compact 
crystalline conical loaves known in trade as lump sugar. From a 
slightly less strong syrup, slowly cooled, the crystals termed sugar 
candy are deposited, white or colored, according to the color of the 
syrup. The official syrup (Syrupus, U. S. P.) is an aqueous solu- 
tion containing 65 per cent, of sugar. 

The sugar in fresh fruits is mainly cane-sugar ; but by the action 
of the acid, or possibly of a ferment in the juice, it is gradually 
converted into inverted sugar, a variety differing from cane-sugar in 
being uncrystallizable, and in having an inverted or opposite influence 
on polarized light, twisting the ray from right to left (Isevogyrate, 
having lasvo-rotation — hence sometimes termed Icevulose). Ripe hips 
(Boso3 Canince Fructus, B. P.) contain 30 per cent, of such sugar, 
besides gum and acid malates and citrates. Fruit-sugar, as gath- 
ered in the form of syrup by bees, is probably a mixture of these 
two varieties. It is gradually altered to a crystalline or granular 
mass of grape-sugar, as seen in dried fruits, such as raisins (Uvo3, 
B. P.) and the prune (Prunum, U. S. P.), and in solidified honey 
(Mel, B. P., U. S. P.). This, the common form of grape-sugar, is 
dextrogyrate, and hence is sometimes termed dextrose, to distinguish 
it from laevulose. Diluted with twice its weight of water, it yields 
a liquid having the sp. gr. 1.101 to 1.15. Honey often contains 
pollen, hairs, spores, the dust and dirt from the flowers, and various 
flocculent matters which cause it to ferment and yield mannite, alco- 
hol, and acetic acid; hence for use in medicine it is directed (Mel 
Despumatum, U. S. P.) to be clarified by melting and straining 
while hot through flannel previously moistened with warm water. 



SACCHAROSES. 461 

A mixture of clarified honey 80 per cent., acetic acid 10 per cent., 
and water 10 per cent, is official under the name of Oxymel (from 
b^vc, oxus, acid, and f/iXi, meli, honey). A similar mixture of honey 
with acetic acid, containing the soluble portions of squill-bulbs 
(Scilla, U. S. P.), is known as Oxymel of Squill {Oxymel Scillce, 
B. P.). Honey or cane-sugar are the bases of the official Con- 
fections. 

Maltose, C 12 H 22 O n . — This crystallizable sugar is formed, together 
with dextrin, when diastase or dilute acids act upon starch. In the 
case of diastase it is the ultimate product, but the dilute acids may 
convert it into dextrose. It differs also from dextrose in its optical 
activity. 

Cane-sugar, maltose, and grape-sugar yield alcohol and carbonic 
acid gas by fermentation, the cane-sugar probably always passing 
into grape-sugar before the production of alcohol commences :— 

e 6 H ia O, = 2C 2 H 5 HO + 2C0 2 

Grape-sugar. Alcohol. Carbonic acid gas. 

In oread-making some of the starch is converted into dextrin, and 
this into sugar by the ferment. The above action then goes on, the 
liberation of gas producing the rising or swelling of the mixture of 
flour, water, and yeast (dough) — the temperature to which the mass 
is subjected in the oven causing escape of most of the alcohol, and 
further expansion of the bubbles of carbonic acid gas in every part 
of the now spongy loaf. The carbonic acid gas gradually evolved 
when flour is worked up for bread with a mixture of dry bicarbonate 
of sodium and tartaric acid (best preserved by previous admixture 
with dried flour and a little carbonate of magnesium) — baking-pow- 
der — exerts similar influence. The least objectionable method of 
introducing carbonic acid gas, however, is that of Dauglish, whose 
patent derated bread is made from flour by admixture with carbonic 
acid water under pressure by the aid of machinery. On removal 
from the cylinder the resulting dough expands by the natural elas- 
ticity of the imprisoned carbonic acid gas, and the bake-oven com- 
pletes the process. The crumb of bread is official in Great Britain 
{Mica Panis, B. P.). 

Action of Alkali on Sugar. — To a little solution of grape- 
sugar add solution of potash or soda or solution of carbonate 
of potassium, and warm the mixture ; the liquid is darkened 
in color from amber to brown, according to the amount of 
sugar present. A trace of picric acid greatly intensifies the 
color. 

Tests. — The copper reaction, the fermentation process, and 
the effect of alkalios form three good tests of the presence of 
grape-sugar, and, indirectly, of cane-sugar. A piece of merino 
or other woollen material, previously dipped in a solution of 
stannio chloride and dried, becomes of a brown or black color 
when dipped in a solution of glucose and heated to about 300° 
.F. by holding before a fire. 
39* 



462 ORGANIC CHEMISTRY. 

Meletizose (from the larch), Melitose (from eucalyptus), Trehalose 
(from Turkish manna), and Maltose (from starch), belong to the 
Saccharons. 

" Honey-dew'"' is a viscid saccharine matter occasionally met with 
on the leaves of the lime, maple, black alder, rose, and other trees, 
being a sweet principle exuded from aphides. Sometimes it is suf- 
ficiently abundant to dry and fall on the ground, forming a veritable 
" shower of manna," It is a mixture of cane-sugar, inverted sugar, 
and dextrin. 

Barley-sugar is made by simply heating cane-sugar till it fuses, a 
change from the crystalline to the uncrystallizable condition occur- 
ring. Treacle (Theriaca, B. P.), Molasses or Melasses (from Mel, 
honey), or Golden Syrup, chiefly results from the application of too 
much heat in evaporating the syrups of the sugar-cane ; it is a mix- 
ture of cane-sugar with uncrystallizable sugar and more or less 
coloring-matter. Liquorice-root {Glycyrrluzce, Radix, B. P.) con- 
tains a considerable quantity of uncrystallizable sugar. 

Caramel. — Carefully heat a grain or two of sugar in a test-tube 
until it blackens: the result is caramel or burnt sugar (the Sacclia- 
rum Usturn of pharmacy). It is used as a coloring agent for gra- 
vies, confectioneries, spirits, and similar materials. 

Milk-Sugar, or Lactose (C 12 H 2i 12 ) (Saccharum Laciis, U. S. P.), 
the SAveet principle of the milk of various animals, is not susceptible 
of alcoholic or vinous fermentation, but it resembles grape-sugar in 
reducing an alkaline solution of copper with precipitation of sub- 
oxide. It is readily obtained from milk by adding a few drops of 
acid, stirring, setting aside for the curds to separate, filtering, evap- 
orating the u-liey to a small bulk, filtering again if necessary, and 
allowing to cool and crystallize. It usually occurs in trade " in cyl- 
indrical masses two inches in diameter, with a cord or stick in the 
axis, or in fragments of cakes — grayish-white, crystalline on the 
surface and in its texture, translucent, hard, scentless, faintly sweet, 
gritty when chewed."' It is soluble in 6 parts of cold and 3 of 
boiling water : slightly soluble in alcohol : insoluble in ether. Pow- 
dered milk-sugar is used in pharmacy as a vehicle for potent solid 
medicines. Milk-sugar is convertible, by the action of dilute acids. 
into " galactose " and " lacto-giucose ;" these may be reunited to 
form milk-sugar. " Milk-sugar, when sprinkled upon 5 parts of 
sulphuric acid, should acquire not more than a greenish or reddish, 
but no brown or blackish-brown, color within* one hour (abs. of cane- 
sugar)." — U. S. P. 

Saccharic Acid, H 2 C 6 H 8 8 , or C 4 H 4 (OH) 4 (COOH) 2 , is the 
result of oxidizing sucrose, dextrose, starch, gum, and lignin 
by nitric acid. Alucic acid, isomeric with saccharic acid, may be 
obtained in the same way by acting on lactose, gum, and mannite. 



QUESTIONS AND EXERCISES. 

763. Into what three classes may the carbohydrates be divided 

764. How is grape-sugar obtained from cane-sugar? 



AMYLOSES. 463 

765. How are cane-sugar and grape-sugar analytically distin- 
guished ? 

766. How is dextrose obtained from starch ? 

767. Mention the chief sources of cane-sugar. 

768. Give chemical explanations of the different processes of 
bread-making. 

769. What is the difference between fruit-sugar and honey ? 

770. What is oxymel ? 

771. Describe the effect of heat on cane-sugar. 

772. How is milk-sugar obtained? In what respects does it differ 
from other sugar? 

773. Whence are mucic and saccharic acids obtained ? 



Amyloses or Amyloids, nC 6 H 10 O 5 . 

Starch («C 6 H 10 O 5 , probably C 72 H 120 O 60 ) is contained in large 
or small quantities in nearly every plant. It forms about 60- 
70 per cent, of wheat, and from 20 to 30 per cent, of potatoes. 

Processes. — Rasp or grate, or, with a knife, scrape, a portion 
of a clean raw potato, letting the pulp fall on to a piece of 
muslin placed over a small dish or test-glass, and then pour a 
slow stream of water over the pulp ; minute particles of gran- 
ules of starch pass through the muslin and sink to the bottom 
of the vessel, fibrous matter remaining on the sieve. This is 
potato-starch. Even diseased potatoes furnish good starch 
by this method. Wheat-starch (Amylum, U. S. P.) may be 
obtained by tying up some flour in a piece of calico, and 
kneading the bag in a slow stream of water flowing from a 
tap, the washings running into a deep vessel, at the bottom of 
which the white starch collects ; the sticky matter remaining 
in the bag is gluten. 

The blue starch of the shops is artificially colored with smalt or 
indigo to neutralize the yellow tint of recently washed linen : it 
should not be used for medicinal purposes. Starch dried in mass 
splits up into curious columnar masses resembling the basaltic pil- 
lars of Fingal's Cave in Staffa or those of the Giant's Causeway in 
the north of Ireland. The cause of the phenomenon, which may 
also be seen in grain tin, is not conclusively known. 

Gluten is the body which gives tenacity to dough and bread. It 
seems to be a mixture of vegetable fibrin, vegetable casein, and an 
albuminous matter termed gluten. These substances and gluten 
itself are closely allied ; each contains about 16 per cent, of nitro- 
gen. Wheaten Flour {Farina Tritici, B. P.) contains about 72 per 
cent, of starch and 11 of gluten, as well as sugar, gum. fine bran, 
water, and ash. The compactness of barley, well seen in Husked 
or Pearl Barley (Hordeum Decorticatum, B, P.), is said to be due to 
the large amount of vegetable fibrin present. Paring germination 



464 ORGANIC CHEMISTRY. 

the fibrin is destroyed ; hence, probably, the cretaceous character of 
malt. Oatmeal {Avence Farina, U. S. P.) is very rich in albumenoid 
or flesh-forming constituents, containing nearly 16 per cent.. Sago 
is granulated starch from the Sago Palm. Tapioca is granulated 
starch from the Bitter Cassava. The white translucent grains known 
as Rice are the husked seeds of Oryza sativa. Rice ( Oryza) and the 
Flour of Rice, or Ground Rice {Oryzai Farina), are official in the 
Pharmacopoeia of India. Rice is quite a staple article of food in 
tropical countries. Ground rice resembles flour of wheat in compo- 
sition, but contains from 85 to 90 per cent, of starch. 

Mucilage of Starch. — Mix two or three grains of starch with 
first a little and then more water, and heat to the boiling-point ; 
mucilage of starch {Mucilago Amyli, B. P.) results. 1 part of 
starch to 200 of water gives Gelatinized Starch, U. S. P. 

This mucilage or paste is not a true solution ; by long boiling, 
however, a portion of the starch becomes dissolved. In the latter 
case the starch probably becomes somewhat altered. 

Chemical Test. — To some of the mucilage add a little free 
iodine ; a deep blue color is produced. 

This reaction is a very delicate test of the presence of either iodine 
or starch. The starch must be in the state of mucilage ; hence in 
testing for starch the substance supposed to contain it must be first 
boiled with water. The solutions used in the reaction should also 
be cold, or nearly so, as the blue color disappears on heating, though 
it is partially restored on cooling. The iodine reagent maybe iodine- 
water or tincture of iodine. In testing for iodine, its occurrence in 
the free state must be ensured by the addition of a drop, or even 
less, of chlorine-water. Excess of chlorine must be avoided or 
chloride of iodine will be formed, which does not color starch. 

The so-called iodide of starch scarcely merits the name of a chem- 
ical compound, the state of union of its constituents being so feeble 
as to be decomposed at 100° F. Substances that attack free iodine 
remove that element from iodide of starch. The alkalies, hydro- 
sulphuric acid, sulphurous acid, and other reducing agents destroy 
the blue color. With nitric acid starch jdelds an explosive com- 
pound {Xyloidin) C 12 H 16 (NO 2 ) 4 O 10 . 

Composition of Starch- Granules. — Starch-granules consist mainly 
of granulose, soluble in cold water and giving an indigo color with 
iodine, and starch cellulose, insoluble in water and giving with iodine 
a dirty-yellow color, with, possibly, other carbohydrates. The starch 
cellulose forms an external coating upon the granule, and also exists 
mixed with the granulose inside the granule. If this coating be 
broken by mechanical means, the continued application of cold water 
will remove all the granulose, leaving the cellulose insoluble. By 
the action of diastase, ptyalin, and other ferments, and by other 
means, the granulose may be converted into sugar and dextrin, leav- 
ing the starch cellulose unacted upon. 



465 



-9Mfh of an inch. , 



STARCHES 

(Magnified 250 diameters). 



Tins. 4'i to 49. 




4G6 ORGANIC CHEMISTRY. 

Microscopical Examination of Starches. 

All kinds of starch afford the blue color with iodine, showing 
their chemical similarity. Physically, however, the granules of dif- 
ferent starches differ from each other ; hence a careful microscopical 
examination of any starch, or of any powder or vegetable tissue 
containing starch, enables the observer to state, with a high degree 
of probability, the source of the starch — either at once if he has 
much experience, or after comparing the granules in question with 
authentic specimens. A glance at the accompanying eight engrav- 
ings* (Figs. 42 to 49) of common starches will show to what extent 
different starch-granules naturally differ in size, shape, general 
appearance, distinctness and character of the rugae, and position of 
the more or less central point or hilum. While from different 
starches individual granules may be picked out which much resem- 
ble each other, the appearance of each starch as a whole is fairly 
characteristic ; that is to say, each group of granules differs in one, 
two, or several characters from similar groups of granules of other 
starches. 

A quarter-inch object-glass will commonly suffice for the micro- 
scopical observation of starch. A very little of the starch is mixed 
on a glass slide with a drop of water, a piece of thin covering-glass 
placed on the drop and gently pressed, so as to provide a very thin 
layer for observation. Instead of water, diluted spirit of wine, 
diluted glycerin, turpentine or other essential oil, Canada balsam, 
and other fluids may be used in cases where the markings or other 
appearances are not well defined. The illumination also of the 
granules may be varied, the light being reflected or transmitted, 
concentrated or diffused, white or colored, polarized or plain. Polar- 
ized light is especially valuable in developing differences and in 
intensifying the effects of obscure markings.' By polarized light the 
granules of potato-starch appear as if traversed by a black cross ; 
wheat starch-granules and many others .also peculiarly and charac- 
teristically influence polarized light. Distinctive characters will 
sometimes present themselves only when the granules are made to 
roll over in the fluid in which they have been temporarily mounted 
or when the slide is gently warmed. Starches which have already 
been subjected to the influence of heat, partly, as in sago or tapioca, 
or almost entirely, as in bread, will of course differ in appearance 
from granules of the same starch before being dried, cooked, or ter- 
rified. The characters of a starch will also somewhat vary accord- 
ing to the age and condition of the plant yielding it. 

The description of the microscopical characters of the official 
varieties of starch is as follows: 1. Wheat starch: A mixture of 
large and small granules, which are lenticular in form, and marked 
with faint concentric striae surrounding a nearly central hilum. 2. 
Maize starch : Granules more uniform in size, frequently polygonal, 

* By permission of Messrs. Longmans & Co. these engravings have 
been copied, with very few modifications, from the plates in two of the 
three volumes of the original edition of Pereira's Materia Medica. 



VARIETIES OF STARCH. 467 

somewhat smaller than the large granules of wheat starch, and hav- 
ing a very distinct hilum, but without evident concentric striae. 3. 
Rice starch : Granules extremely minute, nearly uniform in size, 
polygonal, hilum small and without striae. 

(For plates and descriptions of the characters of other starches 
occurring in plants used for medicinal purposes, the reader is referred 
to works on Materia Medica, and to the indexes of Journals of 
Pharmacy, as well as to general works and magazines on micros- 
copy. For engravings of starch-granules in situ, vide Berg's 
Anatomischer Atlas, published by Gaertner, Berlin.) 

The student may place fair confidence in the accompanying litho- 
graphs, and in most of the published engravings of starch-granules ; 
but in microscopical analyses of importance the worker should, if 
possible, himself obtain actual specimens of starches for comparison 
from the respective seeds, fruits, and other tissues. 

Inulin (C 6 H 10 O 5 ) is a white powder apparently occupying the place 
of starch in the roots of many plants, especially those of the natural 
order Compositce. 20 to 45 per cent, has been obtained from ele- 
campane (Inula helenium). It is also contained in the dahlia, col- 
chicum, arnica, dandelion, chicory, artichoke, etc. It is soluble in 
boiling water, nearly all being redeposited on cooling. Iodine turns 
it yellow. Long ebullition converts it into a kind of gum. Like 
starch, inulin is convertible "into sugar, but by its own special fer- 
ment, the existence of which, in the Jerusalem artichoke, has been 
demonstrated by Professor J. R. Green. It differs from diastase in 
being without the power of converting starch into sugar. 

LicJienin (C 6 H 10 O 5 ) is a white, starch-like powder largely contained 
in many lichens — Iceland "moss," Cetraria islandica, and many 
others. -It is soluble in boiling water, and the fluid gelatinizes on 
cooling. It may be precipitated from its aqueous solution by alco- 
hol. With iodine it gives a reddish-blue color. 

Glycogen, or animal starch, is the name given to the solid matter 
stored in the liver, and resulting from the dehydration of the 
digested hydrated food which has been carried to the liver by the 
portal vein. 

Dextrin. — Mix a grain or two of starch with about half a 
test-tubeful of cold water and a drop or two of sulphuric acid, 
and boil the mixture for a few minutes; no mucilage is formed, 
and the liquid, if sufficiently boiled, yields no blue color with 
iodine ; the starch has become converted into dextrin and some 
sugar. Dextrin is also produced if starch is maintained at a 
temperature of about 320° F. for a short time. Dextrin is 
now largely manufactured in the latter way, and a paste of it 
is used by calico-printers as a vehicle for colors ; it is termed 
British gum. The change may also be effected by diastase, a 
peculiar ferment existing in malt. Mix two equal quantities of 
starch with equal amounts of water, adding to one a little 
ground malt ; then heat both slowly to the boiling-point : the 
mixture without malt thickens to a paste or pudding ; that 



468 ORGANIC CHEMISTRY. 

with malt remains thin, its starch having become converted 
into dextrin and a sugar termed maltose. 

Diastase is probably a mixture — but possibly an oxidation prod- 
uct — of the coagulable albuminoids. It is so named from didoraaig 
(diastasis), separation, in allusion to the separation, or rather altera- 
tion, it effects among the constituent atoms of the molecule of starch. 
This function is shared by the saliva, pancreatic juice, bile, and 
the intestinal and other juices. The function is completely destroyed 
when the albuminoids are coagulated by a temperature of from 176° 
to 178° F. 

The Action of Diastase upon Starch. — Diastase has scarcely any 
action upon unbroken starch-granules. The granules must be rup- 
tured by gelatinization with heat and moisture or in some other 
way. When a solution containing diastase, such as a cold-water 
infusion of malt, is allowed to act upon gelatinous starch or starch 
paste at 140° to 160° F., liquefaction occurs. It is possible to ope- 
rate so that when liquefaction has taken place the solution shall give 
no reaction for sugar or dextrin. If this solution be concentrated 
and allowed to cool, a glistening white precipitate of soluble starch 
falls. Soluble starch is probably the result of the partial decompo- 
sition of the more complex molecule of granulose or gelatinous 
starch. The next step in the action of diastase upon gelatinous 
starch is the breaking down of the soluble starch-molecule into dex- 
trin and a sugar called maltose. At least ten dextrins are succes- 
sively produced, each simpler than the one preceding it, the propor- 
tion of maltose being correspondingly increased. The dextrins first 
produced give a red or brown color with iodine, while those last pro- 
duced, and having a simpler molecule, give no color with iodine. 
The final reaction may be expressed thus : — 

10(C 12 H 20 O 10 ) + 8H 2 = 8(C 12 H 22 O n ) + 2(C 12 H 20 O 10 ) 

Soluble starch. Maltose. Dextrin. 

The dextrins are distinguished by their rotary power, their reducing 
action on cupric salts, and in other ways. 

Starch heated with glycerin is converted into the soluble variety. 
The latter may be precipitated from an aqueous solution by strong 
alcohol. A strong solution in water gradually gelatinizes, owing 
to reconversion into insoluble starch (Zulkowsky). 

The Action of Dilute Acids upon Starch. — Dilute acids act upon 
gelatinous starch in the same way as diastase, except that the final 
product is glucose. 

Malt (the word malt is said to be derived from the Welsh mall, 
soft or "rotten") is simply barley which has been softened by 
steeping in water, allowed to germinate slightly, and further change 
then arrested by the application of heat in a kiln. During germina- 
tion the gluten breaks up and yields a glutinous substance termed 
vegetable gelatin, diastase, and other matters. To the vegetable 
gelatin is clue much of the "body" of well-malted and slightly- 
hopped beer ; it is precipitated by tannic acid ; hence the thinness 
of ale (pale or bitter) brewed with a large proportion of hop or other 
materials containing tannic acid. A portion of the diastase reacting 



gum. 469 

on the starch of the barley converts it into dextrin, and, indeed, car- 
ries conversion to the further stage of grape-sugar, as will be 
explained immediately. The temperature to which the malt is 
heated is made to vary, so that the sugar of the malt may or may 
not be partially altered to a dark-brown coloring material ; if the 
temperature is high, the malt is said to be high-dried, and is used in 
porter-brewing ; if low, the product is of lighter color, and is used 
for ale. The diastase remaining in malt is still capable of convert- 
ing a large quantity of starch into dextrin and sugar (maltose) ; 
hence the makers or distillers of the various spirits operate on a 
mixture of malted and unmalted grain in preparing liquors for 
fermentation. 

Extract of malt is an evaporated infusion of malt. Taken with 
food, its diastase aids in the conversion of starch into a variety of 
sugar termed maltose and dextrin, and, pro tanto, assists enfeebled 
digestive powers. 

3C 6 H 10 O 5 + H 2 = C 12 H 22 O u + C 6 H 10 O 5 

Starch. Maltose. Dextrin. 

As diastase begins to lose this power at a temperature above 150° F., 
that degree should not be exceeded in evaporating the infusion ; 
indeed, if the dissolved albuminoid matters are to be retained, the 
evaporation should be conducted at 120° F. 

The following method serves for the estimation of the dias- 
tastic power of malt extract : 1.5 gram of the extract is dis- 
solved in 15 c.c. of water and mixed with a mucilage of .1 gram 
of starch in 100 c.c. of water. The mixture is raised to 140° F. 
in temperature, and tested from time to time by adding two 
drops of iodine solution to 5 c.c. of it, and comparing with 5 c.c. 
of a similar mixture to which no starch has been added. No 
difference of tint between the two solutions indicates comple- 
tion of the reaction. A very good malt extract will accom- 
plish this within half an hour, but many commercial extracts 
will not do so until nearly three hours have elapsed. 

Gum is a frequent constituent of vegetable juices existing in large 
quantity in several species of Acacia. The nature of gums is very 
little known, though most probably they all belong to the carbohy- 
drates. According to Fremy, gum is a calcium salt, sometimes 
partially a potassium salt, of the gummic or arable radical, though 
consisting mostly of arabin or arabic acid alone. The formula of 
gummic acid is said to be H 2 C ]2 TI 18 O 10 ,H 2 O, but from the researches 
of O'Sullivan it would seem to be far more complex, yet a multiple 
of the empirical formula, O f) lT 10 O 5 . Gum differs from dextrin in 
yielding mucic acid when oxidized by nitric acid. Cerasin or cherry- 
tree gum is a metagummate of calcium, an insoluble modification of 
acacia gum. Bassorin, traganth in, or adraganthin (C 12 H 20 O 10 ) is a 
form of gum which is insoluble in water, but absorbs large quanti- 
ties of that liquid and forms a gelatinoid mass : it occurs largely in 
tragacanth, combined, like arabin, with calcium. l\ctin, or Yege- 
40 



470 ORGANIC CHEMISTRY. 

table Jelly (C 32 H 40 O 28 ,4H 2 O), is the body -which gives to expressed 
vegetable juices the property of gelatinizing : it forms the chief 
portion of Irish or Carrageen " Moss'' (Chondrus crispus). Ceylon 
u Moss" {Gracillaria lichenoides and G. confervoides, P. I.) contains 
from one-third to three-fourths of vegetable jelly. 

The mucilage of marshmallow-root (Althea officinalis) and of lin- 
seed or common flaxseed (Linum usitatissimum) is a gum-like sub- 
stance containing much mineral matter. It is the basis of the infu- 
sions termed mallow tea and linseed tea. Somewhat similar mucilage 
occurs in infusion of bael ; it is also largely yielded by the seeds 
of the quince (Cydnnium, U. S. P.), as well as by the bark of the 
Red or Slippery Elm (JJlmi Fulvo?) (Ulmus, U. S. P.). Salep, the 
powdered dried tubers of many species of Orchis, contains a large 
quantity of such matter. Squill also. The Indian Okra (Hibisci 
Capsuloe, P. I., from Hibiscus esculentus) and lspaghul or Spogel 
seeds (Ispaghulce semina, P. I., from Plantago ispaghula) also appear 
to contain a considerable quantity. In Sassafras-pith (Sassafras 
Medulla, U. S. P.) starch and much mucilage occur. 

Cellulin or cellulose, the woody fibre of plants, familiar, in the 
nearly pure state, under the forms of " cotton-wool'' (Gossypium, 
U. S. P., hairs of the seed of various species of Gossypium), paper, 
linen, and pith, is another substance isomeric, probably polymeric, 
with starch. Lignin is a closely-allied body, lining the interior of 
woody cells and vessels. By the action of nitric acid of various 
strengths on cellulin, peroxide of nitrogen (N0 2 ) is substituted for 
one, two, or three atoms of hydrogen — mono-, di-, or trinitrocellulin 
being formed : — 

C 6 H 10 O 5 + HNO, = C 6 1 j^ | 5 + H 2 

Cellulin. Nitric acid. Mononitrocellulin. Water. 

C 6 H 10 O 3 + 2HN0 3 = C 6 { J^}0 5 + 2H 2 

Cellulin. Nitric acid. Dinitrocellulin. Water. 

C 6 H 10 O 5 + 3HN0 3 = C 6 { 3 ^Jo 5 + 3H 2 

Cellulin. Nitric acid. Trinitrocellullin. Water. 

Trinitrocellulin is highly explosive gun-cotton ; dinitrocellulin is 
not sufficiently explosive for use instead of gunpowder ; mononitro- 
cellulin is scarcely at all explosive. The heat of a water-bath may 
explode trinitrocellulin, but not dinitrocellulin, if pure. The three 
movable atoms of hydrogen in cellulin may be displaced by bodies 
other than peroxide of nitrogen. 

Dinitrocellulin (Pyroxylinum, U. S. P.)- — Mix 6 parts of 
sulphuric acid and 5 of nitric in an earthenware mortar. 
When cooled to about 32° C. (90° F.), immerse i part of 
cotton-wool in the mixture, and stir it with a glass rod so 
that it is thoroughly and uniformly wetted by the acids. 
Macerate for about ten hours, or until a sample washed with 
water and then with alcohol is soluble in a mixture of 1 vol. 



ISOMERISM — ALLOTROPY — POLYMORPHISM. 471 

of alcohol and 3 of stronger ether. Transfer the cotton to a 
vessel containing a considerable volume of water, stir it rap- 
idly and well with a glass rod, decant the liquid, pour more 
water upon the mass, agitate again, and repeat the affusion, 
agitation, and decantation until the washing ceases to give a 
precipitate with chloride of barium or to taste acid. Drain the 
product on filtering-paper, and dry on a water-bath. 

Pyroxylin may also be made by soaking 7 parts of white filter- 
ing-paper, which has been washed in hydrochloric acid and dried, 
in a mixture of 140 parts of sulphuric acid (sp. gr. 1.82) and 70 of 
nitric acid (1.37) for three hours, and well washing the product 
(Guichard). 

Mononitrocellulin and trinitrocellidin are insoluble in a mixture 
of alcohol and ether ; dinitrocellulin or pyroxylin is soluble, the 
solution forming ordinary collodion {Collodium, U. S. P.). The 
official proportions are 4 parts of pyroxylin dissolved in a mixture 
of 70 of stronger ether and 26 of alcohol. After digesting for a 
few days the liquid is decanted from any insoluble matter and pre- 
served in a well-corked bottle. It is a colorless, highly inflammable 
liquid, with ethereal odor, which dries rapidly upon exposure to the 
air, and leaves a thin, transparent film, insoluble in water or recti- 
fied spirit. Flexible collodion {Collodium Flexile, U. S. P.) is a 
mixture "of collodion (92 parts), Canada balsam (5 parts), and cas- 
tor-oil (3 parts). Blistering -Collodion {Collodium Vesicans,1&. P.) 
is a solution of pyroxylin in acetic ether containing the active blis- 
tering principle of cantharides. A Styptic Collodion {Collodium 
Stypticum, U. S. P.) is also official. 

Tunicin, or animal cellulose, is extracted from ascidians and 
cynthians. 

Isomerism. — Allotropy. — Polymorphism. 

The composition of dextrin is represented by the same formula as 
that of starch — namely C 6 H 10 O 5 — for it has the same percentage com- 
position as starch. Inulin (p. 466) and cellulose (p. 468) have also 
a similar formula. There are many other bodies similar in centesi- 
mal composition, but dissimilar in properties ; such substances are 
termed isomeric (from laog, isos, equal, and uepog, meros, part) ; and 
their condition is spoken of as one of isomerism. There is some- 
times good reason for doubling or otherwise multiplying the formula 
of one of two isomers, isomerides, or isomeric bodies. "Thus a mole- 
cule of ethylene (defiant gas), the chief illuminating constituent of 
coal gas, is represented by the formula C 2 H 4 , while a molecule of 
amylene, an anaesthetic liquid hydrocarbon, obtained from amylic 
alcohol, though having the same percentage composition as defiant 
gas, is represented by the formula C 5 II 10 ; for amylene. when gas- 
eous, is about twice and a half as heavy as ethylene, and must con- 
tain, therefore, in each molecule, twice and a half as many atoms, 
for (Avogadro) these equal volumes must contain equal numbers oi' 
molecules 5 its formula is consequently constructed to represent those 
proportions. (Read again pages 36 to 56.) This variety ol' isomer- 



472 ORGANIC CHEMISTRY. 

ism is termed pohjmerism (from Tro/.vg, polus, many or much, and 
liepog, part). Metastannic acid (vide p. 240) is a polymeric variety, 
or polymeride, of stannic acid. An illustration of a second variety 
of isomerism is seen in the case of cyanate of ammonium and urea, 
bodies already alluded to in connection with cyanic acid. These and 
several other pairs of chemical substances have dissimilar properties, 
yet are similar not only in elemental*} 7 composition and in the cen- 
tesimal proportion of the elements, but also in the fact that each 
molecule possesses the same number of atoms. But the reactions 
of these bodies indicate the probable nature of their construction; 
and this is shown in their formulae by the disposition of the sym- 
bols. Thus cyanate of ammonium is represented by the formula 
NH 4 CNO, urea by CO(XH 2 ) 2 . Such bodies are termed metameric 
(from uera, meta, a preposition denoting change, and yepog), and 
their condition spoken of as one of metamerism. Acetate of ethyl 
(p. 404) is metameric with butyric acid (p. 493), for they have the 
same percentage composition and their vapors have the same specific 
gravity, and each therefore might be represented by the formula 
C 4 H 8 2 ; but their properties warrant us in assuming that their 
atoms occupy different positions in the two molecules — justify us 
in giving CH 3 CO.OC 2 H 5 as a picture of a molecule of acetate of 
ethyl, and C 3 H,COOII as a picture of a molecule of butyric acid. 
Acetate of methyl (CH 3 COO.CH 3 ). propionic acid (C 2 H 5 COOH),* 
and formate of ethyl (H.CO.OC 2 H 3 ) are isomers of the metameric 
variety, or metamerides ; also quinine and quinidine, cinchonine 
and cinchonidine, and many of the volatile oils, etc. The isomer- 
ism of starch and dextrin may be of a polymeric or of a metameric 
character; but Ave do not yet know which, and must therefore at 
present give them identical formulae, though it is most probable that 
many of the carbohydrates are multiples of the mere empirical 
formulae, since dextrin (C 6 H 10 O 5 ).r by hydration produces maltose, 
C ]2 H 2 .,O n . which Avould point to the formula of dextrin as being at 
least (C 6 H 10 O 5 ) 2 . Substances similar in composition and constitu- 
tion, yet differing in properties, are termed allotropic (a/v.og, alios, 
another ; rp6~oc, tropos. condition). Thus ordinary phosphorus, 
kept at a temperature of about 450° F. in an atmosphere from 
which air is excluded, becomes red. opaque, insoluble in liquids 
in which ordinary phosphorus is soluble, oxidizes extremely slowly, 
and only ignites when heated to near 500° F. (red or amorphous 
phosphorus). A black allotropic variety of phosphorus is known. 
There are also three allotropes of carbon which are respectively 
crystalline, graphitic, and amorphous. Sulphur may be obtained 
in the viscous as well as in the hard, brittle condition. Another 
illustration of allotropy is seen in the varieties of tartaric acid, 
which have different optical properties, but otherwise are identical ; 
they are in neither of the above-mentioned states of isomerism, but 
are allotropic modifications of the same substance. Occasionally 
one and the same substance crystallizes in two distinct forms ; its 
state is then described as one of polymorphism (~o/.vc, jyolus, many; 

* For explanation of formulae, see chapter on Aldehydes and Acids. 



ALDEHYDES AND ACIDS. 473 

finpor),, morphe, form). Sulphur is polymorphous. It crystallizes 
by slow cooling in (1) prismatic crystals of sp. gr. 1.98, while in 
nature it occurs in (2) octahedra of sp. gr. 2.07. Melted and poured 
into water, sulphur takes up (3) the form of caoutchouc of sp. gr. 1.96. 
These differences warrant the statement that sulphur occurs in three 
distinct allotropic conditions. Possibly, such conditions result from 
the association of different numbers of atoms in the molecule of the 
element; that is, allotropic bodies may simply be physically polymeric, 
or in some other way be mere physical isomerides. 



QUESTIONS AND EXERCISES. 

774. How is wheat-starch or potato-starch isolated ? 

775. Define gluten and glutin. 

776. Enumerate the proximate principles of wheaten flour. 

777. Is starch soluble in water? 

778. Which is the best chemical test for starch ? 

779. Distinguish physically between the varieties of starch. 

780. Into what compound is starch converted by heat? 

781. What occurs when a mixture of starch and water is allowed 
to flow into hot diluted sulphuric acid ? 

782. If two equal amounts of starch with water be heated, one 
containing a small quantity of ground malt, what effects ensue? 

783. Write a short article on the chemistry of malting. 

784. What is the nature of gum arabic? and how is it distin- 
guished from "British gum"? 

785. Mention the properties of the products of the action of nitric 
acid of various strengths on cellulin. 

786. Plow is pyroxylin prepared ? 

787. Explain isomerism, giving several illustrations. 

788. Give examples of polymeric bodies. 

789. State the formula of a body metameric with urea. 

790. Define allotropy and polymorphism, giving illustrations. 



ALDEHYDES AND ACIDS. 

General Formation. — The aldehydes and acids may be artificially 
formed by oxidation of the primary alcohols, glycols, etc. Mon- 
hydric alcohols, having only one hydroxyl (OH) group, form mono- 
basic acids, dihydric alcohols (glycols), having two hydroxyl groups, 
yield monobasic and dibasic acids ; and so on. Thus : — 

CII 3 CII 2 OIIl ., d f CH 3 COH 1 d fCII 3 COOH 

Ethyl alcohol. J J ° \ Acetic aldehyde. J \ Acetic acid. 



f yields CII 3 OII 
CH 2 OH 1 i on 

I I J Glycollic aldehyde. 

S5'? H I I and COH 



Glycol or 
Ethylene glycol. also 

COH 

I Oxalic aldehy 



r oii,on 

and -J ( I 001T 

L Glycollic acid. 

COOH 

a,,d coon 

L Oxalic acid. 



474 ORGANIC CHEMISTRY. 

It will be seen that the groups COH and COOH denote respectively 
an aldehyde and an acid, the H in the COOH group being replace- 
able by a metal, such as CH 3 CO.OXa (acetate of sodium). 

Acids may also be obtained by acting on the nitrites or cyanides 
of the hydrocarbon radicals with hydrochloric acid and water. 
Thus : — ■ 

CH 4 + Cl 2 = CH 3 C1 + HC1 

Methane. Chlorine. Monochloro- Hydrochloric 

methane. acid. 

CH 3 C1 -f KCN = CH 3 CN + KC1 

Monochloro- Cyanide of Cyanide of methyl Chloride of 

methane. potassium. or acetonitrile. potassium. 

CH,CN + 2H 2 + HC1 = CH,COOH -f NH 4 C1 

Acetonitrile. Water. Hydrochloric Acetic acid. Ammonium 

acid. chloride. 

Many aldehydes and acids occur in nature ; for example, oil of 
meadowsweet (salicylic aldehyde), oil of bitter almonds (benzoic 
aldehyde), citric acid in lemons. 

General Reactions. — Aldehydes all form crystalline compounds 
with acid sulphite of potassium ; by oxidation they yield an acid, 
and by the action of nascent hydrogen they yield an alcohol ; while 
acids, by nascent hydrogen, yield an aldehyde, and then an alcohol. 
With oxides, hydrates, carbonates, and sometimes with metals, acids 
form metallic derivatives. With the alcohols, acids yield alkyl * or 
ethereal salts, as, for instance, acetic ether. By the action of the 
chloride, iodide, or bromide of phosphorus their hydroxyl group 
is replaced by chlorine, iodine, or bromine : — 

3CH 3 COOH + PC1 3 = 3CH 3 COCl + P0 3 H 3 

Acetic Phosphorus Chloride Phosphorous 

acid. trichloride. of acetyl. acid. 

Like inorganic acids they form anhydrides by the elimination of 
water : — ntr nn 1 

2CIT 3 COOII — H 2 = cRCo} 

Acetic acid. Water. Acetic anhydride. 

The important aldehydes and acids will now be mentioned. 



The Acetic Series. 
Acids of the Acetic Series, C n H 2n+1 CO.OH (Monobasic).— Formed 
by the two general methods given — namely, from primary alcohols 
of the ethylic series and from cyanides of the paraffin hydrocarbon 

Formic acid, H.COOH. Formic aldehyde, H.COH.— See p. 404. 

* Alkyl Salts. — Alkyl, from the Arabic article al, the, as in alkali, alco- 
hol, etc., and the termination common 1o the names of such radicals as 
ethyl, amyl, and phenyl. In Germany the word ester, a mere variation 
of the word ether, is similarly employed. In the scientific chemistry of 
both countries it is thus sought to restrict the name ethers to the oxides 
of radicals, as common ether (C 2 Fr 5 ) 2 0, {Ether, B. P.). 



ALDEHYDE. 475 

Acetic Acid, CH 3 COOH (Methylformic acid).— Obtained by the 
oxidation of alcohol. See p. 294. 

Aldehyde, or Acetic Aldehyde, C 2 H 4 or CH 3 COH. 

Preparation. — Place together, in a capacious test-tube or 
flask, about four parts of spirit of wine, six of black oxide of 
manganese, six of sulphuric acid, and four of water, and gently 
warm the mixture ; aldehyde (arfcohol t/e/^rogenatus), a 
highly volatile liquid, is immediately formed and its vapor 
evolved, recognized by its peculiar, somewhat fragrant odor. 
Adapt a cork and rather long bent tube to the test-tube, and 
let some of the aldehyde slowly distil over into another test- 
tube, the condensing-tube being kept as cool as possible. Set 
the distillate aside for a day or two ; the aldehyde will have 
nearly all disappeared and acetic acid be found in the tube. 
Test the exposed liquid by litmus-paper ; it will be found to 
have an acid reaction : make it slightly alkaline by a drop or 
two of solution of carbonate of sodium, then boil to remove any 
alcohol and aldehyde present, add sulphuric acid, and notice the 
characteristic odor of the acetic acid evolved. 

These experiments will enable the process of acetification described 
in connection with acetic acid, to be more fully understood. Pure 
diluted alcohol is not oxidized by exposure to air, but in presence of 
fermentive matter or vegetable matter undergoing decay or change 
it is oxidized first to aldehyde and then to acetic acid. 

In the" above process the black oxide of manganese and sulphuric 
acid furnish nascent oxygen : — 

Mn0 2 + H 2 S0 4 = MnS0 4 + + H 2 

Black oxide Sulphuric Sulphate of Oxygen Water, 

of manganese. acid. manganese. (atom). 

The nascent oxygen then acts on the alcohol, just as the oxygen of 
#ie air acts on the alcohol in fermented infusion of malt, beer, or 
wine, giving aldehyde : — 

CH 3 CH 2 OI-I + = CII.COH 4- n,o 

Alcohol. Oxygen Aldehyde. Water. 

(atom). 

The aldehyde rapidly, even when pure (more rapidly when impure), 
absorbs oxygen and yields acetic acid : — • 

2CII3COII + 2 = 2CTI.COOII 

Aldehyde. Oxygen. Acetic acid. 

Tests. — Aldehyde heated with solution of potash gives a 
brownish-yellow resinous mass of peculiar odor. Its aqueous 
solution reduces salts of silver, giving a mirror-like coating to 
the sides of a test-tube. When acted on by phenol dissolved 
in sulphuric acid it gives a red color. Aldehyde on keeping 
yields polymerides, metaldehyde, and paraldehyde. 



476 ORGANIC CHEMISTRY. 



CHLORAL. 

Chloral or Trichhr aldehyde. CCl 3 COH. is a chlorine substitution- 
derivative of aldehyde, though it cannot directly be obtained by act- 
ing on aldehyde by chlorine, because condensation-products are 
formed. 

Process. — Pass a rapid stream of dry chlorine into pure abso- 
lute alcohol so long as absorption occurs. During the first hour 
or two the alcohol must be kept cool ; afterward gradually 
warm till ultimately the boiling-point is reached. The prepa- 
ration of a considerable quantity occupies several days. The 
crude product is mixed with three times its volume of sulphuric 
acid and distilled, again mixed with a similar quantity of sul- 
phuric acid, and again distilled, and finally rectified from quick- 
lime. 

The formation of chloral would at first sisht seem to be due to the 
production from the alcohol (CH 3 CH,OH) of aldehyde (CII 3 COH), 
through the removal of hydrogen by the chlorine, and the substitu- 
tion of chlorine for hydrogen in the aldehyde (CH 3 COH). with forma- 
tion of chlor-cddehyde or chloral (CCl 3 COH). But the reactions are 
far more complicated, being as follows : — 

Aldehyde and hydrochloric are first formed : — 

CH 3 CH,OH - Cl 2 = CH3COH + 2HC1 

Alcohol. Chlorine. Aldehyde. Hydrochloric 

acid. 

The nascent aldehyde unites with alcohol, forming acetal : — 
CH3COH + 2C 2 H 5 OH = CH 3 .CH.(OC 2 H 5 ), - H,0 

Aldehyde. Alcohol. Acetal. Water. 

Acetal * by further chlorination yields trichloracetal : — 

CH 3 .CH(OC 2 H 5 ) 2 + Cl fi = CCLCH.(OC,H 5 ) 2 - 3HC1 

Acetal. " Chlorine. Trichloracetal. Hydrochloric 

acid. 

Trichloracetal when acted on by hydrochloric acid yields ethyl 
chloride and chloral alcoholate. 

CC1 3 CH<^! 2 & + HC1 = CC1 3 CH<°^ H > - C 2 H 5 C1 

Trichloraeetah Chloral Ethyl 

alcoholate. chloride. 

From the alcoholate. chloral is liberated by treatment with sulphuric 

acid : — 

CCl ? ,CH.(OC 2 H 5 )OH - H,SO, = CC1 3 C0H - C,H 5 HS0 4 + OH 2 

Chloral alcoholate. Sulphuric Chloral. Ethyl-hydrogen Water, 

acid. sulphate. 

*Methylal, CH, (OCH s ) a the lowest term of the series, is occasionally 
used as a soporific. 



CHLORAL. 477 

Properties. — It is a colorless liquid, of oily consistence. Sp. gr. 
1.502. Boiling-point, 201.2° F. Its vapor has a penetrating smell, 
and is somewhat irritating to the eyes. Mixed with water, heat is 
disengaged and solid white, crystallizable, hydrous chloral {Chloral, 
U. S. P.), CC1 3 CH(0H) 2 , or, what is more generally though irregu- 
larly termed chloral hydrate, or Hydrate of Chloral {Chloral Hydras, 
B. P.), results. Hydrous chloral is a true glycol, the water not 
being simply water of crystallization, but of combination, the sys- 
tematic name being trichlorethylidene glycol : — 

C 2 H 4 (OH) 2 CC1 3 CH(0H) 2 

Ethylene glycol. Trichlorethylidene glycol. 

Hydrous chloral fuses when heated, solidifies at about 120° F., boils 
at from 202° to 206° F. It sublimes as a white crystalline powder. 
Both chloral and chloral hydrate are soluble in water, alcohol, ether, 
and oils. Oils and fats are also soluble in chloral hydrate. The 
aqueous solution should be neutral and give no reaction with nitrate 
of silver. Chloral, especially if it contains a trace of acid, may 
undergo a spontaneous change into an opaque white isomeric modifi- 
cation, metachloral, insoluble in water, alcohol, or ether, but con- 
vertible by prolonged contact with water or by distillation into the 
ordinary condition. By action of weak alkalies chloral yields for> 
mate of the alkali-metal and chloroform : 

CCI3COH + KOH = H.CO.OK + CHC1 3 . 

Chloral, or rather strong aqueous solution of chloral hydrate (3 in 
4), injected beneath the skin yields nascent chloroform by action of 
the alkali of the blood, and produces narcotic effects (Liebreich, Per- 
sonne). Chloroform itself admits of similar hypodermic use (Rich- 
ardson). -If administered by the stomach, thirty to eighty grains of 
solid hydrate are required. The final products of the reaction of the 
chloroform and blood are formate and chloride of sodium. A strong 
spirituous solution of potash effects the same transformation : — 
CHCI3 + 4KOH = H.COOK + 3KC1 -f 2H 2 0. 

Solution of ammonia and moist hydrate of calcium, as well as 
weak solutions of fixed alkalies, convert hydrate of chloral into 
formate of the metal and chloroform. The reaction with the 
slaked lime being especially definite and complete (Wood), it 
may be employed in ascertaining the richness of a sample of 
commercial chloral hydrate in chemically pure chloral hydrate : — 

2(CC1 3 CII(0II) 2 ) + Ca20II == 2CIIC1 3 + (HCOO) 2 Ca + 211,0. 

L331 239 

From the foregoing equation and molecular weights it is 
obvious that 100 grains of hydrate of chloral, if quite dry, 
will yield by distillation with 30 grains of slaked lime and an 
ounce of distilled water (in a small flask and long bent tube 
kept cool by moistened paper) 72.2 grains of chloroform by 
weight or (the sp. gr. of chloroform being taken at 1.497) 
47. 5G grains by measure, or about 52 minims. UK) grains 



478 ORGANIC CHEMISTRY. 

of the official hydrate of chloral " should yield not less than 
70 grains of chloroform." (An} T such definite quantity of 
chloroform, on account of its volatile nature, is perhaps best 
measured, the weight being obtained by multiplying the 
volume by 1.5.) 

Small quantities of chloral hydrate in dilute solutions may be 
estimated by converting its chlorine into hydrochloric acid by 
nascent hydrogen, and titrating with volumetric solution of 
nitrate of silver (Short). A quantity of solution containing not 
more than .05 gram is placed in a small flask with granulated 
zinc and acetic acid, and allowed to stand twenty-four hours ; 
the solution is then poured off and the zinc washed two or three 
times with distilled water : a little red chromate of potassium is 
added, and it is then titrated with decinormal nitrate of silver 
solution in the usual way. the acetic acid and acetate of zinc not 
interfering with the indications. 1000 c.c. of the silver solution 
indicate 5.52. nearly, of chloral hydrate. 

Pure Chloral Hydrate. — Liebreich, who first proposed the use of 
chloral hydrate, gives the following as the characteristics of a pure 
article : Colorless, transparent crystals. Does not decompose by the 
action of the atmosphere, does not leave oily spots when pressed 
between blotting-paper, affects neither cork nor paper. Smells 
agreeably aromatic, but a little pungent when heated. Tastes 
bitter astringent, slightly caustic. Seems to melt on rubbing 
between the fingers. Dissolves in water like candy without first 
forming oily drops, and the solution is neutral or faintly acid to 
test-paper. Dissolves in bisulphide of carbon, petroleum, ether, 
water, alcohol, oil of turpentine, etc. Its solution in chloroform 
gives no color when shaken with sulphuric acid. Boiling-point, 
203° to 205° F. It volatilizes without residue. Distilled with sul- 
phuric acid, the chloral should pass over at 205° to 207° F. Melt- 
ing-point, 133° to 136° F.. again solidifying at about 120°. Gives 
no chlorine reaction on treating the solution in water (acidulated by 
nitric acid) with nitrate of silver. 

Impure Chloral Hydrate. — Yellowish, cloudy. Decomposes: leaves 
spots by pressing between blotting-paper : decomposes corks and paper 
of the packing. Smells pungent and irritating : on opening the bot- 
tle is sticky, and often emits fumes. Taste strongly caustic. With 
water forms oily drops or is partially insoluble. Boils at a higher 
temperature. On treating it with sulphuric acid turns brown, with 
formation of hydrochloric acid. Gives chlorine reaction on treat- 
ing the solution in water (acidulated by nitric acid) with nitrate of 
silver. 

Alcoholates of chloral are obtained on combining alcohols with 
chloral. Chloral alcoholate or trichlorethylidene ethyl ether, 

CCl 3 OH-<^p tt is obtained by mixing alcohol with chloral : it 

is, in fact, "chloral hydrate," with one hvdroxvl sroup replaced 
by (OCA). 

Bromal, CBr 3 COH, hydrate of bromah CBr 3 CH(OH) 2 . and alco- 



THE ACETIC AND LACTIC SERIES OF ACIDS. 479 

Jiolates of bromal, are produced when bromine instead of chlorine 
attacks alcohol. lodal, CI 3 COH, also exists. 

Butyl Chloral, C 3 H 4 C1 3 C0H, originally, but erroneously, termed 
croton chloral, is a product of the action of dry chlorine on cold alde- 
hyde. Its name expresses its constitution ; it is chlorinated butyric 
aldehyde — ordinary chloral being chlorinated acet-aldehyde. Butyl- 
chloral hydrate, croton-chloral hydrate, wrongly so called hydrate of 
butyl-chloral {Butyl-chloral Hydras, B. P.), hydrous butyl-chloral, 
C 3 H 4 C1 3 CH(0H) 2 (trichlorbulylidene glycol), occurs " in purely white 
crystalline scales, having a pungent but not acid odor, resembling 
that of hydrous chloral, and an acrid, nauseous taste. It fuses at 
about 172° F. (77.8° C.) to a transparent liquid, which in cooling 
commences to solidify at about 160° F. (71.1° C). Soluble in about 
fifty parts of water, in its own weight of glycerin and of rectified 
spirit, and nearly insoluble in chloroform. The aqueous solution is 
neutral or but slightly acid to litmus-paper. It does not yield chlo- 
roform when heated with solutions of potash or with milk of lime." 

The Acetic Series of Acids — continued. 

Propylic or Propionic Acid (ethyl-formic acid), C 2 H 5 COOH, is 
produced by oxidation of propylic alcohol. 

Butyric or Tctrylic Acid (propyl-formic acid), C 3 H 7 COOH, is 
formed by general methods ; also during the fermentation of 
cheese. It is found as a glyceric salt in butter (whence its 
name). 

Pentylic, Valerianic, or Valeric Acid, C 4 H 9 COOH. — There are 
several varieties of this acid, the valerianic acid from valerian 
and angelica root, and that artificially formed from amylic alco- 
hol {vide p. 450), being the iso-primary valerianic acid or iso-pro- 
pylacetic acid, CH(CH 3 ) 2 CII 2 .COOH, the primary having the con- 
stitution of CH 3 CII 2 CH 2 CH 2 .COOH. 

Palmitic Acid, C 15 H 31 COOH, from fats ; stearic acid, C 17 H 33 COOH, 
from suet ; cerotic acid, C 26 H 53 COOH, from beeswax ; and mclisslc 
acid, C 29 H 59 COOH, derivable from beeswax and from canauba wax 
(from the leaves of Copernicia cerifera, a Brazilian palm), all belong- 
ing to the acetic series. 

The Lactic Series. 

Acids of the Lactic Series, C n H 2n (OH)COOH.— This series is 
formed of hydroxyderivatives of the acetic series, one atom of 
hydrogen in the latter being replaced by the hydroxyl group : — 

CH 3 COOH CII 2 (OII)COOII 

Acetic acid. Hydroxyacetio or tdycollic acid. 

Though they possess only one carboxyl (C001I) group, yet, haying 
an alcoholic hydroxyl group, they form di-substitution-derivatives 
with the metals. 

They may be formed by partial oxidation of glycols by diluted 
nitric acid, and by acting on monochloro-derivatives oi' the acids 
of the acetic series by moist silver oxide. 



480 ORGANIC CHEMISTRY. 

2CH 2 C1.C00H -f- Ag 2 -f H 2 = 2CH 2 OH.COOH 4- 2AgCL 

Monocbloracetic acid. Gly collie acid. 

Carbonic Acid or Hydroxy formic Acid, OH.COOH, the first of this 
series, has been studied already. Carbamide or Urea, XH 2 .CO.XH 2 , 
the normal amide of carbonic acid, is interesting historically as beinc 
the first organic body synthetically produced from inorganic sources. 
(See Index, " Urea, artificial production of.") The acid amide of car- 
bonic acid, carbamic acid, XH 2 .CO.OH, occurs as an ammonium salt. 
NH 2 .C0.0NH 4 , in the carbonate of ammonium of pharmacy. The 
carbamate of ethyl, or urethane, XH 2 .CO.OC 2 H 5 . is a mild hypnotic. 
Glycollic Acid" ( Hydroxyacetic acid), CH 2 OILCOOH, is found in 
the leaves of the Virginia Creeper ; artificially it may be obtained 
by carefully oxidizing glycol and by the action of silver oxide on 
dextrose and lasvulose. 

Lactic Acid (Hydroxypropionic acid), C 2 H 4 (OH)COOH.— Three 
isomeric lactic acids are known ; the fermentative lactic acid (ethyl- 
idene* lactic acid), CH 3 CH.(OH)COOH ( see p. 344), and sarcolactic 
acid, from flesh, being those of importance. 

The Acrylic Seiies, 

Acids of the Acrylic Series, C n H 2n jCOOH. 

Acrylic Acid, C 2 H 3 COOH. or CH(CH 2 )COOH, is formed by oxi- 
dizing acrolein (acrylic aldehyde ; see Glycerin) by oxide of silver. 

Crotonic Acid, or methacrylic acid, C 3 II 5 COOH\ or CH(CHCH 3 )- 
COOH, formerly supposed to be a constituent of croton oil, may be 
formed by oxidizing crotonic aldehyde, and by acting on allyl cya- 
nide, C 3 H 5 CX, by water and hydrochloric acid : — 

C 3 H 5 CX + 2H 2 + HC1 = C 3 H 5 CO.OH -f XH 4 C1 

Oleic Acid, C 18 H 34 2 , or CH(C 16 H 32 )COOH, is found as a glyceric 
salt in many fats and oils. 

Preparation. — Olive oil is saponified with caustic potash, and 
the resulting soap decomposed by tartaric acid, which liberates 
oleic and stearic acids. The oleic and stearic acids are heated 
with lead oxide, forming lead oleate and stearate, the former 
being dissolved out from the latter by ether. The ether is 
evaporated and the lead oleate treated with hydrochloric acid, 
which liberates the oleic acid. 

Elaidic Acid (isomeric with oleic acid) is formed by passing nitro- 
gen peroxide into oleic acid ; it is more stable than oleic acid, dis- 
tilling unchanged. 

The Benzoic or Aromatic Series. 

Acids of Benzoic or Aromatic Series, C n II 2n _ 7 COOH. — The acids 
of this series are formed by oxidizing hydrocarbons, by oxidation 

* Bodies having the CH 3 CH group are called ethylidene compounds. 
Compare chloral hydrate, trichlore^/i'tfe?te glycol,Ca 3 CH.C(HO) 2 . 



RELATIONS OF SERIES OF ACIDS. 



481 





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482 ORGANIC CHEMISTRY. 

of alcohols of the benzylic series, and by acting on the cyanides of 
the members of the benzene series. All the acids of this series, 
with the exception of benzoic acid, possess many isomers. 

Benzoic Acid, C 6 H 5 COOH, occurs naturally in gum benzoin (Gum 
Benjamin), which contains from 12 to 15 per cent., the rest being 
mainly composed of two resins having the formulae C 40 H 46 O 9 and 
CggH^Oj. Benzoic acid may be obtained by oxidizing benzoic alde- 
hyde, C 6 H 5 COH, which may be prepared from trichloromethylben- 
zene (see Toluene, p. 427). Benzoene (toluene), C 6 H 5 CH 3 , may be 
directly oxidized into benzoic aldehyde, the methane group (CH 3 ) 
being resolved into COOH — evidence that benzoic acid is really a 
benzoene derivative, not a phenb'ene derivative. (For other modes 
of obtaining benzoic acid artificially see p. 335.) It may also be pro- 
duced from hippuric acid (benzamidacetic acid, p. 338). Benzoic 
acid heated with lime yields benzene : — 

C 6 H 5 COOH + CaO = C 6 H 6 + CaC0 3 

Benzoic acid. Benzene. Calcium 

carbonate. 

Benzoic Aldehyde or benzaldehyde, C 6 H 5 COOH, forms the greater 
part of oil of bitter almonds (see Amygdalin, p. 504). It is a col- 
orless liquid, soluble in 30 parts of water and in all proportions in 
ether and alchhol. With acid-sulphite of potassium it forms a crys- 
talline compound, C 6 H 5 .COH.NaHS0 3 . Benzoyl chloride, C 7 H 5 0C1, 
results from the action of chlorine on benzaldehyde (formerly termed 
benzoyl hydride, C 7 H 5 OH), or from the action of pentachloride of 
phosphorus on benzoic acid (benzoyl hydrate, C 7 H 5 OOH). Benzalde- 
hyde also results from the oxidation of the benzyl alcohol, C 7 H 7 OH, of 
balsam of Peru. 

The other acids of this series are unimportant. 

The Hydroxybenzoic Series. 

Acids of the Hydroxybenzoic Series, C n H 2I1 _ 8 OH.COOH. — Just as 
the acids of the lactic series are related to the acetic series, so are 
the acids of the hydroxybenzoic (or salicylic) series related to the 
benzoic series. 

CH 3 COOH CH 3 OH.COOH 

Acetic acid. Hyclroxyacetic or 

glycollic acid. 

C 6 H 5 COOH C 6 H 4 OHCOOH 

Benzoic acid. Hydroxybenzoic or 

salicylic acid. 

Salicylic or Hydroxybenzoic Acid, C 7 H 6 3 or C 6 H 4 OH.COOH 
(Acidum Salicylicum, II. S. P.). — Natural salicylate of methyl is 
described on p. 404. It also occurs in several species of violet (Man- 
delin). Salicylic acid may be made by the oxidation of salicylic alde- 
hyde (vide infra), or by the action of carbonic acid on phenol or car- 
bolic acid (Kolbe). To accomplish this, the phenol is mixed with 
caustic soda, forming sodium phenol or carbolate of sodium, C 6 H 5 OXa. 
The sodium phenol is then saturated with carbonic acid at the ordi- 
nary temperature, by which phenylcarbonate of sodium is produced. 



BENZOIC AND HYDROXYBENZOIC ACIDS. 483 

The latter on being heated in closed vessels is transformed into sali- 
cylate of sodium, from which salicylic acid may be obtained by the 
action of hydrochloric acid, and purification by recrystallization 
from alcohol. It appears to be identical with the natural acid. 

C 6 H 5 .ONa -f C0 2 = C 6 H 5 O.CO.ONa 

Sodium phenol or Phenylcarbonate of 

carbolate of sodium. sodium. 

C 6 H 5 O.CO.ONa = C 6 H 4 OH.CO.ONa 

Phenylcarbonate of sodium. Salicylate of sodium. 

C 6 H 4 OH.CO.ONa + HC1 = C 6 H,OH.CO.OH -f NaCl 

Salicylate of sodium. Salicylic acid. 

Salicylate of Phenyl, C 6 H 4 OH.CO.OC 6 H 5 , or salicylic phenol — or, 
shortened, salol — is a new antiseptic, antipyretic, antirheumatic 
remedy. It is white, crystalline, soluble in alcohol, insoluble in 
water, and of an aromatic odor. 



Table showing the Relations between the Benzoic and 
Hydroxybenzoic Acids. 



Benzoic acid. . C 6 H 5 .CO.OH. 

Hydroxybenzoic or salicylic acid . . . C 6 H 4 OH.CO.OH. 

Dihydroxybenzoic acid C 6 H 3 (OH) 2 .CO.OH. 

Trihydroxybenzoic or gallic acid . . . C 6 H 2 (OH) 3 .CO.OH. 



Salicylic acid, like carbolic acid, is a powerful antiseptic, but is 
free from" the taste and smell of carbolic acid. It is only slightly 
soluble in cold water, but readily soluble in hot water, alcohol, ether, 
and in aqueous solutions of such alkali-metal salts as borax, phos- 
phate of sodium, or citrate of potassium, which it converts into acid 
salts, with formation of a salicylate. A similar antiseptic cresotic 
acid (hydroxytoluic acid, C 6 II 3 QH.CII 3 .COOII) is similarly obtained 
from cresol or cresylic acid, C 6 H 4 OII.CH 3 . Ferric chloride strikes a 
violet coloration with both salicylic and cresotic acids. Both acids 
have antipyretic powers. The true salicylates of the alkali-metals, 
and probably therefore the cresotates, are very feeble antiseptics. 
Salicylate of sodium, Sodii Salicylas, B. P., (NaC ! II 5 3 ). 2 ,II. 2 0, the 
old Salicylate of Soda, made by neutralizing salicylic acid with 
hydrate or carbonate of sodium, forms small, nearly colorless lamel- 
lar crystals, soluble in alcohol and readily soluble in water. Car- 
bolic acid, often containing cresylic acid, commercial salicylic acid, 
may contain cresotic acid. An alcoholic solution of salicylic acid 
allowed to evaporate spontaneously, exposure to dust being avoided, 
should leave a white residue free from color even at the points of the 
crystals. Salicylic acid is soluble in strong sulphuric acid, yielding 
mlpho-salicylic acid, C ? H 4 (OH)CO.O.S0 8 H. Salicylic acid yields 
colored substances on being nitrated and etherified, etc. Todosalicylic 
acid and, di-iodosalicylic acid, C 7 H 6 I0 3 and C 7 H 4 I 2 Q 3 , are used in 
medicine. 



484 ORGANIC CHEMISTRY. 

Salicylic Aldehyde, or hydroxybenzoic aldehyde, CgH^OH.COH 
(salicylous acid, hydride of salicyl). — Found in the essential oil 
of meadow-sweet (Spirea ulmaria) ; also obtained by the oxidation 
of saligenin (see p. 496). It may be artificially formed by the action 
of chloroform on sodium phenol. 

Preparation. — Mix 10 parts of phenol with 20 parts of 
sodium hydrate, dissolved in 30 parts of water in a flask 
having an upright condenser, and gradually add 20 parts of 
chloroform. After heating the flask on a water-bath for half 
an hour, add excess of hydrochloric acid, when a red-violet oil 
will rise to the surface. Pour the contents of the flask into 
a retort, and pass steam through it till no more aldehyde 
comes over. The reaction is as follows : — 

C 6 H 5 ONa + 3NaOH + CHC1 3 = C fi H,ONa.COH + 3NaCl + 2H 2 0. 

Sodium Chloroform. Sodium salicylic 

phenol. aldehyde. 

This, treated with hydrochloric acid, gives : — 

C 6 H 4 ONa.COH + HC1 = C 6 H 4 (OH)COH + NaCl. 

Sodium salicylic aldehyde. Salicylic aldehyde. 

The oil which passes over (orthohydroxybenzoic aldehyde) may 
be purified from phenol (with which it is always contaminated) by 
treating with acid sulphite of sodium, which forms a compound 
with aldehyde, leaving the phenol, which may be removed by dis- 
solving in ether. An isomeric salicylic aldehyde (parahydroxyben- 
zoic aldehyde) is formed with the ortho-aldehyde, and remains dis- 
solved in the water in the retort, from whence it is precipitated on 
cooling. 

Coumarin, C 9 H 6 C 2 (the principle of the Tonka bean), may be 
obtained by acting on the sodium-derivative of salicylic aldehyde 
with acetic anhydride and sodium acetate (Perkin). 

The Trihydroxybenzoic Series. 

Acids of the Trihydroxybenzoic Series (C n II 2n _ I0 (OH) 3 COOH). 
Gallic Acid, or trihydroxybenzoic acid, C 6 H 2 (01I) 3 COOH (see p. 
358).— By the elimination of one molecule of water from two 
molecules of gallic acid, tannic acid is produced. 

rr jcoom (C00H 

L «*M (OH) 3 

n XT f COOH 

^e tt 2 J ( H) 3 



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CO I + H 9 



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. (OH), 

Tannic acid. 

Gallotannic acid or tannin (see p. 356) by heat yields pyrogallol or 
pyrogallic acid and carbonic anhydride. 

C 6 ir 2 (OH) 3 CQOH = C,H 3 (OH) 3 + C0 2 . 






dNNAMIC ACID. 485 

The Cinnamic Series. 

Acids of the Cinnamic Series, C n H 2ll _ 9 COOH. — Cinnamic acid, 
C 8 H 7 COOH, may be obtained from the balsams of Tolu, Peru, and 
storax. 

1. Balsam of Peru {Balsamum Peruvianum, U. S. P.), an exuda- 
tion from the trunk of Tohiifera Pereira, is a mixture of oily mat- 
ter with about one-quarter or one-third resinous matter and G per 
cent, of cinnamic acid. The oil, by fractional distillation in an 
atmosphere of carbonic acid gas and under diminished pressure, 
furnishes benzyl hydrate or benzylic alcohol (C 6 H 6 CH 2 OH), henzoate 
of benzyl (C 6 H 5 CO.OC 7 H 7 ), and cinnamate of benzyl (C g II 7 CO.OC 7 H 7 ) 
or cinnamein (Kraut). By action of alcoholic solution of potash it 
yields benzoate and cinnamate of potassium and benzylic alcohol ; 
also cinnamic alcohol (C 8 H 7 CH 2 OH), otherwise -known as iperuvine 
or styrone; it also often holds in solution metacinnamein or styracin 
(C 18 H 16 2 ), isomeric with cinnamic aldehyde (C 8 H 7 COH). The resin 
of balsam of Peru seems to result from the action of moisture on 
the oil. Any admixture of resin, oil, storax, benzoin, or copaiva 
with balsam of Peru is detected by mixing six grains of slaked 
lime with ten drops of the balsam, when a soft product results if 
the specimen be pure, but hard if impure ; further, the mixture, on 
being warmed until volatile matter is expelled and charring com- 
mences, gives no fatty odor. 2. Balsam of Tolu {Balsamum Tolu- 
tanum, U. S. P.) is an exudation from the trunk of Tohiifera bal- 
samum ; in composition it closely resembles balsam of Peru, but is 
more susceptible of resinification. It contains benzoate and cin- 
. namate of benzyl, cinnamic acid, a little benzoic acid. (Busse), and 
about 1 per cent, of a volatile hydrocarbon, lo.lene, C 10 H l6 . The 
cinnamic acid crystals may be seen with a lens when a little of the 
balsam is pressed between two warmed pieces of glass. Old hard 
balsam of Tolu is a convenient source of cinnamic acid, which may 
be extracted by the same process as that by which benzoic acid is 
obtained from benzoin — namely, ebullition with alkali, filtration, 
and precipitation by hydrochloric acid. 3. Storax (Styrax, U. S. P.) 
is an oleo-resin obtained from the Liquidambar orientate. It con- 
tains a volatile oil termed styrol, cinnamene. or cinnamol (C 8 II 8 ) — 
which possibly (Berthelot) is condensed acetylene, 4C 2 H 2 — cinnamic 
acid, styracin, or cinnamate of cinnamyl (C 8 H 7 CO.OC 9 H 9 ), and a soft 
and a hard resin. Styrol differs from similar hydrocarbons in being 
converted into a polymeric solid termed metastyrol or draconyl on 
heating to about 400 F. For medicinal use, Storax {Styrax Prce- 
paratus, B. P.) is purified by solution in alcohol, nitration, and 
removal of the alcohol by distillation. By oxidation with red chro- 
mate of potassium and sulphuric acid it yields an odor resembling 
that of essential oil of bitter almonds. 



I) i basic Acids. 



Dibasic Acids are acids having two carboxyl (CQOH) groups 
the molecule. 



486 ORGANIC CHEMISTRY. 

The Succinic Series. 

Acids of the Succinic Series, C n II 2n (COOH) 2 . — These acids may 
be formed by the oxidation of glycols, or by the action of water 
and hydrochloric acids on the cyanides of the defines, obtained by 
acting on the define dibromo-additive derivatives by potassium 
cyanide. 

Oxalic Acid, C 2 4 H 2 or (COOH) 2 , is the first of this series. It 
may be obtained by oxidizing glycol, C 2 H 4 (0H) 2 : — 

CH 2 OH COOH 

I + 20 2 = | + 20H 2 . 

CH 2 OH COOH 

Glycol. Oxalic acid. 

Also by the action of carbonic anhydride on metallic sodium : — 
2C0 2 + Na 2 + C 2 4 Na 2 

Carbonic anhydride. Sodium. Sodium oxalate. 

(For other methods, see Oxalic Acid, p. 315.) 
Oxamide, C 2 4 (NH 2 ) 2 , the analogue of urea (Carbamide, C0(NH 2 ) 2 ), 
is formed on mixing oxalate of ethyl with ammonia. 
Succinic Acid, C 2 H 4 (COOH) 2 . See p. 355. 

The Malic Series, 

Acids of the Malic Series, C n H 2n _ 1 OH(COOH) 2 .— Malic or hy- 
droxysuccinic acid, C 2 H 3 (OH)(COOH) 2 , is obtained artificially by 
acting on bromosuccinic acid, C 2 H 3 Br(COOH) 2 , with moist silver 
oxide, the bromine being replaced by hydroxyl. It is contained 
in unripe mountain-ash berries, morello cherries, etc. (See p. 
348.) 

CON1T 

Asparagine (amidosuccinamic acid), CjHgNH^^^^TT 2 . (See p. 

349.) 

The Tartaric Series. 

Acids of the Tartaric Series, C n H 2 n2 (OH) 2 (COOH) 2 . — Tartaric 
Acid (dihydroxysuccinic acid), C 2 H 2 (OH) 2 (COOH)o, may be obtained 
by oxidizing erythrite, C 2 H 2 (OH) 2 (CH 2 OH) 2 . (See p. 467. For 
other modes of formation, see p. 315.) There are four isomeric 
tartaric acids, differing by their action on a ray of polarized 
light. 

The Phthalic Series. 

Acids of the Phthalic Series, C n H n2 _ 8 (COOH) 2 . — Phthalic Acidi 
C 6 H 4 (COOH) 2 , is obtained by the oxidation of naphthalene and 
naphthalene dichloride, or a mixture of benzene and benzoic acid. 
By distillation it forms phthalic anhydride, C 8 H 4 3 , which when 
heated with phenol and sulphuric acid yields phenolphthalein, a 
light-yellow crystalline powder, which when dissolved in alcohol is 
used in alkalimetry for its property of turning brilliant red with 
the slightest excess of alkali. 



RELATIONS OF SERIES OF ACIDS. 



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488 ORGANIC CHEMISTRY. 

Tribasic Acids. 

Tribasic Acids, having three carboxyl (COOH) groups in the 
molecule. — Tricarbalhjlic Acid, or propane-tricarboxylic acid, C 3 H 5 - 
(COOH) 8 , is the first of this series ; its hydroxy-derivative, citric 
acid, C 3 H 4 (OH)(COOH) 3 , (hydroxy-propane-tricarboxylic acid), found 
in fruits, has already been described (see p. 323). 

Other Polybasic Acids. 

Tetrabasic Acids (as pyroinellitic acid, C 6 H 2 (COOH) 6 ) and liexa- 
basic acids (as mellitic acid, C(COOH) 6 ) are known. 



QUESTIONS AND EXERCISES. 

791. Give general methods for the formation of aldehydes and 
acids. 

792. How is acetaldehyde prepared? 

793. Describe the reactions that occur in the manufacture of 
chloral and chloral hydrate. 

794. What is the nature of the action of alkalies on chloral 
hydrate ? 

795. Mention the characters of pure and impure chloral hydrate. 

796. What relation has valerianic acid to amylic alcohol? 

797. Give the relations between the acetic and lactic series of 
acids. 

798. To what series do the following acids belong : — Oleic, butylic, 
oxalic, and citric ? 

799. How is benzoic acid prepared ? Give the differences between 
balsam of Peru, Tolu, and gum benzoin. 

800. How is oil of bitter almonds prepared, and how can it be dis- 
tinguished from so-called artificial oil of bitter almonds? 

801. Give artificial methods of preparing salicylic aldehyde and 
acid. 

802. Give the systematic names of tartaric, succinic, carbonic, 
salicylic, and citric acids. 



KETONES. 

Just as primary alcohols on losing hydrogen yield aldehydes, so 
secondary alcohols (see p. 438) on losing hydrogen yield ketones : — 

C n H 2n+1 CH 2 OH — H 2 ~= C n H 2n+1 COH 

(C n H 2n+1 ) 2 CHOH - H = (C n H 2n+1 ) 2 CO 

Like aldehydes, ketones are converted by nascent hydrogen into 
the corresponding alcohols. Like aldehydes, ketones form crystal- 
line compounds with acid sulphites. While, however, aldehydes by 
oxidation yield corresponding acids, ketones break up and yield acids 
whose molecules have a smaller number of carbon atoms. 



GLUCOSIDES. 489 

Acetone, C 3 H 6 0, or dimetJujl-Jcetone, (CH 3 ) 2 CO or CH 3 .CO.CH 3 , the 
original and best known of the class, may be obtained by strongly 
heating acetate of calcium, carbonate of calcium remaining. The 
calcium salts of other fatty radicals split up in a similar manner 
(hence perhaps the name, from keu, ked, to split, and the original 
acetone), yielding other ketones, as propione, butyrone, valerone, etc. 

(CH 3 COO) 2 Ca = (CH 3 ) 2 CO + CaC0 3 

Acetate of calcium. Acetone. Carbonate of calcium. 



Note. — There are many organic substances the composition of 
which has been established, and the characters of which are definite, 
whether basic, acid, or neutral, but whose constitution is still so 
questionable that they cannot yet be classified with the hydrocar- 
bons and derivatives of hydrocarbons. These are the glucosides, 
alkaloids, albuminoids, certain coloring-matters, etc. They are 
described in the following pages. 



THE GLUCOSIDES. 



Source. — The Glucosides are certain proximate vegetable princi- 
ples which, by ebullition with dilute acid or other method of decom- 
position, take up the elements of water and yield glucose, accom- 
panied by a second substance, which differs in each case according 
to the body operated on. Several of the glucosides which are of 
pharmaceutical interest will now be considered. Tannin, or tannic 
acid, is .also a glucoside ; it has been described among the acids. 

There are indications that all glucosides may be regenerated from 
the bodies into which they are converted by heat. 

Note on Nomenclature. — The first syllable of the names of gluco- 
sides and neutral principles generally are commonly given in allu- 
sion to origin ; the last syllable is in, which sufficiently distinguishes 
them as a class. 

Amygdalin (C 20 H 27 NO n ,3H 2 O). — This body, obtained by 
Robiquet and Boutron-Charlard in 1830, was the first discov- 
ered glucoside (Liebig and Wohler, 1837). It is a white crys- 
talline substance, existing in the bitter (Amygdala Amara, V. 
S. P.) but not in the sweet almond (Amygdala Dulcis, U. 8. 
P.). About 2 per cent, is readily extracted by strong alcohol 
from the cake left when the fixed oil has been expressed from 
bitter almonds. From the concentrated alcoholic solution ether 
precipitates the amygdalin. 

Make an emulsion of two or three sweet almonds by bruis- 
ing and rubbing them with water, and notice that it has no 
odor of essential oil of bitter almonds; add a grain or two of 
amygdalin: an odor of essential oil of bitter almonds is at once 
developed. Bruise two or three bitter almonds and rub with 



490 ORGANIC CHEMISTRY. 

water; the volatile oil is again developed (Oleum Amygdalae 
Amarse, U. S. P.). Sp. gr. 1.060 to 1.070. 

Bitter-almond water {Aqua Amygdala? Amarce, U. S. P.) is made 
by filtering a mixture of 1 part of the oil with 999 parts of distilled 
water. The source of the benzaldehyde, or essential oil of bitter 
almonds, in these reactions is the amygdalin, which, under the 
influence of synaptase or emulsin (a nitrogenous, casein-like ferment 
existing in both bitter and sweet almonds) splits up into the essen- 
tial oil, hydrocyanic acid, and glucose : — 

C 20 H 27 NO U + 2H 2 = C 6 H 5 COH + HCN + 2C 6 H 12 6 

Amygdalin. Water. Benzaldehyde. Hydrocyanic Glucose. 

acid. 

As each molecule of amygdalin yields one of hydrocyanic acid, a 
simple calculation shows that 17 grains (mixed with emulsion of 
sweet almonds) will be required to form 1 grain of real hydrocyanic 
acid — a quantity equivalent to 50 minims of the diluted hydrocyanic 
acid of the British Pharmacopoeia. The hydrocyanic acid is probably 
in chemical combination with the oil to the extent of about 5 per cent. 
According to Linde, the production of the benzaldehyde is preceded 
by the formation of benzaldehydcyanhydrin, C 6 H 5 CH(OH).CN. The 
emulsin and amygdalin occur in different parts of the bitter almond. 

Test. — The reaction between synaptase and amygdalin is applica- 
ble as a test of the presence of one by the addition of the other, 
even when mixed with much organic matter. 

Jacobsen obtains true benzaldehyde artificially from benzodichlo- 
ride (dichloromethylbenzene, C 6 H 5 CHC1 2 ), one of the dichlorotolu- 
enes, by heating with glacial acetic acid and chloride of zinc with a 
little water. 

Cherry-Laurel Water {Aqua Laurocerasi, B. P., by distillation 
with water from Laurocerasi Folia, B. P.) contains hydrocyanic acid 
derived from a reaction similar to — indeed, probably identical with — 
that described above, for bitter almond oil is simultaneously produced. 
But the proportion of amygdalin or analogous body in cherry-laurel 
leaves is most variable ; hence normally the strength of the water is 
highly uncertain. It may contain perhaps 2 to 4 parts of hydrocy- 
anic acid in 10,000. The British Pharmacopoeia, however, directs 
that it shall contain 0.1 per cent, of real hydrocyanic acid, it being 
strengthened by the addition of hydrocyanic acid, or if necessary, 
diluted by the addition of distilled water, until it has the prescribed 
strength. 

Prunus Virginiana, U. S. P., the bark of Prunus serotina or 
Cerasus serotina, the Wild Black Cherry Bark, also furnishes by dis- 
tillation an essential oil and hydrocyanic acid ; quince-seeds also 
{Cydonia vulgaris). The Wild Black Cherry contains amygdalin. 

Caution. — Essential oil of almonds is of course highly poisonous. 
The purified oil or benzaldehyde is almost innocuous ; it is obtained 
on distilling the crude oil with milk of lime and ferrous chloride, 
and drying the product by shaking with fused chloride of calcium. 
The so-called "artificial oil of bitter almonds" or " nitrobenzol " 
[C 6 H 5 N0 2 ], when taken in quantity, has been known to produce 



GLUCOSIDES. 491 

death. The presence of nitre-benzol in oil of bitter almonds is 
detected by adding a little of the oil to a mixture of zinc and diluted 
sulphuric acid, shaking well, setting aside for an hour or two, filter- 
ing off the clear liquid, and adding a little chlorate of potassium ; a 
violet color (actual mauve) is produced. The reaction is due to the 
formation of phenylamine or aniline (see p. 427). Or the specimen 
may be shaken with bisulphite of sodium (for all such aldehydes 
form a compound with bisulphite of sodium) to fix the essential oil, 
and then with ether, which dissolves out, and on evaporation will 
yield the nitrobenzol. 

Arbutin (C 25 II 34 14 ,II 2 0) is contained in the leaves of Arcto- 
staphylos uva ursi and Chimapliila umbellata (Chimaphila, U. S. P., 
or Pipsissewa), and many ericaceous plants. It is a bitter neutral 
body occurring in acicular crystals, and resolvable by acids into 
hydrokinone (C 6 H 6 2 ) and glucose, and by gentle oxidation into 
kinone (C 6 H 4 2 ) and formic acid. Ericolin (C 34 H 56 21 ) is another 
bitter glucoside in bearberry-leaves. 

Bryonia (C 48 H 80 O 19 , Walz). — The colorless, bitter, indistinctly 
crystalline principle of Bryony (Bryonia, U. S. P., the root of 
Bryonia alba and Bryonia dioica). 

Cathartic Acid. — " The glucoside acid that now is known to 
confer on the Senna of Alexandria (from Cassia acutifolia) and 
of India (from Cassia elongata) (Senna, U. S. P.) its purgative 
property has been named by its discoverers (Dragendorff and Kubly) 
cathartic acid. Its formula has been stated as C 180 H 192 N 4 SO 82 , which, 
if true, accounts for its extreme instability. It is insoluble in water, 
strong alcohol, and ether, but enters readily into either solution when 
combined with alkaline and earthy bases, in which state it exists in 
senna. Its ammonium salts give brownish flocculent precipitates 
with salts of silver, tin, mercury, copper, and lead. Antimonial 
salts, tannin, and yellow and red prussiates have no effect upon it. 
Alkalies, aided by heat, act destructively upon it. Boiled with 
a mineral acid, it splits into a peculiar kind of glucose and an 
acid that has been named cathartogenic ; its formula is said to be 
C 132 H 116 N 4 S0 44 . The natural cathartate occurring in senna is pre- 
pared by partially precipitating by strong spirit a watery infusion 
of senna, concentrated to a syrupy state by evaporation in vacuo. 
The filtrate is now treated with a much larger bulk of absolute 
alcohol, and the precipitate thus obtained is purified by repeated 
solution in water and precipitation by alcohol. To obtain the pure 
acid, advantage is taken of its colloidal properties ; the crude cathar- 
tate is dissolved in moderately strong hydrochloric acid, and sub- 
jected to dialysis on a diaphragm of parchment paper. The min- 
imum dose of this pure acid was found to be about \\ grains, which 
caused several stools with decided griping. 

" The cathartic combinations that 1 have made are — the cathartate 
of ammonium, prepared from cathartate of lead by my original pro- 
cess, and the mixed cathartates, prepared according to Dragendorff's 
method as modified by myself. Of the former nearly pure salt. I 
have found 3f grains to purge (airly as to amount, but slowly as to 
time, and with considerable griping. 01' the latter, "•: grains purged 



492 ORGANIC CHEMISTRY. 

violently with much griping and sickness, which continued through 
the greater part of the day. It obviously would be improper to 
combine senna with any of its metallic precipitants, should such be 
desired, which is not likely. It is here satisfactory to observe that 
the cathartate of magnesium is soluble, and that the old-fashioned 
black draught agrees with new-fashioned science" (Groves). 

Buckthorn-juice {Rhamni Succus, B. P.) owes its cathartic proper- 
ties to a substance apparently identical with cathartic acid. Pos- 
sibly the purgative properties of the bark of the Rhamnus Frangula 
{Frangula, U. S. P.), Black Alder, Buckthorn, also are due to 
cathartic acid. . 

Colocynthin (C 56 H 84 23 ?). — This substance is the active bitter 
and purgative principle of colocynth-fruit {Colocynthis, U. S. P.): 
it is soluble in water and alcohol, but not in ether. By ebullition 
with acids it furnishes glucose and a resinoid body. 

Convolvulin. — See Jalapin. 

Cotoin (C 22 H 18 6 ) appears to be the chief active principle of Coto- 
bark, a Bolivian remedy for diarrhoea. 

Daphnin (C 31 H 34 19 ) is the crystalline glucoside of the bark of 
Daphne mezereum (Mezerei Cortex, B. P.). Boiled with dilute acids, 
it yields daphnetin (C 19 H u 9 ) and glucose. The acrid principle of 
mezereon is resinoid. 

Digitalin (C. 27 H 45 15 , Kosmann ; C 5 H 8 2 , Schmiedeberg). — This 
is an active principle of the Foxglove {Digitalis, U. S. P.). On 
boiling a grain of digitalin with diluted sulphuric acid for some 
time, flocks of digitaliretin (C 15 H 25 3 ) separate, and glucose may 
be detected in the liquid : — 

C 27 H 45 15 + 2H 2 = C 15 H 25 5 + 2C 6 H 12 6 

Digitalin. Water. Digitaliretin. Glucose. 

Properties. — Digitalin occurs "in porous mammillated masses or 
small scales, white, inodorous, and intensely bitter, readily soluble 
in spirit, but almost insoluble in water and in pure ether ; dissolves 
in acids, but does not form with them neutral compounds ; its solu- 
tion in hydrochloric acid is of a faint yellow color, but rapidly 
becomes green. It leaves no residue when burned with free access 
of air. It powerfully irritates the nostrils and is an active poison." 
According to Pettenkofer, " an intense red color is produced if a 
trace of digitalin dissolved in water is mixed with a weak aqueous 
solution of inspissated bile, and sufficient oil of vitriol added to 
raise the temperature to 158° F." Moistened with sulphuric acid 
and the liquid exposed to the vapor of bromine, a violet color is 
produced. 

Process. — The process for the preparation of digitalin consists in 
dissolving the glucoside out of the digitalis-leaf by alcohol, recover- 
ing the alcohol by distillation, dissolving the residue in water by 
the help of a small quantity of acetic acid, removing much of the 
color from the solution by animal charcoal, neutralizing most of the 
acetic acid by ammonia, precipitating the digitalin by tannic acid 
(with Avhich it forms an insoluble compound), washing the precip- 
itate, rubbing and heating it with spirit and oxide of lead (which 



GLUCOSIDES. 493 

removes the acid in the form of. insoluble tannate of lead), again 
decolorizing by animal charcoal, evaporating to dryness, washing 
out impurities still remaining by ether, and drying the residual 
digitalin. In this form digitalin is uncrystallizable, and is somewhat 
indefinite. 

Pure Digitalin (?'). — On treating commercial digitalin with chloro- 
form only an inert substance remains undissolved. The solution 
yields pure digitalin on evaporation ; it may be crystallized from 
spirit in radiating needles (Nativelle). The therapeutic effect of 
the pure substance is identical with the preparations of digitalis, 
but, as might be expected, more constant in its action, and, of course, 
intensely powerful. 

Digitoxin (C 31 H 33 7 ) (C 21 H 32 7 , Dragendorff) is a highly poison- 
ous substance extracted from Foxglove by Schmiedeberg. The same 
chemist regards commercial digitalin from foxglove-seeds as com- 
posed of varying proportions of three glucosides — namely, pure 
active digitalin (C 5 H 8 2 ), digitonin (C 31 H 52 17 , closely allied to 
saponin), and digitalein, with inactive digitalin or digitin. 

Elaterin (C 26 H 28 5 ). — Boil elaterium, the dried sediment from the 
juice of the squirting-cucumber fruit (Ecballium, Elaterium), in a 
small quantity of spirit of wine, and filter; fibrous and amylaceous 
matters remain insoluble, while elaterin and resin are dissolved. 
The filtrate, concentrated and poured into a warm solution of pot- 
ash, yields, on cooling, crystals of elaterin, resin being retained by 
the alkali.* It is purified by recrystallization from spirit {Elaterin. 
U. S. P.). 

Elaterin is probably not a true glucoside. It does not always 
respond to the test for glucose after boiling with acids ; and when 
it does the reaction is possibly due to prophetin, a glucoside stated 
by Walz to be present in elaterium. 

Elaterin is the active principle of the so-called elaterium. Elate- 
rium occurs " in light, friable, slightly-incurved cakes, about one 
line (^2 inch) thick, greenish-gray, acrid and bitter ; fracture finely 
granular." Good specimens of this drug should yield not less than 
20 per cent, of elaterin. Elaterium adulterated with chalk and other 
substances was formerly occasionally met with. A trituration of 
Elaterin is official (Trituratio Elaterini). It is a mixture of 1 part 
of elaterin with 9 of sugar of milk. 

The best method of obtaining elaterin is to exhaust elaterium with 
chloroform, evaporate, and then to add ether to the residue, when 
crystalline elaterin remains. It should be washed with a little ether 
and crystallized from chloroform. When pure it occurs in hexagonal 
scales or prisms. 

Test. — A little is placed in a watch-glass with a drop or two of 
liquefied carbolic acid, and then two or three drops of strong sul- 
phuric acid: a carmine color is developed (Lindo). 

Gentiopicrin or Gentian bitter (C 20 H S0 O 12 ), the neutral crystal- 

*" The alcoholic solution should not be precipitated by tannic acid 
nor by salts of mercury or of platinum (abs. of, and difference from, 
alkaloids)." 



494 ORGANIC CHEMISTRY. 

line principle of the root of Gentiana lutea (Ge?itiance Radix, B. P.). 
It is soluble in water and weak spirit. Alkalies decompose it. Dilute 
acids convert it into gentiogenin and glucose. Gentian-root also con- 
tains a variety of tannin and a crystalline acid (1IC U H 9 5 ) termed 
gentianic or gentisic acid, or gentisin. Fused potash, etc. gives 
with the latter an acid (C 7 H 6 OJ, which has also, unfortunately, 
been called gentisic acid. 

Gltcyrrhizin (C 2i H 36 9 , Gorup-Besanez) or Ghjcyrrhizic Acid 
(C 44 H 63 N0 18 , Habermann). — Liquorice-root (Glycyrrhiza, U. S. P.), 
in addition to uncrystallizable sugar, contains 3 or 4 per cent, of 
a sweet substance, glycyrrhizin, which, when boiled with hydro- 
chloric acid or diluted sulphuric acid, yields a resinoid bitter body, 
glycyrretin, and an uncrystallizable sugar resembling glucose. Gly- 
cyrrhizin is only slightly soluble in cold water, but is taken up by 
diluted alcohol containing a little ammonia (Extr actum Glycyrrhiza^ 
Fluidum, U. S. P.) or by ammoniacal water. An infusion of the lat- 
ter, evaporated to a pilular consistence, forms Extr actum Glycyr- 
rhizo3 Purum, TJ. S. P. It is present in considerable quantity in 
the evaporated decoction (Stick Liquorice, Spanish Liquorice, or 
Solazzi Juice). The tropical substitute for liquorice is the root 
of Abrus precatorius or Indian Liquorice (Abri Radix, P. I.), the 
hunch or gunj of Bengal, the ratti of Hindustan, and the jequirity 
of Brazil, which also apparently contains glucose and glycyrrhizin. 
(The seeds yield by maceration a substance which acts as a poison 
when injected into the blood, but not when swallowed. Warden 
and Waddell regard the active principle as an albuminoid and term 
it abrin. Bruylants and Yenneman consider it to be a product of 
germination and call it jequeritin. Bechamp and Dujardin regard 
the latter as a mixture of legumin and jequirityzymose.) Glycyr- 
rhizin has considerable power of disguising nauseous flavors. Rous- 
sin refers the sweet taste of liquorice not to pure glycyrrhizin, but 
to a combination of glycyrrhizin with alkalies, and states that am- 
moniacal glycyrrhizin has exactly the sweetness of liquorice-root. 
The formula of this glycyrrhizate of ammonium is said by Haber- 
mann to be (NH 4 ) 3 C 44 H 60 XO l8 . Sestini finds that the glycyrrhizin 
of liquorice-root is chiefly glycyrrhizate of calcium. 

An ammoniated glycyrrhizin (Glycyrrhizinum Ammoniatum, U. 
S. P.) is directed to be prepared by precipitating a dilute ammoniacal 
percolate with sulphuric acid, washing, redissolving in ammoniacal 
water, reprecipitating, again washing, dissolving in solution of am- 
monia, and spreading on glass plates to dry until reddish-brown 
scales are obtained. 

Guaiacix. — Resin of Guaiacum (Guaiaci Resina, U. S. P.), an 
exudation from the wood (Guaiaci Lignum, U. S. P.) of Guaiacum 
officinale, is probably a mixture of several substances, among which 
are Guaiaretic or Guaiaretinic acid (C 20 H 2fi O 4 , Hlasiwetz), Guaia- 
conic acid (C 38 H 40 O 10 , Hadelich), and Guaiacin, a glucoside. On 
boiling guaiacum resin with diluted sulphuric acid for some time, 
glucose is found in the liquid, a green resinous substance (guaiare- 
tin) remaining insoluble (Kosmann). Most oxidizing agents, and 
even atmospheric air, especially under the influence of certain 



GLUCOSIDES. 495 

organic substances, produce a blue, then green, and finally a brown 
color when brought into contact with an alcoholic solution of 
guaiacum resin. 

These effects are said to be due to three stages of oxidation (Jonas). 
They may be observed on adding the solution to the inner surface of 
a paring of a raw potato. 

Helleborin (C 36 H 42 6 ) and Helleborein (C 26 H 44 15 ) are crystal- 
line glucosides occurring in the roots of Black Hellebore (Helleborus 
niger) or Christmas Rose, and Green Hellebore (H. viridis), ranun- 
culaceous herbs. 

Jalapin (C 31 H 50 O 16 ) and Convolvulin (C 34 H 56 16 ). — According to 
Keyser and Meyer, jalap resin contains two distinct substances — con- 
volvulin, chiefly obtained from Mexican male jalap (Ipomcea orizaben- 
sis), and jalapin, most largely contained in the true jalap (Ipomcea 
purga) ; the former is soluble in ether, the latter insoluble. Boil jalap 
resin with diluted sulphuric acid for some time, and filter ; a substance, 
which is probably a mixture of jalapinol (C 13 H 24 3 ) and convolvulinol 
(C 16 H 30 O 3 ), separates, and glucose may be detected in the clear liquid. 
(It is to be regretted that the authors transpose the above names, 
terming the old well-known jalapin convolvulin.) 

C 31 H 50 O 16 + 5H 2 = C 13 H 2 A + 3C 6 H 12 6 

Jalapin. Water. Jalapinol. Glucose. 

Jalapic Acid. — This is contained in the portion of jalap resin solu- 
ble in ether. It may also be obtained from jalapin by ebullition 
with alkalies : — 

2C 3] H 50 O 16 + 3H 2 = C 62 H ]06 O 35 

Jalapin. Water. Jalapic acid. 

Jalap Resin (Resina Jalapse, U. S. P.) is obtained by digest- 
ing and percolating jalap-tubercles (Jalapa, U. S. P.), with 
spirit of wine, adding a little water, distilling off the spirit, 
pouring away the aqueous portion, which contains much sac- 
charine matter, and washing and drying the residual resin. 
Jalap, thoroughly exhausted by this process, should furnish, 
according to the United States Pharmacopoeia, not less than 12 
per cent, of resin, of which resin. (Restna Jalapse, U. S. P.) not 
more than one-tenth should be soluble in ether — a test which 
excludes the so-called "Tampico" jalap, the resin of which is 
soluble in ether. The tincture of jalap is sometimes decolor- 
ized by animal charcoal, and the evaporated product sold as 
"jalapin." 

Jalap resin is insoluble in oil of turpentine ; common resin, 
or rosin, soluble. If the presence of the latter is suspected, 
the specimen should be powdered, digested in turpentine, the 
mixture filtered, and the filtrate evaporated; no residue, or not 
more than yielded by the turpentine itself, should be obtained. 

Tampico Jalap, from Ipomcea simtdans } yields a resin which appar- 



496 ORGANIC CHEMISTRY. 

ently is chiefly convolvulin, but sometimes contains jalapin : for a 
sample obtained by Hanbury was entirely soluble in ether, and 
another extracted by Umney was almost wholly soluble, while Evans 
purified some, half only of which was soluble. 

The Kaladana resin, or Pharbitisin of India (from Pharbitis Xil. 
P. I.), is a cathartic analogous to, if not identical with, resin of 
jalap. 

Loganin, C 25 H 3i O u , is a glucoside obtained from the pulp of the 
fruit and from the seeds of Strychnos nux-vomica. Loganiacese, by 
Dunstan and Short. Boiled with dilute sulphuric acid, it yields glu- 
cose and loganetin. 

Picrotoxix, U. S. P., is a crystalline bitter poisonous principle 
(Trinpb-, picros. bitter, and to^ikov, toxicon, poison) occurring in Coc- 
culus indicus, the dried fruits of Anamirta cocculas [Anamirta Cani- 
culata, Colebrooke). Ludwig regarded it as a glucoside, but its con- 
stitution is not yet satisfactorily ascertained. Barth and Kretschy 
state that the so-called picrotoxin may be separated into picrotoxin 
proper (C 15 H 16 6 ,H 2 0). which is bitter and poisonous : picrotin 
(C 25 H 30 O 12 4- ?l H 2 O). which is bitter, but not poisonous ; and anamirtin 
(C ]9 H 2i O 10 ), which is neither bitter nor poisonous. Schmidt asserts 
that the original picrotoxin is definite, and has the formula C 30 H 3i - 
13 , but that some solvents decompose it into pi 'crotoxin in, C 15 H ]6 6 , 
which is poisonous, and picrotin. C 15 H 18 T , which is not poisonous. 

Quassix (C 10 H 12 6 S , Wiggers, or C^H^Og, Christensen). obtained 
from Quassio? Lignum, is said to be a glucoside, but Oliveri and 
Denaro question the statement, and find quassia to have the formula 

Salicix (C 13 H ls O T ). — This substance [Salicinum, U. S. P.) is con- 
tained in, and easily extracted from, the bark of willow. Salix Alba 
(Salix, U. S. P.), and of other species of Salix, especially from Scdix 
helix. It occurs in white, shining, bitter crystals, soluble in about 
twenty-eight times its weight of water or sixty-five of spirit at com- 
mon temperatures. 

Tests. — 1. To a small portion of salicin placed on a white 
plate or dish add a drop of strong sulphuric acid ; a deep-red 
color is produced. 

2. Boil salicin with diluted sulphuric acid for some time ; it 
is converted into saligenin or saliyenol (C T H fc 2 ) and glucose. 

C 13 H 18 7 + H 2 = C 6 H 4 (OH)CH 2 + C fi H 12 6 

Salicin. Water. Saligenol. Glucose. 

Examine a portion of the solution for grape-sugar by the cop- 
per test. 

3. To another portion of the liquid, carefully neutralized, 
add a persalt of iron : a purplish-blue color is sometimes pro- 
duced, due to the reaction of the saligenin and the ferric salt. 
The saligenin is, however, so rapidly decomposed by acids into 
salirctin (C 7 H 6 0) and water that this reaction is almost valueless 



GLUCOSIDES. 497 

as a test. Saligenin may readily be obtained by action of synap- 
tase on salicin. 

4. Heat a mixture of about 1 part of salicin, 1 of red chro- 
mate of potassium, 1| of sulphuric acid, and 20 of water in a 
test-tube ; a fragrant characteristic odor is evolved, due to the 
formation of salcylic aldehyde (C 6 H 4 OH.COH), an essential oil 
identical with that existing in meadow-sweet {Spiraea ulmarid) 
and in heliotrope. 

2C 6 H 4 OH.CH 2 OH + 2 == 2C 6 H 4 .OH 4 .COH + 2H 2 

Saligenol. Oxygen. Salicylic Water, 

aldehyde. 

Santonin (C 15 H 18 3 ). — This substance is, apparently, the anhy- 
dride of a weak acid (Hesse) insoluble in ammonia, but forming a 
soluble calcium salt. Indeed, by boiling santonin for twelve hours 
with baryta-water, Cannizarro has obtained a salt from which hydro- 
chloric acid separates sardonic acid (C 15 H 20 O 4 ). Santoninate of 
Sodium (Sodii Santonince, U. S. P.) has the formula 2NaC 15 H 19 4 ,- 
7H 2 0, and occurs in colorless crystals unstable when exposed to 
light. From a solution of santonate of calcium the santonin is pre- 
cipitated by acids. Boiled for some time with diluted sulphuric 
acid, it yields 87 per cent, of an insoluble resinous substance (san- 
toniretin) and glucose (Kosmann). Santonin (Santoninum, U. S. P., 
and Trochischi Sodii Santoninatis, IT. S. P.) is official. It is soluble in 
an aqueous solution of twice its weight of carbonate of sodium. 
Possibly, in constitution, as suggested by Berthelot, santonin resem- 
bles carbolic acid ; in other words, it is a phenol, C 15 H 15 30H. 

Process. — The process for its preparation consists in boiling San- 
tonica, IT. S. P. (the unexpanded flower-heads of Artemisia Mari- 
tima, IT. S. P., or Levant worm-seed), with milk of lime (whereby 
santonate of calcium is formed), straining, precipitating the santonin 
or santonic acid by hydrochloric acid, washing with ammonia to 
remove resin, dissolving in spirit and digesting with animal charcoal 
to get rid of coloring-matter, setting the spirituous solution aside to 
deposit crystals of santonin, and purifying by recrystallization from 
spirit (Mialhe). 

Test. — To highly diluted solution of perchloride of iron add 
an equal bulk of concentrated sulphuric acid. To this reagent 
add the santonin, or powder or substance suspected to be san- 
tonin, and cautiously apply heat. A red, purple, and finally 
violet color is produced (Lindo). Santonin added to warm alco- 
holic solution of potash yields a violet-red color. 

Tanacetic Acid, from the leaves and tops of Tanacetum mlgare, or 
Tansy (Tanacetimi, IT. S. P.), is a yellow crystalline acid having the 
medicinal properties of santonin. 

Saponin (C 32 TI 54 18 , Rochleder, Schiaparelli also) is a peculiar glu- 
coside occurring in Soapwort, the root of the common Pink, and 
many other plants ; its solution in water, even though very dilute, 
42 * 



498 ORGANIC CHEMISTRY. 

froths like a solution of soap. Heated with dilute acids, it yields 
sugar and saponetin, C 40 H 66 O ]5 . Pereira considered smilacin {Sal- 
separin or Parallin) one of the principles of the supposed activity 
of the root of Smilax officinalis, or Sarsaparilla {Sarsaparilla, U. S. 
P.), to be closely allied to, if not identical with, saponin. Accord- 
ing to Klunge {Pharmacographia), parallin, by action of acids, 
yields parigeniii. The aqueous solutions of parallin froth when 
shaken. 

Saponin is also met with in the root of Polygala Senega {Senega, 
U. S. P.), though the active principle of senega is said to reside in 
polygalic acid, probably a glucoside-derivative of saponin. 

Saponin is readily obtained from the bark of Quillaia saponaria 
or soap-bark {Quillaia, U. S. P.) by boiling the aqueous extract in 
alcohol and filtering while hot. Flocks of saponin separate on cool- 
ing. It is a white, non-crystalline, friable powder. The alleged 
toxic properties of commercial saponin are said by Robert to be due 
to sapotoxin and quillaic acid. 

Scammonin (C 84 H 56 16 ). — Boil resin of scammony (Resina 
Scammonii, U. S. P.) with diluted sulphuric acid for some 
time ; glucose may then be detected in the liquid, a resinous 
acid termed scammoniol (C u H 13 3 ?) being produced at the 
same time. 

Natural scammony {Scammonium, U. S. P.) is an exudation from 
incisions in the living root of Convolvulus Scammonia. It contains 
from 10 to 20 per cent, of gum, and therefore when rubbed up with 
water gives an emulsion. " Ether removes about 75 per cent, of 
resin" (B. P.). The official resin of scammony contains no gum, 
and therefore gives no emulsion when rubbed up with water. It is 
made by digesting the root in spirit, adding water, distilling off the 
alcohol, and washing the residual resin with hot water till free from 
gum. There seems to be little or no chemical difference between 
the extracted resin and the resin of the exuded scammony. 

Resin of scammony is soluble in all proportions in ether. Spir- 
gatis states that it is identical with the resin of Mexican Male Jalap, 
which also is soluble in ether. Sulphuric acid slowly reddens it. It 
is said to be liable to adulteration with resin of true jalap, guaiacum 
resin, and common rosin. Resin of true jalap is insoluble in ether; 
guaiacum resin is distinguished by the color-tests mentioned under 
Guaiacix, and rosin by the action of sulphuric acid. 

Scillitin. — Schroff, and afterward Riche and Remont, believed 
the bitter principle of the squill-bulb {Scilla, B. P.) to be a gluco- 
side. Merck has extracted substances which he has termed scilli- 
picxin, scillitoxin, and scillin. Schmiedeberg has given the name 
of sinestrin to a squill principle. But no definite crystalline prin- 
ciple has yet been obtained. Squill contains a large quantity of 
mucilage. 

The bulbous root of Crinum asiaticum is official in the Pharma- 
copoeia of India {Crini Radix, P. I.) as a substitute for squill. It 
has not been chemically investigated. 



IMPERFECTLY EXAMINED SUBSTANCES. 



499 



Strophanthin (C 20 H 34 O 10 ). — According to Frazcr, this is the active 
principle of strophanthus-seed (Strophanthus Kombi), and is a glu- 
coside. He obtained it in crystals. Acids convert it into glucose 
and crystalline strophanthidin. Phosphomolybdic acid produces in 
solutions of strophanthin a bright bluish-green color. Helbing 
states that its aqueous solution yields, with a trace of solution of 
perchloride of iron and a little sulphuric acid, a reddish-brown pre- 
cipitate which after an hour or two turns green. Sulphuric acid 
colors strophanthin dark green, changing to reddish brown. Recent 
researches indicate that strophanthin is only one of the active prin- 
ciples of the different varieties of strophanthus. 



QUESTIONS AND EXERCISES. 

803. Define glucosides, and mention those of pharmaceutical 
interest. 

804. Draw out an equation illustrative of the development of oil 
of bitter almonds. 

805. How much pure amygdalin will yield one grain of real 
hydrocyanic acid? 

806. To what does cherry-laurel water owe activity ? 

807. Mention the active principle of senna. 

808. By what process is the glucoside of the purple foxglove 
prepared ? 

809. State the circumstances under which guiaicum resin and 
jalap resin yield glucose. 

810. Mention a test for guaiacum resin. 

811. How may the adulteration of jalap resin by rosin be detected ? 

812. Enumerate the tests for salicin. 

813. How is santonin officially prepared? 

814. Name sources of saponin. 

81.5. What is the difference between scammony and resin of 
scammony ? 

816. How would you detect resins of turpentine, guaiacum, or 
jalap in resin of scammony? 



BITTER OR TONIC SUBSTANCES, ETC. 

The following articles, employed medicinally in such forms as decoc- 
tion, extract, infusion, tincture, etc., contain active principles which 
have not yet been thoroughly examined. Some of these principles 
have been isolated, and a few have been obtained in the crystalline 
condition ; but their constitution has not been sufficiently well made 
out to admit of the classification of the bodies either among alkaloids, 
glucosides, acids, or other well-marked principles : — 



Andrographis Caules et Radix, 
P. I., from Andrographis pa- 
niculafa Kariyat. 

Anthem id is jiores. 



Apocynvm. Canadian hemp. 
Asclepias tuberosa. Pleurisy-root 

(Asclepedin). 
Aurantii cortex (Hesperidin), 



500 



ORGANIC CHEMISTRY. 



Azadirachtce Cortex et Folia, P. 
I., from Azadirachta indica, 
Nim or Margosa. (A resin ; 
C 36 H 50 O n . Broughton.) 

Bonducella semina, P. I., from 
Ccesalpinia (guilandina) bon- 
ducella. Bonduc-seeds or nick- 
ar-nuts. 

Buchu folia. 

Calendula officinalis. Marigold. 
(Calendulin, Stoltze.) 

Calotropis Cortex, P. I., from Ca- 
lotropis procera and C. gigantea. 
Mudar. 

Canellce cortex (Cascarillin, 
C 12 H n 4 ). 

Caulophyllum ilialictroides. Blue 
cohosh. Alkaloid ? 

Cimicifuga {Aetata) racemosa 
(Oimicifugin ; said by Con- 
ard to be neutral, and by 
Falck alkaloidal). Black 
snake-root {Cimicifugoz Rhi- . 
zoma, B. P.). 

Cypripedium pubescens (Cypripe- : 
din?). Ladies' Slipper. 

Euonymus atropurpureus. Wa- 
hoo-bark (Euonymin ?). 

Eupatorium perfoliatum. Thor- 
ough wort or Boneset. 

Gulancha (Tinosporce Radix et 
Caules, P. I.). 

Gynocardice semina, from Gyno- 
cardia odorata (Chauhnugra, 
P. I.). 

Hamamelis virginica. Witch- 
hazel. 



Hydrocotyles folia, P. I., from 
Hydrocotyle asiatica. Indian 
pennywort. 

Iris versicolor. Blue flag (Iridin 
or Irisin ?). 

Lactuca (Lactucin, etc.). The 
milk-juice, dried, yields Lactu- 
carium, U. S. P. 

Lappa, U. S. P., Arctium lappa, 
Lappa officinalis. Burdock. 

Lupulus. 

Magnolia. Swamp Sassafras or 
Beaver Tree. 

Marrubium. Ilorehound. Mar- 
rubein, a crystalline bitter 
substance (Mein). 

Medico? folia. Matico. 

Melia Azedarach (Resin, Jacobs). 

Pepo. The seed of Cucurbita pepo. 
A remedy for tape- worm. 

Phytolacca Bacca et Radix. Poke- 
berry and root. Phytolaccin, 
a crystalline substance (Claas- 
sen). 

Scutellaria. Skullcap. 

Serpentaria. Virginia Snakeroot. 

Soymidoi Cortex, P. I. Rohun- 
bark, from Soymida febrifuga. 

Taraxaci radix (Taraxacin). 

Toddalim radix, P. I. 

Triticum repens. Rhizome of 
couch-grass. 

Veronica virginica, or Leptandra 
virginica. Culvers-root ; Lep- 
tandra, U. S. P. (Leptandrin ?). 

Viburnum. Black haw ( Vibur- 
nin). 



ALKALOIDS. 

Constitution of Alkaloids or Organic 

Natural Alkaloids. — The natural organic bases, alkaloids, or 
alkali-like bodies (ridoc, eidos, likeness), have many analogies 
with ammonia. Their constitution, as a class, is not yet satis- 
factorily known ; but some are probably direct derivatives of a 
single molecule of ammonia (NH 3 ) or of double, triple, or quad- 
ruple molecules (N 2 H 6 , N 3 H 9 , N 4 H 12 ) ; others of ammonias in which 
the ammoniacal structure is largely merged in or conditioned by a 
benzenoid or aromatic structure, or, vice versa, in which the ben- 



ALKALOIDS. 501 

zenoid character is conditioned by the ammoniacal ; while others, 
again, certainly appear to be benzenoid, but of a more or less 
nitrogen-benzene (pyridinoid) rather than a completely carbon- 
benzene character — benzene (p. 634) in which CI1 /// is displaced 
by N T/// . 

Artificial Alkaloids. — Numerous artificial alkaloids or artificial 
organic bases having a simple ammoniacal constitution have already 
been formed. These are sometimes termed amines, and are pri- 
mary, secondary, and tertiary according as one, two, or three atoms 
of hydrogen in ammonia have been displaced by radicals, as seen 
in the following general formulae (R = any univalent radical) : — 



R) R) 

II [ N R I N 
II J II J 


R) 

RlN; 
Rj 


le following examples : — 




C 2 H 5 ) C 2 II 5 ) 
II N 0,115 N 
II j H J 


C 2 II 5 [ N. 
C 2 H 5 J 


Ethylamine or Diethylamine or 
ethylia (C 2 H 7 N). diethylia (C 4 H U N). 


Triethylamine or 
triethylia (C 6 H 15 N). 



The three classes have also been termed amidogen-bases (NH 2 ), 
imidogen-bases (Nil), and nitrile-bases (N). 

Mode of Formation of Artificial Ammoniacal Alkaloids. — A few 
illustrations will suffice. Just as the addition of iodide of hydrogen 
(HI) to ammonia (that is, the common trihydrogen ammonia, NII 3 ) 
gives iodide of common ammonium (NIIIIIIIII or NH 4 I), so the 
addition of iodide of ethyl (C 2 H 5 I or EtI) (see page 401) to ammo- 
nia (NII 3 ) gives the iodide of ethyl-ammonium (NHHHEtl, or 
NH 3 EtI, or NII 3 C 2 II 5 I). A fixed alkali turns out common ammo- 
nia (NIIIIII) from the iodide (or any other salt) of common ammo- 
nium ; it turns out ethyl-ammonia (NIIHEt) from the iodide (or any 
other salt) of ethyl-ammonium. Ethyl-ammonia (or ethylia or ethyl- 
amine), NIIIIEt, with iodide of ethyl, EtI, gives iodide of diethyl- 
ammonium [NHIIEtEtl, or NH 2 Et 2 I, or NH 2 (C 2 II 5 ) 2 I]. From the 
latter, potash turns out diethyl-ammonia (NHEt 2 ). Diethyl-ammo- 
nia (diethylia or diethylamine) with iodide of ethyl gives iodide of 
triethyl-ammonium (NHEt 3 I). The latter with alkali gives triethyl- 
ammonia or triethylia or triethylamine (NEt 3 ), and this with iodide 
of ethyl gives iodide of tetrethyl-ammonium, NEt 4 I. 

What has just been stated respecting iodide of ethyl is true of 
other salts of ethyl ; and what is true of salts of ethyl is true of 
salts of an immense number of other radicals — univalent, bivalent, 
etc. ; so that a vast number of artificial ammoniacal alkaloids and 
their salts can be produced. The reactions are not always so sharp 
as those just given. Mixtures of primary, secondary, ami tertiary 
compounds rather than either alone often result in an experiment: 
but the reactions are typically true. 

Some of these artificial ammoniacal alkaloids not only resemble 



502 ORGANIC CHEMISTRY. 

natural alkaloids, but are strong caustic liquids, like solution of 
ammonia. 

Then, the displacing radical in an artificial alkaloid or its salt 
may not only be of one kind, as indicated in the preceding para- 
graphs, but of different kinds ; and while the radical displacing one 
atom of hydrogen is keeping its place, any of the many known radicals 
may occupy the position of one or all of the other atoms of hydro- 
gen. Thus, for example, we have methyl-ethyl-amylamine (C 8 H 19 N, 
or NCH 3 C 2 H 5 C 5 H n , or NMeEtAy), a colorless, oily body of agree- 
able aromatic odor. The empirical formulae of the vegeto-alka- 
loids morphine, quinine, etc. may some day be similarly resolv- 
able into rational formulae, either simply ammoniacal, benze- 
noid, or pyridinoid. Their artificial production will then quickly 
follow. 

Methylamine, (CH 3 HHN), and trimethylamine, (CH 3 ) 3 N, are arti- 
ficial ammoniacal alkaloids. The former was found, by Schmidt, in 
Mercurialis annua and M. perennis, and previously by Reichardt, 
who termed it mercurialine. Trimethylamine is also produced in 
large quantities in the dry distillation of the evaporated residue of 
the spent wash produced in beet-root spirit distilleries. 

Propylamine or tritylia (C 3 H 7 HHN) is a volatile oil, one product 
of the destructive distillation of bones and other animal matters. 

The organic bases derived from one molecule of ammonia are 
termed monamines ; from two molecules, diamines; from three, 
tr i amines ; and from four, tetr amines : — 

R) R 2 ) R 3 ) R 4 ) 

rIn rJn 2 r"Jn 3 rJn 4 

Rj R 2 J R 3 ) * Rj 

In these amines any bivalent, trivalent, or quadrivalent radical 
may occupy the place of two, three, or four univalent 
radicals. 

Wurtz first obtained methylamine and ethylamine in 1849 ; Hof- 
mann, in 1850 and subsequently, added enormously to our know- 
ledge of the secondary, tertiary, and other amines, and to the 
directly ammoniacal type of bodies generally. Kekule linked on 
the aromatic or benzenoid type in 1865. Dewar and Korner, almost 
simultaneously in 1870, demonstrated the benzenoid character of 
pyridine and quinoline (see next paragraph), while no one has since 
been so active in alkaloidal research as Ladenburg. 

Vegetal Alkaloids. — These are of great importance to the medical 
and pharmaceutical student. They are treated in considerable detail 
in the succeeding pages. 

Animal Alkaloids. — Many well-known alkaloids occur in the juice 
of the flesh and in other parts of animals. Ordinary extract of meat 
contains abundance of crystals of creatine, C 4 H 9 N 3 0. 2 , and some crea- 
tinine. C 4 H 7 N 3 0. Creatine easily parts with the elements of water 
and yields creatinine ; it takes up the elements of water and yields 
sarkosine, C 3 H 7 N0 2 , and urea, CH 4 N 2 0. Sarkosine is methyl-gly- 
cocoll. Taurine, C 2 H 7 NS0 3 , may be obtained from bile, and it can 



ALKALOIDS. 503 

be constructed artificially from its elements. Glandular tissue, as 
of the spleen, brain, and pancreas, yield, as a product of work, 
leucine, C 6 H 13 N0 2 , which occurs in white, pearly crystals. Gautier 
recently obtained several new alkaloids from albuminoids, and 
hence termed them leucomaines (levnoua, leucoma, white of egg) — 
namely, xanthocreatinine, C 5 H 10 N 4 O ; crusocreatinine, C 5 H 8 N 4 ; 
amphicreatine, C 9 H ]9 N 7 4 ; and pseudoxanthine, C 4 H 5 N 5 0. The 
leucomaines and the animal alkaloids generally are of great physi- 
ological interest. Some of the leucomaines are toxic, and indis- 
tinguishable from ptomaines 5 in fact, the three classes merge into 
one another. 

Ptomaines. — A series of diamines, many of them toxic, have been 
isolated by Brieger from decaying nitrogenous animal principles, 
including the putrid proteids or albuminoids of the human body 
itself; hence the name ptomaines (nrcojua, ptoma, a corpse). These 
have some medico-legal importance, but, inasmuch as they may 
occur in life, poisoning the blood during the progress of dis- 
ease — especially disease associated with the development of micro- 
organisms or microbes ; that is, zymotic disease {Cvuq, zume, fer- 
ment) — they have great pathological interest ; indeed, physiological 
importance also, for one of a curaroid character seems to play a part 
in the process of digestion. The names of some of these base?* are 
neurine (C 5 H ]3 NO) and neuridine (C 5 H 14 N 2 ), from putrid flesh ; mus- 
carine (C 5 H 13 N0 2 ) and gadinine (C 7 H 16 N0 2 ), from putrid fish ; cadav- 
erine (C 5 H 16 N 2 ), saprine, and putrescine (C 4 H 12 N 2 ), from putrid human 
remains, choline being met with in the earlier stages of decay ; and 
tetanine, C ]3 H 30 N 2 O 4 , the administration of which to animals pro- 
duced symptoms resembling those of tetanus in man from beef 
putrefied by the agency of the microbe, which is associated with 
the cause of traumatic tetanus so distressing to the human subject. 
Tyrotoxicon was the name given by Vaughan to a toxic ptomaine he 
isolated from poisonous cheese (rvpbr, twos, cheese ; ro^uwv, toxicon, 
poison), afterward from poisonous milk and cream, which, taken as 
food, had caused more or less vomiting, headache, and diarrhoea. 
He afterward recognized it as diasobenzene, C 6 H 5 .N : N.OH. Brieger 
states that when shellfish is poisonous it is due to the presence of a 
ptomaine, mytiloxine, C 6 H 15 N0 2 . Para- and meta-phenylene diamine 
appear to have all the characters of leucomaines or ptomaines, the 
latter causing intense influenza. 

Evidence of Constitution of the Natural Alkaloids. — Attempts to 
form artificially the natural organic bases commonly used in med- 
icine have hitherto failed. Many artificial colorific alkaloids of the 
type of amido-benzene (aniline or phenylamine) and of a curious 
double nitrogen (azo- or diazo-) type (see the non-colorific diazoben- 
zene above) have been obtained. But the type of the natural medi- 
cinal alkaloids seems rather to be found in pyridine^ C 6 H 5 N. Pyri- 
dine is producible in various ways, but was originally obtained from 
bone-oil (a product of the destructive distillation of bones), together 
with the homologues picoline, C*H.,N (or methyl-pyridine, ortho-, 
meta-, or para-)-, lutidine, C 7 H 9 N ; and collidine, U 8 H n N, forming 
an homologous series of pyridine bases, C n H 2n . 6 N. 



504 THE ALKALOIDS. 



N 



C fi H\ HC C.NH, HC CH 

I II I II 

HC g HC CH 

V 

H H 

Phenylaniine or Amidobenzene. Pyridine. 

From quinine, cinchonine, and strychnine, by the disruptive action 
of caustic alkalies, not only pyridine and homologues, but quinoline 
or chinoline, C 9 H 7 N, have been obtained ; hence pyridine and quino- 
line would seem to contribute to the construction of those and sim- 
ilar alkaloids. Quinoline can be made in various other ways, espe- 
cially (Skraup) from nitrobenzene, aniline, and glycerin. Quinoline 
is closely related both to benzene and to pyridine, as will be seen by a 
glance at the following formula. Its relation to naphthalene (two 
carbon-conjoined benzene residues) is just the relation of pyridine 
to benzene : — 

H H H 

HC C CH HC C CH 

I II I I II I 

HC C CH HC C CH 



c c c c 

II H II H 

Naphthalene. Quinoline. 

Both pyridine and quinoline form additive compounds with hydrogen. 
(See " Piperidine " in Index.) Chemists, in the hope, doubtless, of dis- 
covering how to produce the medicinal alkaloids artificially, have 
obtained several alkaloidal derivatives of quinoline. One, kairine, 
somewhat resembles quinine. Again, alkaloids yield organic acids, 
and organic acids, notably those occurring in nicotine-yielding and 
morphine-yielding plants, may be converted into pyridine compounds 
when the constituents of their molecules are interwoven with those 
of ammonia. 

A careful consideration of the above and allied facts irresistibly 
leads to the inference that we are at last almost " within measurable 
distance" of the artificial production of most of the natural alka- 
loids — a subject still of financial and general commercial weight, of 
considerable technological (including pharmaceutical) importance, 
of very great medical consequence, especially taken in connection 
with its ramifications, and of transcendent interest as illustrating 
the working of the forces of nature within the molecules of matter. 

Animal and Vegeto-animal Alkaloids. — Choline, C 5 H 15 N0 2 , occurs 
in the bile and the brain, also in ergot and ipecacuanha, etc. Gua- 
nine, C 3 H 5 N 5 0, and Sarkine, C 5 H 4 N 4 0, are found in flesh and in 



f H 


f H 


N^H 


1NNH 


(H 


(OH 


Ammonia. 


Hydroxyl- 




amine. 



MOKPHINE. 505 

young plane-leaves. Fresh meat furnishes Carnine, C 7 H 8 N 4 3 , Cruso- 
creatinine, C 5 H 8 N 4 0, and Xantho-creatinine 1 C 5 H 10 N 4 O. Urine yields 
Creatinine, CJI 7 N 3 0. Betaine, C 5 H n N0 2 , is met with in beet-root 
and in urine. 

Hydroxylamine. — Besides the amide, imide, and nitrile bases 
already mentioned, ammonia may have one atom of its hydrogen 
displaced by hydroxyl, hydroxylamine (NH 2 OH) resulting. It is 
often formed when nascent hydrogen acts on an oxide of nitrogen, 
as when zinc, diluted sulphuric acid, and a little nitric acid are 
brought together. It yields substitution-products, as ethyl-hydroxyl- 
amine (NTIC 2 H 5 OII), and additive compounds, as hydrochlorate of 
hydroxylamine (NH 2 OH,HCl) :— 

(C 2 H 5 fH 

N \ II N \ II I-1C1 

(OH (OH 

Ethyl Hydrochlorate of 

hydroxylamine. hydroxylamine. 

Note on Nomenclature of Natural Alkaloids. — The first syllables 
of the names of the natural alkaloids recall the name of the plant 
whence they were obtained or some characteristic property. It is to 
be regretted that the last syllable is not either ine or ia, instead of 
sometimes one and sometimes the other. The termination in ia dis- 
tinguishes the alkaloids from some other substances the names of 
which end in ine, as chlorine, bromine, iodine, fluorine, etc., but 
traders generally, and the compilers of the American, British, 
French, and German Pharmacopoeias, adopt the termination in 
ine. The names of the salts of the alkaloids are given on the 
assumption that the acid unites with the alkaloid without decom- 
position. Thus, hydrochlorate (sometimes termed " hydrochloride") 
of morphine is regarded as morphine with added hydrochloric acid, 
as we might assume sal-ammoniac to be ammonia (NH 3 ) with hydro- 
chloric acid (HC1), and name it hydrochlorate of ammonia (NH 3 HC1), 
instead of chloride of ammonium (NH 4 C1). All acids, even sulphy- 
dric, unite with alkaloids and form salts having similar names. 

Antidotes. — In cases of poisoning by alkaloids, emetics and the 
stomach-pump must be relied on rather than chemical agents. But 
astringent liquids may be administered, for tannic acid precipitates 
many of the alkaloids from their aqueous solution, absorption of the 
poison being thus possibly retarded. 



MORPHINE, OR MORPHIA. 

Formula C n II 19 N0 3 ,II 2 0. Molecular weight 303. 

Occurrence. — Morphine occurs in opium (the inspissated juice of 
the fruit Papaveris capsulce, of the White Poppy, Vapavw somnif- 
erwm) as meconate of morphine [(C 17 H 19 N0 3 ) 2 , C 7 H 4 7 , 5H 8 0, Dott, 

and as sulphate]. The dried poppy-capsule of pharmacy "contains 
opium principles, but varying much in nature and proportion. The 
presence in the capsule of morphine, narcotine, and meconic acid 



506 THE ALKALOIDS. 

has been demonstrated, and, by Groves, of narceine and codeine. 
Ordinary Asia Minor opium {Opium, U. S. P.) (Turkey, Smyrna, or 
Constantinople opium) should contain "not less than 9 per cent, of 
morphine," and when dried at 85° C. and powdered (Opii Pulvis, 
U. S. P.), from 12 to 16 per cent, of morphine. 

Denarcotized Opium (Opium Denarcotisatum, U. S. P.) is dried 
and powdered opium from which narcotine has been washed out by 
ten times its weight of stronger ether, the product being redried at 
85° C, and made up to its original weight with powdered sugar of 
milk. 

Morphina, U. S. P., may be made by adding to infusion of opium 
an equal bulk of alcohol, then slight excess of ammonia, and setting 
aside for crystalline morphine to separate. It is purified by recrys- 
tallization. 

Process for Hydroclilorate. — The hydrochlorate, C 17 H ]9 N0 3 ,HC1,- 
3H 2 (Morphine? Hydrochloras, U. S. P.), occurs in slender white 
acicular crystals. It is prepared by simply decomposing an aqueous 
infusion of opium with chloride of calcium, meconate of calcium and 
hydrochlorate of morphine being produced. (If the infusion, which 
is always acid, be first nearly neutralized by the cautious addition of 
small quantities of very dilute solution of ammonia, the chloride 
of calcium then at once causes a precipitate of meconate of calcium, 
which can be filtered off, leaving a colored solution of hydrochlorate 
of morphine. On the large scale (vide B. P.) the details are some- 
what different.) The salt is partially purified by crystallization 
from the evaporated liquid, then by treatment of the solution of 
the impure hydrochlorate by animal charcoal, and lastly, by pre- 
cipitation of the morphine from the still colored liquid by ammonia 
and re-solution of the morphine in hot dilute hydrochloric acid 5 
hydrochlorate of morphine separates out on cooling. 

Hydrochlorate of morphine deposited from a hot solution in about 
twenty times its weight of alcohol is anhydrous. 

Morphine may also, of course, be prepared by the methods given 
for its quantitative separation from opium (see Index). 

Morphines Sulphas, U. S. P. (2C 17 H 19 N0 3 ,H 2 S0 4 ,5H 2 0) may be 
made by neutralizing morphine with sulphuric acid. It is a con- 
stituent of Pulvis Morphince Compositus. 

Process for Acetate. — Acetate of morphine (C 17 H 19 N0 3 ,C 2 H 4 2 ) 
(Morphince Acetas, U. S. P.) is a white pulverulent salt prepared by 
dissolving pure morphine in acetic acid. One grain of acetate, so 
made, in twelve minims of water, forms the Injectio Morphice Hypo- 
dermica, B. P. 

Both the hydrochlorate and acetate of morphine are soluble in 
water, but the solution is not stable unless acidulated and containing 
alcohol ; hence the official solutions, 4 grains in one ounce, 1 in 110 
(Liquor Morphice Hydrochloratis, B. P., and Liquor Morphice Acetatis, 
B. P.), consist of three parts water and one part rectified spirit, a 
few minims per ounce of hydrochloric or acetic acid being added. 
Even solid acetate of morphine is unstable, slowly dissociating into 
acetic acid and morphine ; hence the acid odor of acetate of mor- 
phine. 



MORPHINE. 507 

Solubility of morphine salts in water at 60° F. — According to 
Dott, 1 part of the respective salts is soluble in the annexed number 
of parts of water : Acetate, 2\ ; Tartrate, 9f ; Sulphate, 23 ; Hydro- 
chlorate, 24 •, Meconate, 34. 

Tartrate of Morphia has the formula (C n H 19 N0 3 ) 2 , C 4 II 6 6 ,3H 2 0. 

Other alkaloids exist in opium. In the above process a consider- 
able quantity of an alkaloid of very weak basic properties, narcotine 
(C 22 H 23 N0 7 ) (Narcotina, P. I.), remains in the exhausted opium, and 
may be extracted by digesting in acetic acid, filtering, precipitating 
by ammonia. It crystallizes in brilliant needles from alcohol or 
ether. By oxidation it yields cotarnine and an acid termed opianic. 

Codeine (C 18 H 21 N0 3 ,H 2 0) (Codeina, U. S. P.) is soluble in the slight 
excess of ammonia employed in precipitating the morphine. " Codeine 
is dissolved by sulphuric acid containing 1 per cent, of molybdate 
of sodium to a liquid having, at first, a dirty-green color, which, after 
a while, becomes pure blue, and gradually fades, within a few hours, 
to pale yellow. On dissolving codeine in sulphuric acid a colorless 
liquid results, which, on the addition of a trace of ferric chloride 
and gentle warming, becomes deep blue. An aqueous solution of 
codeine, added to test-solution of mercuric chloride, should produce 
no precipitate ; and if codeine be added to nitric acid of sp. gr. 1 .200, 
it will dissolve to a yellow liquid which should not become red (differ- 
ence from and abs. of morphine)." — U. S. P. It reduces a solution 
of 1 part of selenite of ammonium in 20 of strong sulphuric acid, 
yielding a green color (Lafon). From the mother-liquors there have 
also been obtained thebaine (C 19 H 21 N0 3 ), papaverine (C 21 H 21 N0 4 , 
Hesse ; C 20 H 21 NO 4 , Merck), opianine (C 21 H 21 N0 7 ?), narceine (C 23 H 29 - 
N0 9 ), cryptopine (C 21 H 23 N0 5 ), meconine (C ]0 H 10 O), meconoisine (C 8 - 
H 10 O 2 ),- laudanine (C 20 H 23 NO 4 ), codamine (C 20 II 25 NO 4 ), gnoscopine 
(C 34 H 36 N 2 O n ), pseudomorphine (C 17 H 18 N0 3 ), protopine (C 20 H 19 ]S ^0 5 ), 
laudanosine (C 21 H 2t N0 4 ), hydrocotarnine (C 12 H ]5 N0 3 ), rhceadine (C 20 - 
H 21 N0 6 ), meconidine (C 21 H 23 N0 4 ), lanthopine (C 23 H 25 N0 4 ). A little 
acetic acid also exists in all opium (D. Brown). 

Analytical Reactions. 

First Analytical Reaction. — To a minute fragment of a salt 
of morphine add one drop of water, and warm the mixture until 
the salt dissolves, then stir the liquid with a glass rod moist- 
ened by a strong neutral solution of perchloricle of iron ; a 
dirty-blue color is produced. This effect is not observed in 
dilute solutions. The reaction is accompanied by a reduction 
of the ferric salt to ferrous. The occurrence of the latter may 
be shown by ferricyanide of potassium giving Turnbull's blue. 

Second Analytical Reaction. — To a drop or two of a strong 
solution of a morphine salt in a test-tube add a minute fragment 
of iodic acid (H10 3 ; page 295) ; iodine is set free. Into the 
upper part of the tube insert a glass rod covered with mucilage 
of starch, and warm the solution ; dark-blue starch iodide is 



508 THE ALKALOIDS. 

produced. If the mixture of morphine and iodic acid be shaken 
up with chloroform or bisulphide of carbon, a violet solution is 
obtained. 

This reaction is only confirmatory of others, as albuminous matters 
also reduce iodic acid. 

Third Analytical Reaction. — To a few drops of an aqueous 
infusion of opium add a drop of neutral solution of perchloride 
of iron ; a red solution of meconate of iron is produced. Add 
solution of corrosive sublimate ; the color is not destroyed 
(as it is in the case of sulphocyanate of iron, a salt of similar 
tint). 

In cases of poisoning by a preparation of opium this test is almost 
as conclusive as a direct reaction of morphine (the poison itself), 
meconic acid being obtainable from opium only. 

Other Reactions. — Add carbonate of sodium to a solution of 
a salt of morphine ; a white precipitate of morphine falls, 
slowly, and of a crystalline character if the solution is dilute. 
Collect this precipitate, and moisten it with neutral solution of 
perchloride of iron ; the bluish tint above referred to is pro- 
duced. Add an alkali to a solution of hydrochlorate or acetate 

of the alkaloid ; morphine is precipitated, soluble in excess of 

the fixed alkali ; far less readily so in ammonia. Moisten a 

particle of a morphine salt with nitric acid ; an orange-red col- 
oration is produced. Warm a little morphia with strong sul- 
phuric acid and arseniate of sodium ; blue-green tinges result. 

To morphine add strong sulphuric acid, mix, and strew 

nitrate of bismuth on the fluid ; the mixture turns dark brown 

or black. Heat morphine on platinum foil ; it burns 

entirely away. 

Apomorphine (C n H 17 N0 2 ). 

Apomorphine (arco, apo, from, and morphine) is an alkaloid obtained 
from morphine by Matthiessen and Wright. It possesses remarkable 
physiological effects : one-tenth of a grain (in aqueous solution) in- 
jected under the skin, or one-quarter of a grain taken into the 
stomach, is said to produce vomiting in from four to ten minutes. 

Process. — Hydrochlorate of morphine is hermetically sealed in a 
thick tube with considerable excess of hydrochloric acid, and 
heated to nearly 300° F. for two or three hours. The product is 
purified by diluting the contents of the tube with water, precipitat- 
ing with bicarbonate of sodium, and treating the precipitate with 
ether or chloroform. On shaking up the ethereal or chloroform solu- 
tion with a very small quantity of strong hydrochloric acid, the sides 
of the vessel become covered with crystals of the hydrochlorate of the 
new base. These may be drained from the mother-liquor, washed 



MORPHINE. 509 

with a little cold water, in which the salt is sparingly soluble, recrys- 
tallized from hot water, and dried on bibulous paper or over sulphuric 
acid. The formula (C, 7 H 17 N0 2 ,HC1) indicates that the new alkaloid 
is derived from morphine by abstraction of the elements of water. 

Hydrochlorate of Apomorphine (Apomorphince Hydrochloras, U. S. 
P.) occurs in "colorless or grayish-white, shining crystals, turning 
greenish on exposure to light and air, odorless, having a bitter taste 
and a neutral or faintly acid reaction. Soluble in 6.8 parts of water 
and in 50 parts of alcohol at 15° C. (59° F.) ; slowly decomposed by 
boiling water or boiling alcohol ; almost insoluble in ether or chloro- 
form ; should it impart color to either of these liquids it should be 
rejected, or it may be purified by thoroughly agitating it with either 
liquid, filtering, and then rapidly drying the salt on bibulous paper 
in a dark place. The aqueous solution, on gentle warming, rapidly 
turns green, but retains a neutral reaction. Solution of bicarbonate 
of sodium, added to an aqueous solution of the salt, throws down the 
white, amorphous alkaloid, which soon turns green on exposure to air, 
and forms a bluish-green solution with alcohol, a purple one with 
ether or pure benzol, and a violet or blue one with chloroform." 

Codeine also, according to the same chemists, yields apomorphine 
by similar treatment, a reaction that would seem to indicate that 
codeine is a methyl-morphine; indeed, Grimaux (Hesse also) has 
since obtained codeine — or, possibly, an isomer of codeine, methyl- 
morphine — from morphine. 

C 17 H 17 CH 3 HN0 3 + IIC1 = CH 3 C1 + H 2 + C 17 H 17 N0 2 

Codeine. Chi. of methyl. Apomorphine. 

Dr. C. R. A. Wright has recently obtained several new derivatives 
of codeine. 

Codeine neither gives a blue odor with ferric chloride nor a red with 
nitric acid. Both codeine and morphine, when heated with a mixture 
of strong sulphuric acid and arseniate of sodium, give a blue color, 
the morphine yielding a greenish-blue and the codeine a violet-blue. 

Constitution of the Opium Alkaloids. — The opium alkaloids, like 
the cinchona alkaloids, have been attacked by many highly skilled 
chemists in the hope that analytical, or, in a sense, destructive, inves- 
tigation would lead to synthetical or constructive knowledge 5 and 
many interesting and promising results have been obtained. But 
the subject is not yet sufficiently advanced for presentation before 
the younger students of medicine or pharmacy. 



QUESTIONS AND EXERCISES. 

817. Write some general formula? of artificial alkaloids. 

818. Name the substances represented by the following formulae : — - 

N. 



C 3 II 7 


\ 


<-W 


\ 


CH, 


H 


N, 


c,u 7 


N, 


Cli; 


U 


[ 


11 


1 


o;ir„ 


cn :! 




CH a 


) 


(Ml, 


11 


( N ' 


C1L 


N, 


on; 


11 




II 




CH, 



510 THE ALKALOIDS. 

819. What is the assumed constitution of the salts of the alkaloids? 

820. Describe the treatment in cases of poisoning by alkaloids. 

821. Give the process for the preparation of Ilydrochlorate of 
Morphine. In what form does morphine occur in opium? 

822. How is Acetate of Morphine prepared? 

823. What plan is adopted for preventing the decomposition of 
the official solutions of morphine? 

824. Mention the analytical reactions of morphine. 

825. In addition to the reactions of morphine, what test may be 
employed in searching for opium in a liquid or semifluid material ? 

826. How is Apomorphine prepared, and what are its properties? 

827. Describe the relation of morphine to codeine. 



QUININE, OR QTJINIA. 

Formula C 20 II^N 2 O 2 ,3II 2 O. Molecular weight 378. 

Source. — Quinine (Quiniha, U. S. P.) and other similar alkaloids 
exist in cinchona-bark as kinates. In the yellow bark (Cinchona 
Flava, U. S. P., from Cinchona cedisaya) chiefly quinine is present ; 
in the pale bark {Cinchonce Pall idee Cortex, B. P., chiefly from C. 
officinalis) other alkaloids are more frequently found ; in the^red bark 
(Cinchona Rubra, U. S. P.) these alkaloids occur in irregular propor- 
tions ; they occur also in various species of Remijia, the cuprea barks. 

Under Cinchona the United States Pharmacopoeia recognizes " the 
bark of any species of Cinchona containing at least 3 per cent, of 
its peculiar alkaloids.'" 

Extraction of the Mixed Alkcdoids. — Take 750 grains of finely 
powdered bark. Make it into a paste with milk of lime (slaked 
lime about 400 grains and water about 4 ounces). Dry the mixture 
over a water-bath. Powder the residue and place the whole in a 
cylindrical percolator. Pour in 3f fluidounces of chloroform. When, 
after standing, packing is complete, allow percolation to commence 
and to proceed slowly. After a time pour 3f fluidounces more chloro- 
form into the percolator. When percolation has ceased transfer the 
percolate to a retort, and add nearly half an ounce of water and 
enough dilute sulphuric acid to make the mixture acid to test-paper. 
Recover the chloroform by distilling from a water-bath, and allow 
the residue to cool ; filter. To the filtrate, which contains the alka- 
loids as acid sulphates, add ammonia in slight excess. Collect the 
precipitated alkaloids on a filter, wash, and dry in the air or over a 
dish of sulphuric acid covered by a bell-jar. (For the separation of 
alkaloids see Index, " Dr. Yrij's process,"" an operation which should 
not be attempted at this stage of study.) 

Process for Sulphate. — Sulphate of quinine (Quininee Sulphas, 
U. S. P.) may be prepared by treating the yellow bark with dilute 
hydrochloric acid, precipitating the resulting solution of hydro- 
chlorate of quinine by soda, and redissolving the precipitated quinine 
in the proper proportion of hot dilute sulphuric acid. This, the com- 
mon commercial sulphate, crystallizes out on cooling in silky acicular 
crystals, one molecule containing two atoms of quinine (2C 20 II 24 N 2 O 2 ), 



QUININE. 511 

one of sulphuric acid (H 2 S0 4 ) and seven of water of crystallization 
(7H 2 0). 

In the process of the former United States Pharmacopoeia 
(1870) lime was used instead of soda, the precipitated quinine 
dissolved in boiling alcohol, the latter recovered by distillation, 
the residual quinine neutralized by diluted sulphuric acid, the 
solution treated with animal charcoal, filtered while hot, set 
aside to crystallize, and recrystallized if necessary. 

Sulphate of quinine, the common or so-called disulphate (C 20 H 24 N 2 - 
2 ) 2 ,H 2 S0 4 ,8H 2 0, is only slightly soluble in water •, on the addition 
of dilute sulphuric acid the so-called neutral sulphate, or soluble 
sulphate {Quinince Bisulphas, U. S. P. ; C 20 H 24 N 2 O 2 ,H 2 SO 4 ,7II 2 O), is 
formed, which is freely soluble. The latter salt may be obtained in 
large rectangular prisms .* An acid sulphate (C 20 H 24 N 2 O 2 ,2H 2 3O 4 ,- 
7II 2 0) also exists. 

The ordinary disulphate of quinine is more soluble in alcohol or 
alcoholic liquids than in water. The citrate of iron and quinine 
(Ferri et Quinince Citras, U. S. P.) is the well-known scale com- 
pound. It is made by dissolving ferric hydrate, prepared from 
ferric sulphate, and quinine, prepared from the sulphate, in solution 
of citric acid ; the liquid, evaporated to a syrupy consistence and 
dried in thin layers on glass plates, yields the usual greenish-yellow 
scales {vide p. 152). 

Quinince Valerianas, U. S. P., may be made by dissolving precipi- 
tated quinine in warm aqueous solution of valerianic acid and setting 
aside to crystallize. Its formula is C 20 H 24 N 2 O 2 ,C 5 H 10 O 2 ,H 2 O. 

Basic Citrate of Quinine has the formula (C 20 IJ 24 N 2 O 2 ) 2 , 1I 3 C 6 TI 5 7 ,- 
5H 2 0. Other citrates contain three molecules of quinine to two of 
citric acid, and one of quinine to one of citric acid. 

Quinince Hydrobromas, U. S. P., has the formula C 20 II 24 N 2 O 2 ,IIBr,- 
2H 2 0. 

Quinince Ilydrochloras, U. S. P., has the formula C 20 II 24 N 2 2 ,HC1,- 
2H 2 0. 

Reactions. 
First Analytical Reaction. — To a solution of quinine or its 
salts in acidulated water add fresh chlorine-water, shake, and 
then add solution of ammonia; a green coloration (thalleiochin, 
or dalleiochin) is produced. Bromine-water or bromine vapor 
may be used instead of chlorine, excess being avoided. 

* We do not know whether or not these sulphates are ordinary sul- 
phates, the hydrogen of the acid going over to the quinine molecule, 
nor whether or not the quinine molecule is univalent or bivalent ; hence 
we cannot say whether the common sulphate or the soluble sulphate is, 
in constitution, the neutral sulphate. In the above paragraph the 
names disulphate, neutral sulphate, acid sulphate, indicate nothing more 
than that the first sulphate contains in one molecule two atoms (chem- 
ical atoms) of quinine to one of sulphuric acid, the second one of each, 
and the third two oi* acid to one of quinine. 



512 THE ALKALOIDS. 

Second Analytical Reaction. — Repeat the foregoing reaction, 
but precede the addition of solution of ammonia by that of 
solution of ferrocyanide of potassium ; an evanescent red 
coloration is produced (Livonius and Vogel). 

Third Analytical Reaction. — To an aqueous solution of a 
soluble salt of quinine add solution of oxalate of ammonium ; 
a white crystalline precipitate of oxalate of quinine falls. It 
is soluble in acids. If the solution to be tested be made from 
ordinary sulphate of quinine, excess of the latter should be 
added to water very faintly acidulated with sulphuric acid, 
and the undissolved crystals removed by nitration. 

Fourth- Analytical Reaction. — A saturated aqueous solution 
of any neutral salt of quinine is made by dissolving so much 
of the salt in hot water as that some shall separate when the 
mixture has cooled to about 60° F. After standing for some 
time, filter. Evaporate to one-fifth. To the filtrate water- 
washed ether is added until a distinct layer of ether remains 
undissolved, and then ammonia in slight excess. After agita- 
tion and rest for fifteen minutes all quinine precipitated by the 
ammonia will have dissolved. 

Note. — In the case of quinidine salts well-defined crystals will ap- 
pear at the junction of the aqueous and ethereal layers, especially 
after standing. In the case of cinchonidine salts a thick layer of 
small crystals makes its appearance at once, whilst in the case of 
cinchonine salts the undissolved alkaloid is enough to make the 
ethereal layer nearly solid. 

Fifth Analytical Reaction. — Formation of Iodo-sulphate of 
Quinine. Dissolve sulphate of quinine in weak spirit of wine 
slightly acidulated with sulphuric acid, and add an alcoholic 
solution of iodine ; a black precipitate forms. Allow the pre- 
cipitate to settle, pour away the fluid, wash once or twice with 
alcohol, and then boil with alcohol ; on cooling, minute crystals 
separate having the optical properties of the mineral tourma- 
line. This iodo-sulphate is sometimes termed Herapathite, 
from the name of one of the chemists who discovered it (in 
1852). Under the name of iodide of hydriodate of quinine, 
Bouchardat described and used it in 18-15. It is so slightly solu- 
ble in alcohol that by its means quinine can be separated from 
its admixture with the other cinchona alkaloids. According to 
Jorgensen, it has the formula 4C 20 H 24 N 2 O. 2 ,3H 2 SO„2HI,I 4 ,a:H 2 O. 

Sixth Analytical Reaction. — Prepare a saturated solution of 
ordinary sulphate of quinine in water at about 60° F., and add 
to 5 volumes of that solution 7 volumes of solution of ammo- 
nia (sp. gr. 0.96). The alkaloid which at first precipitates 
redissolves upon slight agitation if the sulphate of quinine is 



QUININE. 513 

free from anything but traces of other cinchona alkaloids. 
If, however, more than traces of quinidine, cinchonidine, and 
cinchonine salts be present a permanent precipitate remains. 
This is Kerner's method of testing sulphate of quinine for 
other cinchona alkaloids. It turns upon the fact that the 
solubility of the sulphates of the cinchona alkaloids in water 
is in the opposite order to the solubility of the alkaloids them- 
selves in solution of ammonia. 

Other Characters. — Concentrated sulphuric acid dissolves 
quinine with production of only a faint yellow color, which dis- 
tinguishes it from salicin. Quinine and its salts, heated on 

platinum foil, burn entirely away. Most salts of quinine 

when in solution have a beautiful blue fluorescence. They 
twist the ray of polarized light to the left. Quinine is soluble 
in alcohol, ether, benzol, and chloroform. Ordinary quinine sul- 
phate is insoluble in chloroform, and but slightly soluble in 
water. Its solubility in chloroform is increased by the pres- 
ence in solution of quinidine and cinchonine sulphates (Pres- 
cott), and its solubility in water is decreased by the presence in 
solution of ammonium sulphate (Carles). The slight solubility 
of its sulphate and iodo-sulphate in water distinguishes quinine 
from the other cinchona alkaloids, including the " amorphous 
alkaloid," or " quinoidine." (See "Paul's test" in Index.) 

Quinidine (C 20 II 24 N 2 O 2 , the Conquinine or Conchinine of Hesse) 
is an isomer of quinine. Its salts are fluorescent, and give thal- 
leioquin with chlorine- or bromine-water and ammonia. They twist 
the ray of polarized light to the right. Quinidine is insoluble 
in water and sparingly soluble in ether (see Quinine, 4th Analytical 
Reaction). It is soluble in alcohol, benzol, and chloroform. It is 
less soluble than quinine in ammonia, 5 volumes of a saturated aque- 
ous solution of its ordinary sulphate requiring 60 to 80 volumes of 
ammonia solution (sp. gr. 0.96). Its sulphate (Quinidince Sulphas, 
U. S. P. ; 2C 20 II 2( N 2 O 2 ,II 2 SO 4 /2II 2 O) is more soluble in water and 
chloroform than the sulphate of quinine. Tartrate of quinidine is 
soluble in water. The hydriodate is insoluble in water and weak 
spirit, and occurs as sandy crystals. The hydriodates of the other 
cinchona alkaloids, though more soluble than quinidine hydriodate. 
are sometimes precipitated from neutral concentrated solutions as 
amorphous or semi-liquid precipitates. These, however, are soluble 
in weak spirit. "If 0.5 gm. each of sulphate of quinidine and of 
iodide of potassium (not alkaline to test-paper) be agitated with 10 
C.C. of water at about 60° C. (140° P.), the mixture then macerated 
at 15° (1. (59° V.) for half an hour, with frequent stirring, and fil- 
tered, the addition to the filtrate of a drop or two of water o\' am- 
monia, should not cause more than a, slight, turbidity (abs. ol' more 
than small proportions of cinchonine, cinchonidine; or quinine)." — 
U. S. P. 



514 THE ALKALOIDS. 

Cinckonidine (C 20 H 24 N 2 O). — When perfectly pure, salts of cin- 
chonidine do not give thalleioquin and are not fluorescent. Even 
good commercial salts, however, nearly always give both reac- 
tions. Salts of cinchonidine twist the polarized ray to the left. 
Cinchonidine is insoluble in water and nearly so in ether (see 
Quinine, 4th Analytical Reaction). It is soluble in alcohol, benzol, 
and chloroform. It is less soluble in ammonia solution than quinine, 
five volumes of a saturated aqueous solution of cinchonidine sulphate 
requiring about 80 volumes of ammonia solution (sp. gr. 0.96). It 
is true that cinchonidine is dissolved as readily as quinine if excess 
of strong ammonia is quickly mixed with the solution of a salt of 
cinchonidine ; but from such a solution cinchonidine soon crystallizes, 
while quinine remains dissolved for many hours. Sulphate ( Cincho- 
nidince Sulphas, U. S. P. (C M H 24 N 2 0) 2 ,H 2 S0 4 ,3H 2 0) and hydriodate 
of cinchonidine are soluble in water, but the sulphate, like quinine 
sulphate, is insoluble in chloroform. Tartrate of cinchonidine is in- 
soluble in water, and in this form cinchonidine is usually separated 
from neutral solutions containing the other cinchona alkaloids 
except quinine. 

Cinchonine (C 20 H 24 N 2 O) (Cinchonina, U. S. P.) is an isomer of 
cinchonidine. When quite pure its salts are not fluorescent and 
do not give thalleioquin. As in the case of cinchonidine, even 
good commercial specimens of cinchonia salts nearly always give 
both reactions. Cinchonia salts twist the polarized ray to the 
right. Cinchonine is insoluble in water and nearly so in ether (see 
Quinine, 4th Analytical Reaction). It is soluble in chloroform, 
benzol, and alcohol. Chloroform containing one-fourth of its 
weight of 95-per cent, alcohol dissolves cinchonine much more 
readily than either alcohol or chloroform alone. Cinchonine is 
insoluble in ammonia solution. Sulphate ( Cinchonince Sutyhas, 
U. S. P.) (C 20 H 24 N 2 O) 2 ,H 2 SO 4 ,2H 2 O, tartrate, and hydriodate of cin- 
chonine, are soluble in water, and the sulphate, like sulphate of 
quinidine, is soluble in chloroform. In mixtures of cinchona alka- 
loids this alkaloid is precipitated by alkali after the others have 
been successively removed by ether, tartrate of sodium, and iodide 
of potassium. 

Constitution of the Cinchona Alkaloids.— -This is not yet dear, 
though great advances have been made. In the course of the inves- 
tigations derivatives of quinoline, more or less resembling quinine, 
have been obtained — namely, kairine, kairoline, and thalline ; anti- 
pyrin also. Acetanilide, or "antifebrin,' 1 has, too, been found to 
possess even greater antipyretic powers than the derivatives just 
mentioned. See also p. 504. 

" Quinoidine" or the "Amorphous Alkaloid" 1 (Chinoidin, JJ. S. 
p.). — Cinchona-barks generally contain some alkaloid isomeric with 
quinine, which, like quinine, is soluble in ether, but the ordi- 
nary sulphate and iodo-sulphate of which are not crystalline and 
are soluble. These salts are semisolid, resinous-looking substances. 
The iodo-sulphate is used in Dr. Vrij's method for the separation 
of mixed alkaloids (see Index). Quinoidine is^ usually obtained 
along with quinine, etc. from the mixed alkaloids by ether, and 



STRYCHNINE. 515 

remains in the mother-liquor, from which it is precipitated by an 
alkali. If quinoidine be triturated with boiling water, the liquid, 
after filtration, should be clear and colorless, and should remain so 
on the addition of an alkali (abs. of alkaloidal salts). On ignition, 
quinoidine should not leave more than 0.7 per cent, of ash. 

Cinchovatine occurs in a particular variety of cinchona-bark. 
Quinicine and Cinchonicine are alkaloids produced by the action of 
heat on quinine or quinidine and on cinchonine or cinchonidine 
respectively. They also are isomers — Hesse says polymers — of the 
parent alkaloids. Both yield ordinary salts. Quiniretin is the 
name given to the brown or reddish-brown indifferent substance into 
which quinine in aqueous solution is converted when exposed to 
much light. 

Quinamine (C 20 H 26 N 2 O 2 ) is a fifth cinchona alkaloid obtained by 
Hesse in 1872 from the bark of Cinchona succirubra. Its solution 
is not fluorescent and does not give thalleioquin. The same chem- 
ist announces the presence in cinchona of a sixth alkaloid, cinchami- 
dine (C 20 H 26 N 2 O). 

Cupreine, C 19 H 22 N 2 2 , is an alkaloid discovered by Paul and 
Coronley in the bark of a Remijia (allied to Cinchona), and termed 
cuprea-bark. It closely resembles quinine, but it is sparingly solu- 
ble in ether. The alkaloid at first termed homoquine or ultraquinine 
seem to have been a mixture of cupreine and quinine. Hydro- 
quinine, C 20 H 26 N 2 O 2 , whose molecule contains two more atoms of 
hydrogen than are present in that of quinine, is an alkaloid associ- 
ated with quinine, in minute amount, in cinchona-bark. It remains 
in the mother-liquor when quinine sulphate is crystallized from an 
acid solution. Its therapeutic action is similar to that of quinine. 
Its chemical characters are closely allied to those of quinine. It 
was discovered by Hesse. 



STRYCHNINE, OR STRYCHNIA. 

Formula C 21 H 22 N 2 2 . Molecular weight 334. 

Source. — This alkaloid (Strychnina, U. S. P.) exists, to the extent 
of 0.2 to 0.5 per cent., in the seed of Slrychnos Mix Vomica (Xux 
Vomica, U. S. P.), also (Shenstone) in minute quantity in the bark 
of the Nux Vomica tree (false Angustura-bark), and to 1.0 or 1.5 
per cent, in St. Ignatius's bean (Strychnos Ignatia) (Igriatia, U. S. P.), 
chiefly in combination with strychnic or igasuric acic, or, after slight 
fermentation when moistened, with lactic "acid. Crow also found it 
in the bark of S. Ignatia. 

Process. — According to the British official process for its prepara- 
tion, the nuts, disintegrated by subjection to steam, and. after drying, 
grinding in a coffee-mill, are exhausted with spirit, the latter removed 
by distillation, the extract dissolved in water, coloring and arid mat- 
ters precipitated by acetate of lead, the filtered liquid evaporated to 
a small bulk, the strychnine precipitated by ammonia, the precipitate 
washed, dried, and exhausted with spirit, the spirit recovered by dis- 



516 THE ALKALOIDS. 

tillation, and the residual liquid set aside to crystallize. Crystals 
of strychnine having formed, the mother-liquor (which contains the 
brucine of the seeds) is poured away, and the crystals of strychnine 
washed with spirit (to remove any iDrucine) and recrystallized. 

In the U. S. P. (1870) process the rasped Nux Vomica is exhausted 
by very dilute hydrochloric acid, milk of lime added to the evap- 
orated decoction to decompose the hydrochlorate of strychnine, the 
precipitated and dried mixture of strychnine and lime treated with 
diluted alcohol to remove brucine, and then with strong, hot alcohol 
to dissolve out strychnine ; the alcohol having been recovered by dis- 
tillation, the residual impure strychnine is dissolved in very dilute 
sulphuric acid, the solution decolorized by animal charcoal, evap- 
orated, and set aside to crystallize, the crvstals of sulphate of strych- 
nine {Strychnines Sulphas, U. S. P. ; (C 21 H 22 Ay3 2 ) 2 H 2 S0 4 ,7H 2 0; Cole- 
man, 6H 2 0) redissolved in water, ammonia added to precipitate pure 
strychnine, and the latter dried. It is soluble in about 40 parts of 
water. The citrate (C 2} H 22 N 2 Q 2 ) 2 C 6 H 8 7 ,4II 2 (or 2H 2 0) at common 
temperatures dissolves in 45 parts of water and 115 parts of alcohol. 

Properties. — Strychnine occurs " in right square octahedrons or 
prisms, colorless and inodorous; sparingly soluble in water, but 
communicating to it its intensely bitter taste •, soluble in boiling 
rectified spirit and in chloroform, but not in absolute alcohol or in 
ether." 

Reactions. 

First Analytical Reaction. — Place a minute particle of 
strychnine on a white plate, and near to it a small fragment of 
red chromate of potassium ; to each add one drop of concen- 
trated sulphuric acid ; after waiting a minute or so for the 
chromate to fairly tinge the acid, draw the latter, by a glass 
rod, over the strychnine spot ; a beautiful purple color is pro- 
duced, quickly fading into a yellowish-red. The following 
oxidizing agents may be used in the place of the chromate : 
puce-colored oxide of lead, fragments of black oxide of man- 
ganese, ferridcyanide. of potassium, or permanganate of potas- 
sium. 

This reaction is highly characteristic : a minute fragment dissolved 
in much dilute alcohol — or, better, chloroform — and one drop of the 
liquid evaporated to dryness on a porcelain crucible-lid or other white 
surface, yields a residue which immediately gives the purple color on 
being oxidized in the manner directed. 

Other Reactions. — Strong sulphuric acid does not decompose strych- 
nine even at the temperature of boiling water, a fact of which advan- 
tage is taken in separating strychnine from other organic matter for 

purposes of toxicological analysis. Sulphocyanicle of potassium 

produces, even in dilute solutions of strychnine, a white precipitate, 
which under the microscope is seen to consist of tufts of acicular 

crystals. Strong nitric acid docs not color strychnine in the cold, 

and on heating only turns it yellow. 



STRYCHNINE. 517 

The Physiological Test. — A small frog placed in an ounce of water 
to which y^q of a grain of a salt (acetate) of strychnine is added is in 
two or three hours seized with tetanic spasms on the slightest touch, 
and dies shortly afterward. 

Strychnine has an intensely bitter taste. Cold water dissolves only 
wooij P ar fc, y e ^ this solution, even when largely diluted, is distinctly 
bitter. Alcohol is a somewhat better solvent. The salts of the alka- 
loid are more soluble. The Liquor Strychnice, B. P., contains four 
grains of strychnine to the ounce, the solvent being three parts water, 
one part spirit, and a few minims (6 per ounce) of hydrochloric acid 
(rather more than sufficient to form hydrochlorate of strychnine). A 
syrup of Phosphates of Iron, Quinine, and Strychnine is official {Syr- 
upus Ferri, Quinince, et Strychnince Phosphatum). It contains 1 part 
of strychnine in 2500. 

Brucine, or Brucia (C 23 H 26 N 2 4 ,4II 2 0), is an alkaloid accom- 
panying strychnine in Nux Vomica and St. Ignatius' s bean to the 
extent of about 0.5 per cent. It is readily distinguished by the 
intense red color produced when nitric acid is added to it. 
Igasurine, once supposed to be a third alkaloid of nux vomica, 
has been shown by Shenstone to be only a mixture of brucine and 
strychnine. 

Curarine (C 10 II 15 N), the active principle of the arrow-poison 
termed urari, ourari, wourali, or ivoorara, prepared from a Strych- 
nos, resembles strychnine in giving color by oxidation, but the color 
is more stable. Iodide or platino-cyanide of potassium does not 
with curarine afford precipitates which crystallize from alcohol like 
those of strychnine. Curarine also is soluble in water. Unlike 
strychnine, curarine is reddened by sulphuric acid ; it, also, is not 
dissolved out by ether from an acid or alkaline liquid. Curari 
appears to vary much in strength and quality. It is probably a 
mixture of vegetable extracts. 

Distinction of Brucine from Morphine. — The red coloration pro- 
duced by the action of nitric acid on brucine is distinguished from 
that yielded by morphine by the action of reducing agents (such as 
stannous chloride, hyposulphite of sodium, sulphydrate of sodium), 
which decolorize the morphine red, but change that of the brucine to 
violet and green (Cotton). 

Distinction of Free Alkaloids or their Salts from Each Other. — 
This is accomplished by remembering the appearance and other 
physical characters of the substances as met with in pharmacy, the 
effect of heat, the action of such solvents as water, alcohol, and 
ether, the influence of strong and diluted acids, strong and weak 
alkalies, oxidizing agents, chlorine-water and ammonia, and other 
reagents. (See annexed Tables, I. and II.) 



QUESTIONS AND EXERCISES. 

828. What alkaloids are more or less characteristic of the differ- 
ent varieties of cinchona-bark? In what form do they occur? 

829. By what method is Disulphate of Quinine obtained? 



518 THE ALKALOIDS. 

830. Give the characters of disulphate of quinine. 

831. Describe the tests for quinine. 

832. How is the adulteration of disulphate of quinine by salicin 
detected ? 

833. Show how the sulphates of quinine or cinchonine may be 
proved to be present in commercial quinine. 

834. How are cinchonine and quinine distinguished from morphine ? 

835. Whence is strychnine obtained ? 

836. Describe the official process for the isolation of strychnine. 

837. Give the characters of strychnine. 

838. Enumerate the tests for strychnine, and describe their mode 
of application. 

839. By what reagent is brucine distinguished from strychnine? 

840. Distinguish between brucine and morphine. 

841. By what general methods would you distinguish common 
alkaloids from each other? 



Analytical Exercises. — Analyze small quantities of alkaloids, their 
salts, and various " scale ,: compounds by aid of the annexed Tables, 
I. and II. 



ALKALOIDS OF LESS FREQUENT OCCURRENCE. 

Aconitine, Aconitina, or Acoxitia is an alkaloid obtained from 
aconite (Aconitinn Kapellus) leaves (Aconiti Folia, B. P.) and root 
{Aconitinn, U. S. P.). The alkaloid itself is only slightly soluble in 
water ; it occurs in the plant in combination with a vegetable acid, 
forming a soluble salt. 

Process. — The process for the preparation of Aconitine, B. P., con- 
sists in dissolving out the natural salt of the alkaloid from the root 
by rectified spirit, recovering the latter by distillation, mixing the 
residue with water, filtering, precipitating the aconitine by ammonia, 
drying the precipitate and digesting it in ether (in which some of 
the accompanying impurities are insoluble), recovering the ether by 
distillation, dissolving the dry residue in the retort in water acid- 
ulated by sulphuric acid, again precipitating the alkaloid by ammo- 
nia, and finally washing and drying. 

Properties. — Aconitine usually occurs as a white powder, but has 
been obtained and studied in the crystalline state by Groves, Wright, 
Williams, and others. It is very slightly soluble in cold water, 
more so in hot, and is much more soluble in alcohol and ether. 
It is one of the most violent poisons known. " When rubbed on 
the skin it causes a tingling sensation, followed by prolonged 
numbness." 

The thousandth part of a grain on the tip of the tongue produces, 
after a minute or so, a characteristic tingling sensation and numb- 
ness ; larger quantities rubbed into the skin cause numbness and 
loss of feeling. Sulphuric acid turns it to a yellowish, and after- 
ward dirty-violet, color. 









rtiyJtfy acidified with hjdroo 






To face page 518.] 



I. TABLE FO 



Morphine. 
Brucine. 



Salicin. 
Strychnine. 



To a small quantity on a 
white plate add strong nitric 
acid. 



An Orange 
Color, de- 
colorized by 
SnCl 2 , Na 2 S 2 
3 , or NaHS 
= Mo rp hine. * 
Confirm by — 
Fe 2 Cl 6 (neut.), 
which gives 
with mor- 
phine or its 
salts a blue 
color. 

HIO3 is de- 
composed by 
morphine or 
its com- 
pounds, with 
liberation of 
iodine, which 
may be re- 
cognized by 
starch. 

* Strychnine 
of commerce 
often gives an 
orange or red 
color, due to 
contamination 
with brucine. 



A Red Color. 
To a few 
grains in a 
test-tube add 
a drop or two 
of HNO3 J 
warm to boil- 
ing and dilute 
with water ; 
then add a 
few drops of 
stannous chlo- 
ride. 

A violet col- 
or = Brucine. 



If no Morphine or Brucine, 
moisten a small quantity on 
a white plate with strong 
suljjhuric acid. 



A deep red 
color = Sali- 
cin. 

Confirm by 
boiling the 
substance 
with water to 
which has 
been added a 
few drops of 
dilute H2SO4. 
Then make 
solution alka- 
line and ex- 
amine for glu- 
cose. 



No color, or 
only a slight 
color. 

Draw a mois- 
tened crystal 
of K 2 Cr 2 C>7 
across the 
acid film when 
a transient 
play of colors, 
violet to red 
= Strychnine. 



I 

ab& 

an( 

ta ^eutral solution, di- 

sta two portions, and 

ne Vs:— 

tesl 

the 

anc 



iy ' 

ethe^ 
T'ed 
the ,es 
aqute. 
add 
tha 5 h 
of by 
twt ( 
ami 






pha 
If 
doe 
com 
ano 
the 
tion 
and 
pre< 
witl 
pha 
A 
line 
Qui 
Co 



Second por- 
tion. 
If no ace- 
tic or meco- 
nic acid, add 
AgN0 3 .' 

Precipitate 
(white, with a 
tendency 
darken) s 
uble in HNO3 
= Gitr-ic Acid. 
Confirm by 
adding CaCl 2 
to a neutral 
cone, solution 
and boiling 
when a white 
precipitate of 
citrate of cal- 
cium sepa- 
rates. 



To face pag 


518.] 




I. TABLE 


FOR THE IDENTIFICATION OP TI 
(Compiled by A. S 


mm:. M 


INQ ALKAL 




ETC. 






SSET S£S™ &*. £Z£S* 


AC IB S.{|=^. gjc 


jf^SL«JK 


S^S-S 


1 I I \ 


sSas?-- 4551 ^- 


;i Sj;,:.:"»;:£Si 


pnine Titi 


:'..' '"''ii'n!" ' 


| ',"■;., :,ir„, ( l,y 




i'i.„;",",'!j L : r'. (!■'".. 

*X"' - t other 


11, "« '!,„.] ,',:,',.' 

1 ,1 'l 'l' l' 
spirit. 


EH 




\.ii igNOj. 


\',j..i „...i/i'.. 

boil. '' A j°l- 

);;,'.'„, ■i'A,-i"i." 


r|% 


UN",'. 



To face page 518. 



JE COMPOUNDS. 



ted into pyrophosphoric). 



Dissolve a portion \ 
loids (except Strychni;Heat the ash with HNO3, 
little ether, and separinium molybdate in HNO3, 
solution, and insoluble 



Ethereal S\. 



ellow Precipitate. 



May contain quinir. 
bebenne. To solutior^ some of the aqueous solu- 
add H 2 0, very slightl\ H0 > filter > and add to a P or " 
HC2H3O2 and boil, burr nitrate a slight excess of 
To a portion of the divide into two parts. To 
add CI or Br water C1 2 (precipitate = Sulphuric 
NH4HO. tne other add AgN03 (pre- 

tydrochloric Acid). Neutral- 
portion of the KHO filtrate 
•^ and add AgN03. 



Green Color 
(thalleioquin). 



Solutionis fluor- 
escent, and con- 
tains either qui- 
nine or quinidine. 
Concentrate the re- 
mainder of the so- 
lution and divide 
into two parts. To 
one add KI, and 
to the other add 
(NH 4 ) 2 C 2 4 . 

KI precipitates 
quinidine, not qui- 
nine. 

(NH 4 ) 2 C 2 04 pre- 
cipitates quinine, 
not quinidine. 

For another 
method, see tho 
third division of 
the annexed Table 
(I.) for alkaloids, 
using 40 or 50 
grains of material. 



ATE 

± , Slack. 

tnl 

ad 

lo{ 



little 



cirf 



issolve 
recipi- 
at. A 
= Tar- 

Ja2HO 
keutral 
ioncen- 
je cold, 
Lte re- 
li boil- 



Precipitate 

White. 



Citric acid gives 
no mirror. CaCl 2 
and Ca2HO do not 
precipitate citric 
acid in the cold, 
but upon boiling 
(if solution be 
sufficiently concen- 
trated) precipita- 
tion occurs. 



S . r Ammonium (often as 
<; [5 | a contamination). 
O m \ Ferric Iron. 
PS < Potassium. 






[ Sodium. 



Ammonium. — Boil aqueous 
solution of scale with KHO 
and test vapor for NH3. 
Filter and dissolve precipi- 
tate in HC1, and test the so- 
lution for Iron by K 4 FeCy6, 
KCyS, etc. 

Potassium and Sodium. — 
Ignite a small quantity of 
the scale, and moisten the 
residue with water. Test 
moistened residue with lit- 
mus-paper. If alkaline, ex- 
amine for potassium and 
sodium by the color im- 
parted to flame, and for po- 
tassium by HC1 and PtCl 4 . 



\rtaric or Citric Acid.— To slightly acidified KHO filtrate 
in slight excess and considerable quantity of NH4CI and 
Iratcs are precipitated completely in the cold with agita- 
, for about ten minutes. To the solution (or filtrate it' 
j present") add three volumes of spirit of wine, when 
precipitated. If sulphates have been found, disregard 
itate with spirit of wine. 











PVROPHOSPHORIC 









fQlUMNF 

ALKALOIDS. (Ji imi.i 






1 


||Ei:;"L~ dmto 




p 


£vr 


11. neons 




:.1||e^ 




i^M,, W.'ill'l 


Ign 


j;rrK^i^: 


wtfasa 


ESS 


E ™ a..™.. 


S,P^ E . £ 


^-™ 


No*,™ 




: ; : :':v ;.'',.:,. .'.■■ '':.■.; 


:i§3 


;l,l ; ;'!:;:::: 




and add AgNOj! "' 


," ,,! " :, 




to* and Tpart 


an™ 


Wl 


te pre- 


Wl,i,, ,„ 


J&S3S 


NoG^Cco, 




'!■"• 


,' ; ,:: 


s 


"'„.'.' 


,,a:!,C;/'.i,w. 


«,tl. IIMljundad 


AgM*,. 




G :™:::\":.. 


'TbSL 1 ™ 


1 '"' 


'Vi;;!:.''' 1 ';-.; 


Add . . ■ 




;: • ; .", 


cipitate=.Bc4en ne . 






i . ". 










Si; ",;;.. 2 






iMI,'V"','." 






■s 


°iSCr 








f'^X"'''^''" 


i"''';'.i: n '|^''!|)i-!:: 






,",'";' ■ 
















iiJlv-4o\boil- 








For another 
















Confim, Tartaric 


,WrW««.-T.. 


,,„h :„-,i,f, 1 K 




























■m',: ,„":,;■: ,','; 


















■ .-. ,.: se J 




db££3 



ATROPINE. 519 

According to Wright, who, in conjunction with Groves and Williams, 
worked by aid of grants from the British Pharmaceutical Conference, 
Aconitum napellus yields crystalline aconitine, C 33 H 43 NQ 12 , crystal- 
line pseud-aconitine, C 36 H 4! ,N0 12 , and a non-crystalline alkaloid. 

According to J'urgens, the formula of aconitine is C 33 H 47 N0 12 . 
On allowing an acetic solution containing iodide of potassium to 
evaporate to dryness, and then adding water, crystals of hydriodate 
of aconitine of characteristic appearance remain. 

The tuberous roots of Aconitum ferox and other species constitute 
the bish or bikh of India {Aconiti ferocis Badix, P. I.). It chiefly 
contains the variety of aconitine termed pseud-aconitine. Some of 
the aconitine of pharmacy is pseud-aconitine. According to Paul 
and Kingzett, the alkaloid of Japanese aconite has the formula 
C 29 H 43 N0 9 , while Wright and Menke state that the formula is 
C 66 H 88 N ? 2 , and name it japaconitine. 

Aconitum heterophyllum Atis, or Atees, or Walchuma {Aconiti 
heterophylli Radix, P. I.), contains no aconitine, but an alkaloid, 
ateesine, having the formula C 46 II 74 N 2 5 . 

Aspidospermine is an alkaloid of Quebracho bianco bark (Fraude). 
Another and different alkaloid is qwebrachine (C 2] II 26 N 2 3 ) (Hesse). 
The latter chemist has isolated four other closely-related alkaloids, 
and two from Quebracho Colorado bark. 

Atropine, or Atropia (C 17 H. 23 N0 3 ). — This alkaloid has hitherto 
been considered to exist only in the Belladonna, or Deadly Night- 
shade {Atropa belladonna ; Belladonna? Folia et Radix, U. S. P.), as 
soluble acid malate of atropine. But the observations of Messrs. 
Schering and the researches of Will indicate that not atropine, but 
an isomei-of atropine — namely, hyoscyamine — is the alkaloid chiefly 
and solely present, and that the alkaline treatment during the pro- 
cess of extraction converts the hyoscyamine into atropine. Hyoscy- 
amic solutions rotate a plane polarized ray to the left ; atropine has 
no optical rotatory power. Each similarly affects the eye. 

Process-. — Atropine is obtained by exhausting the root with spirit, 
precipitating the acid and some coloring-matter by lime, filtering, 
adding sulphuric acid to form sulphate of atropine (which is some- 
what less liable to decomposition during subsequent operations than 
the alkaloid itself), recovering most of the spirit by distillation, add- 
ing water to the residue, and evaporating till the remaining spirit is 
removed ; solution of carbonate of potassium is then poured in till 
the liquid is nearly but not quite neutral, by which resinous matter 
is precipitated; the latter is filtered away, excess of carbonate of 
potassium then added, and the liberated atropine dissolved out by 
shaking the liquid with chloroform. The latter solution, having 
subsided, is removed, the chloroform recovered by distillation, the 
residual atropine dissolved in warm spirit, coloring-matter separated 
by digesting the liquid with animal charcoal, the solution filtered, 
evaporated, and set aside to deposit crystals. 

Solubility. — Atropine is sparingly soluble in water, the liquid giv- 
ing an alkaline reaction— more soluble in alcohol and ether. 

Tests. — Atropine solutions give with perchloride oi' gold a yellow 



520 THE ALKALOIDS. 

precipitate. One drop of a dilute aqueous solution (two grains to 
the ounce) powerfully dilates the pupil of the eye. It is generally 
applied on a piece of thin tissue-paper or small disk placed between 
the eyelid and the eye. Gerrard, Schmeissinger, and Fliickiger 
have observed that atropine, like lvyoscyamine and homatropine 
(Ladenburg's oxytolulyltropeine, a physiologically similar, but less 
powerful and therefore sometimes more useful, alkaloid than atro- 
pine), has unusually powerful alkaline properties, precipitating mer- 
curic oxide from mercuric solutions, reddening phenolphthalein, and 
with warmth, blackening calomel. No other ordinary alkaloids are 
so powerfully alkaline. 

Baryta-water decomposes atropine into tropine (C 8 H 15 NO) and 
tropic acid (C 9 H ]0 O 3 ), a molecule of water being absorbed ; hence 
the atropine so called would seem to be tropate of tropine. Indeed, 
Ladenburg by combining tropic acid and tropine has produced a 
base indistinguishable from atropine. The same chemist by remov- 
ing the elements of water from tropine gets tropidine, C 8 H 13 N. 
This is, possibly, an intermediate member of a group of mon- 
amines of which others are canine, C 8 II 15 X, and collidine, CyH^X, 
the latter a product of the destructive distillation of bone-oil, coal, 
quinine, etc. 

Commercial atropine is said by Regnauld and Yalmont to be a 
mixture of true atropine with hyoscy amine. 

In the so-called Japanese belladonna {Scopolia Japonico) occurs 
scopoleine (Eykman), an alkaloid resembling, but more powerful 
than, atropine ; but Schmidt considers that only atropine, hyoscy- 
amine, and hyoscine are present. 

Preparations. — The alkaloid itself {Atrophia) and its sulphate 
{Atropines Sulphas, (C n H 23 X0 3 ) 2 H 2 S0 4 , a colorless powder soluble 
in water, made by neutralizing atropine with sulphuric acid) are 
official in the United States Pharmacopoeia. 

The fluorescence of alkaline solutions of extract of belladonna is 
caused by chri/satropic acid, C 12 H 10 O 5 (Kunz), probably allied to 
Eykman*s scopolelin, C 10 II 8 O 4 , the fluorescent principle of Japanese 
belladonna-root. 

Baptitoxine. — Schroeder gives this name to a poisonous alkaloid 
in Baptisia thictoria, Wild Indigo, in which he also finds the gluco- 
sides baj)tisin and baptin. 

Beberixe, Bebirine. Beberia, or Bibirina (C ]8 H 21 N0 3 ), an alka- 
loid existing in the bark of Bebeeru or Bcbise {Nectandra Rodicei). 

Process. — According to the British Pharmacopoeia, it, or rather its 
sulphate, C 3r> Il 42 N 2 O r) .H 2 S0 4 {Beherice Sulphas, B. P.), may be pre- 
pared by exhausting the bark {Nectandro3 Cortex, B. P.) with water 
acidulated by sulphuric acid, concentrating, removing most of the 
acid by lime, filtering, precipitating the alkaloid by ammonia, filter- 
ing, drying, dissolving in spirit (in which some accompanying mat- 
ters are insoluble), recovering most of the spirit by distillation, neu- 
tralizing by dilute sulphuric acid, evaporating to dryness, dissolving 
the residual sulphate in water, evaporating to the consistence of a 
syrup, and spreading on glass plates, drying the product at 140° F. 



BERBERINE. 521 

Thus obtained, it occurs in thin dark-brown translucent scales, yel- 
low when powdered, strongly bitter, soluble in water and in alcohol. 
It is probably not a single definite salt. 

Tests. — Alkalies give a pale-yellow precipitate of beberine when 
added to an aqueous solution of a salt of the alkaloid ; the precipi- 
tate is soluble in ether. With red chromate of potassium and sul- 
phuric acid beberine gives a black resin, and with nitric acid a yel- 
low resin. 

Buxine, from the bark of Buxus sempervirens ; Pelosine, or Ciss- 
ampeline, from the root (Pareira, U. S. P.) of Chondodendron tomen- 
tosum ; and Paricine, from a false Para cinchona-bark, are probably 
identical with Beberine (FlUckiger). 

Nectandrine (C 20 H 23 NO 4 ). — Drs. Maclagan and Gamgee a few years 
ago discovered this second alkaloid in Bebeeru-bark. It differs from 
beberine in fusing when placed in boiling water, in being much less 
soluble in ether, in giving with strong sulphuric acid and black oxide 
of manganese a beautiful green and then violet coloration, and in 
having a distinct molecular weight. They gave the opinion that two 
other alkaloids exist in Bebeeru-bark. 

Berberixe, or Berberia (C 20 II n NO 4 ,4H 2 O) is an alkaloid existing 
in several plants of the natural order Berberidece (three species yield 
Indian Barberry, Berberis Cortex. P.. I.), in Calumba-root (Calumba, 
U. S. P.), Goldthread ( Coptis trifolia), according to Mayer in the root 
of Coptis Suta, or Nieshnic Bitters (Captidis Radix, P. I.), an Indian 
tonic, and in many yellow woods. Hydrastis canadensis, Yellow-root 
or Golden Seal (Hydrastis, U. S. P.), contains berberine. though 
another alkaloid, hydrastine (C 22 H 23 N0 6 ), related to narcotine, and 
even a third, are said to be present. The root of Berberis vulgaris 
contains berberine and (Waker) oxyacanthine (C 18 H ]9 NO ;{ ), as well as 
(Hesse) berbamine (also ■C 18 II 19 N0 3 ). Xanthorrhiza apiifolia, an old 
American tonic, and, apparently, Xanthoxylumfraxineum, or Prickly 
Ash bark (Xantlioxyhnn, U. S. P.), also contain berberine. The rhi- 
zome of Menispermum canadense, Yellow Barilla or Canadian Moon- 
seed (Menispermum, U. S. P.), contains, according to Maisch, a color- 
less alkaloid as well as berberine. The color of the tissues of these 
vegetables is apparently due to berberine, for the alkaloid itself is 
remarkable for its beautiful yellow color. 

Tests. — AVhen a dilute solution of iodine in iodide of potassium is 
added to a solution of any salt of berberine in hot spirit, excess of 
iodine being carefully avoided, brilliant green spangles are deposited. 
The reaction is sufficiently delicate to form, according to Perrins, an 
excellent test of the presence of berberine. This iodo-compound 
polarizes light, and has other analogies with a similar quinine-salt 
termed Ilerapathite. 

Berberine is not an official alkaloid, but the plants in which it 
occurs are used as medicinal agents in all parts of the world. 

Process. — Berberine is readily extracted by boiling the raw mate- 
rial with water, evaporating the strained liquid to a soft extract, 
digesting the residue in alcohol, recovering the alcohol bv distilla- 
tion, boiling the residue with diluted sulphuric acid, filtering, and 
44 * 



522 THE ALKALOIDS. 

setting aside ; the sulphate of berberine separates out, and may be 
purified by recrystallization from hot water. The alkaloid itself is 
obtained by shaking hydrate of lead with a hot aqueous solution of 
the sulphate of berberine (Proctor). 

Caffeine. — See Theine. 

Capsicine. — M. Felletar obtained from capsicum-fruits (Capsicum, 
U. S. P.), which when ground form Cayenne Pepper or African Pep- 
per, a volatile alkaloid having the smell of coniine. Thresh has 
obtained crystalline hydrochlorate and sulphate. The latter chem- 
ist has also succeeded in isolating the active principle of capsicum, 
which he has termed capsaicin (C 9 H u 0. 2 ), a crystalline, non-alka- 
loidal, excessively acrid substance. Its exact chemical character is 
not yet made out. (See also Capsicin in Index.) 

Chelidonine (C ]9 H 17 N 3 3 ) and Chelerythrine (C 19 H n N0 4 ), the 
latter identical, apparently, with sanguinarine, are two alkaloids 
occurring in Celandine (Chelidonwm, U. S. P.), associated with 
citric, malic, and chelidonic (C 7 H 4 6 ) acids. 

Cocaine (C 16 H 19 N0 4 ) is an alkaloid of Erythroxylon coca {Ery- 
throxylon, U. S. P.), the leaves of which are powerfully restorative 
to the human system. It may be obtained by agitating with kero- 
sene oil a strong acidulated aqueous extract made alkaline with car- 
bonate of sodium ; Avell shaking the separated oily fluid with acid- 
ulated water ; treating the separated acid fluid with ether and excess 
of carbonate of sodium ; washing out the alkaloid from the ether by 
water acidulated by hydrochloric acid ; and finally evaporating the 
resulting aqueous solution of the hydrochlorate at a low tempera- 
ture to the crystallizing point. The product may be recrystallized 
from alcohol or warm benzene. It occurs " in colorless acicular 
crystals, readily soluble in water, soluble in alcohol, amylic alcohol, 
and chloroform, very slightly in ether. Its solution in water has a 
bitter taste; gives a yellow precipitate with chloride of gold, and 
a white precipitate with ammonia. Its solution produces on the 
tongue a tingling sensation followed by numbness. The aqueous 
solution dilates the pupil of the eye. It dissolves without color in 
cold concentrated acids, but chars with hot sulphuric acid.'' Besides 
its action as a restorative when taken internally, cocaine brought 
into contact with the mucous membrane of the eye, mouth, throat, 
etc. produces local anaesthesia. According to Squibb, good coca 
yields about 0.5 per cent, of cocaine. 

Prolonged contact of cocaine with hot water, acids, alkalies, or even 
alcohol, is undesirable, as cocaine readily breaks up into benzoyl-ecgo- 
nine and methylic alcohol, C 17 H 21 N0 4 + H 2 = C 16 H 19 N0 4 + CII 3 OH, 
benzoyl-ecgoninc afterward yielding ecgonine and benzyol-hydrate 
or benzoic acid, C 16 H 19 NO t ~f- II 2 = C 9 H 15 N0 3 -+- C 7 II 6 2 . In coca 
other bases occur with cocaine. Hesse finds cocainine and cocaidine, 
isomeric with cocaine. Liebermann finds several bases, one of which 
is poisonous — namely, isairopy) 'cocaine, Q,, ) H 23 N0 4 , containing isa- 
tropyl in place of the benzoyl group in ordinary cocaine. It has an 
amorphous and sticky appearance. All these bases are easily hydro- 



COLCHICINE — CONIINE. 523 

lyzed, yielding ecgonine ; the latter with benzoic anhydride yields 
benzoyl-eegoninc ; and this with iodide of methyl or otherwise yields 
benzoyl-methyl-eegonine or ordinary cocaine. By thus building up 
with other acidulous bodies than the benzoic a whole chemical series 
of "cocaines'* can be produced. Cocaine itself is very slightly sol- 
uble in water or in diluted alcohol. It is soluble in strong alcohol 
or in ether. Its aqueous solution is unstable, but the aqueous solu- 
tion of the hydrochlorate is quite stable. 

Colchicine, the active principle of Colchicum autumnale {Colchici 
Radix; Colchici Semen, \J. S P.), is said to be an alkaloid, though 
some investigators think it has more of the characters of a neutral 
substance and give it the name Colchicin. Hertel gives it the form- 
ula C 17 H 23 N0 6 , and states that ebullition with acidulated water con- 
verts it into colchicein, C 17 H 2] N0 5 ,2II 2 0, and methyl alcohol. Zeisel 
says it may be crystallized from chloroform, and offers the following 
formula for it and its derivative: colchicin, C 21 II 22 (OCII 3 )N0 5 ; col- 
chicein, C 21 H 22 (OH)N0 5 . It needs further examination. The most 
active medicinal preparation is an extract made from the fresh seeds 
by digestion in large volumes of alcohol of at least 90 per cent., and 
subsequent digestion of the marc in hot water. The extracts left 
on evaporating the two fluids separately are to be carefully mixed 
(Mols). 

Coniine, Conicine, Cicutine, Conia, or Conylia. Formula 
C 8 II 17 N (Hofmann). — This alkaloid is a volatile liquid occurring in 
hemlock (Coniiim maculatum) in combination with an acid (malic?). 
It is not official. According to Petit, its boiling-point is 170° C, 
and its density 0.846. It forms crystalline salts. 

Process-. — It maybe obtained by distilling hemlock-fruit (Coniinn, 
U. S. P.) with water rendered slightly alkaline by caustic soda or 
potash, or by similarly treating the fresh juice of the leaves. The 
alkaloid is a yellow oily liquid floating on the water that distils over; 
by redistillation it is obtained colorless and transparent. 

The salts of coniine have no odor, but when moistened with solu- 
tion of an alkali yield the alkaloid, the strong smell of which, at 
once recalling hemlock, is characteristic. Extract of hemlock-leaves 
(Conii Folia, B. P.), to which solution of potash and boiling water 
have been added, forms the official Inhalation of Coniine (Vapor 
Conice, B. P.). 

Tests. — Sulphuric acid turns coniine purplish-red. changing to olive- 
green, nitric acid a blood-red ; perchloride of gold produces a yel- 
lowish-white precipitate, perchloride of platinum no precipitate, in 
aqueous solutions. 

Hemlock also contains methyl-coniine (C 8 II 14 ) // CII a X 2 ? (Kekulee 
and Van Planta), and conhi/drine, C 8 H 17 NO. 

According to SchifT, coniine, isomeric, at least, with the natural 
alkaloid, maybe produced artificially by action of ammonia on buty- 
ric aldehyde and destructive distillation of the resulting compound. 

Ladenburg has produced conine, identical with the natural alka- 
loid, from Alpha-picoline. Conine may now therefore he said to he 
a product of organic synthesis, producible from its elements. 



524 THE ALKALOIDS. 

Corydaline, Corydalina, or Corvdalia, is an alkaloid obtained 
by Wenzell from " Turkey Corn," the tubers of Dicentra (corydalis) 
formosa. 

Cusparia or Cusparine (C 19 H 17 N0 3 ) is an alkaloid occurring with 
galipeia or galipeine, (C 20 H 21 NO 3 ) in the bark of Galipea Cusparia, 
or true angustura-ba.v'k. 

Daturine, or Daturia. — Vide Hyoscyamine. 
. Delphinine, Delphine, or Delphia (C 24 H 35 N0 2 ), the poisonous 
alkaloid of Stavesacre, Delphinium staphisagria (Staphisagria, U. 
S. P.). The powdered seeds of the plant are employed to kill the 
pediculi of animals. 

Ditamine (Jobst and Hesse), the Ditain of Gruppe, is the alka- 
loid of " Dita," or bark of Echites scholaris or Alstonia scholaris 
(Alstonice Cortex, P. I.), a reputed febrifuge. Oberlin and Schlag- 
denhauffen state that the allied Alstonia constricta (the bark of which 
is said to have advantages over the hop as a dietetic bitter) contains 
a crystalline alkaloid alstonine and uncrystallizable alstonicine. 
Alstonine seems to be allied to strychnine. 

Duboisine. — Vide Hyoscyamine. 

Emetine, or Emetia (C 30 H 44 N 2 O 4 , Glenard ; C 30 II 40 ]\ T . 2 O 5 , Kunz). — 
This alkaloid is the active emetic principle of the root of Cephailis 
ipecacuanha (Ipecacuanha, U. S. P.). It occurs to the extent of 1 to 2 
per cent. (Ransom) in combination with ipecacuanhic acid. The 
nitrate is peculiarly slightly soluble in water (Lefort). In the Pulvis 
Ipecacuanhce et Opii, U. S. P., or "Dover's Powder" (Powdered 
Ipecacuanha, 1 part; Powdered Opium, 1 part; and Sugar of Milk, 
8 parts), minute division of the active ingredients is promoted by 
prolonged trituration with the sugar of milk, which is hard. Cho- 
line has been found in ipecacuanha ; Arndt also reports the presence 
of a volatile base. The Indian substitute of Ipecacuanha is the dried 
leaf (Tylophorce Folia, P. I.) of Tylophora asthmatica. Its active 
principle has not been satisfactorily isolated. 

Gelsemine, or Gelseminia (C n H ig N0 2 , Sonnenschein ; C 12 H u X0 2 , 
Gerrard ; C 54 H 69 N 4 12 , Thompson), is the alkaloid of Gelsemium 
sempervirens, or Carolina Yellow Jasmine (Gelsemium, U. S. P.), in 
the tissues of which plant the gelseminic acid of Wormley and 
cL'sculin (C 30 II. u O 19 ), the fluorescent glucoside of the Horse-Chestnut 
and of many other plants, are also present. Like strychnine, gelse- 
mine is not, apparently, affected by strong sulphuric acid. Nitric 
acid does not color it. A mixture of sulphuric acid and peroxide of 
manganese yields with gelsemine a crimson-red color, changing to 
green. In Gelsemium elegans Crow finds an allied alkaloid which 
does not resist the action of strong sulphuric acid. 

Grindeline is the name given by Fischer to a bitter crystalline 
alkaloid be extracted from Grindelia fiobusta (Grindelia ; Extractum 
Grindelia Fluidum, U. S. P.). The plant also contains resin and 
volatile oil. 

Guarine. — See Theine. 



HYOSCYAMINE — LOBELINE. 525 

Hyoscyamine, or Hyoscyamia (C ]7 H 23 N0 3 ), occurs in the leaves 
(Hyoscyamus, U. S. P.), seed, and other parts of Henbane and of 
Belladonna. It forms colorless brilliant needles ; its salts also are 
crystalline. Its effect on the eye is similar to that of atropine. The 
researches of Ladenburg show that hyoscyamine is the tropate of 
an alkaloid homologous with tropine. (See Atropine.) 

Sulphate of Hyoscyamine, (C ]7 II 23 N0 8 ) 2 ,H 2 S0 4 , is official (Ilyas- 
cyamince Sulphas, U. S. P.). It is yeliowish-white. 

Ladenburg also finds in henbane some hyoscine, a tropate of 
another alkaloid homologous with tropine. 

The alkaloids which occur in Daturia Stramonium, or Thornapple 
(Stramonii -Folia et Semen, U. S. P. ; Dhatura ; Datura alba; Da- 
tura? Folia et Semina, P. I.) and in Duboisia myoporoides, and for- 
merly supposed to be distinct alkaloids, called respectively Daturine 
and Duboisine, are identical with hyoscyamine, and the latter is 
isomeric, if not identical, with atropine (Ladenburg). Duboisine 
may, however, be identical with hyoscyine. Bees which sip from 
the flowers of stramonium are said to produce poisonous honey. 

Hyoscyamine melts when heated to between 108° and 109° C., and 
then is soon converted into atropine. Its solutions in alcohol or 
ether are stable, but the presence of a very minute amount of fixed 
caustic alkali, or a very little alkaline carbonate, causes complete con- 
version of the hyoscyamine into atropine. With chloride of gold its 
salts give a yellow crystalline precipitate. 

Jervine, or Jervia (C 30 H 46 N 2 O 3 ), occurs in Veratrum album, 
"White Hellebore, and V. viride (U. S. P.),* American White Hel- 
lebore, the root of which is officially recognized in Great Britain 
( Veratri Viridis Radix, B. P.). Its salts are much less soluble in 
water than those of veratrine. According to Bullock, Veratrum 
viride contains still another alkaloid, veratroidine ; and, according 
to Mitchell, Veratrum album also contains an alkaloid which he terms 
veratralbine. Tobien gives the formula of jervine as C 27 II 47 N 2 8 , and 
of veratroidine as C 51 H 78 N 2 16 or C 24 H 37 N0 7 . According to Wright, 
Veratrum album contains jervine, C 26 H 37 N0 3 ; pseudojervine, 2!) II 4 . r 
N0 7 ; rubijervine, C 26 H 43 N0 2 ; veratralbine, C 28 H 43 N0 5 ; and traces 
of veratrine, C 37 H 63 NO n . The same author finds Veratrum viride to 
contain jervine, pseudojervine, cevadine, C 32 H 49 N0 9 , rubijervine, and 
traces of veratrine and veratralbine. 

Juglandine is the name given by Tanret to an alkaloidal sub- 
stance obtained from the leaves of the walnut, Juglans regia. Tn 
the root-bark of Juglans cinerea, or Butternut {Juglans, U. S. P.), 
Thiebaud found a bitter substance and an acid resembling chryso- 
phanic. 

Lobeline, or Lobelia. — A volatile fluid alkaloid first isolated from 
the dried flowering herb Lobelia injlala (Lobelia, U. S. P.) by Proc- 
ter. In the pure state it is inodorous; impure, it smells slightly oi' 



*"The name Green Hellebore is sometimes applied to the drug, but it 
properly belongs to Helleborus vwidis (p. 495), which is medicinal in 
some purls of Europe." — Hanbury. 



526 THE ALKALOIDS. 

the plant, but mixed with ammonia it emits a strong and charac- 
teristic smell of the herb. With acids it forms crystalline salts. A 
solid alkaloid is said to be present also. 

Lupuline is stated by Greismayer to be a liquid volatile alkaloid 
contained in hops {Humulus lupulus). 

Nectaxdrixe. — Vide Beberixe. 

NicoTixE, Nicotixa, Nicotia, or Nicotylia, formula C 10 II U N 2 , or 
{^^i) /// '2^"i; This is also a volatile liquid alkaloid, forming the 
active principle of tobacco {Nicotiana tabacum), malate and citrate 
of nicotine being the forms in which it occurs in the leaf (Tabacum, 
U. S. P.). Its odor is characteristic : like coniine, it yields a precip- 
itate with perchloride of gold ; but, unlike that alkaloid, its aqueous 
solutions are precipitated yellowish-white by perchloride of plati- 
num. It is not official. It is also contained in pituri, a drug 
u chewed by the natives of some parts of Australia as a stimulant 
narcotic." 

Physostigmine, or Physostigma (C 15 II 21 N 3 2 ). — An alkaloid con- 
tained in the Calabar bean (Physostigma, U. S. P.), the seed of 
Physostigma venenosum (Jobst and Hesse). A trace of it power- 
fully contracts the pupil of the eye ; a small quantity is highly 
poisonous. Fraser also isolated another (but, possibly, the same) 
principle, and termed it Eserine, from Esere, the name of this ordeal- 
poison at Calabar. Salicylate of Physostigmine is official (Physostig- 
mincB Salicylas, U. S. P.), C 15 H 21 N 3 2 ,C-H 6 3 . Eber states that 
physostigmine by action of acids, etc. takes up the elements of 
water and becomes eseridine, C 15 H 23 N 3 3 , an alkaloid one-sixth the 
strength of physostigmine and occurring to some extent in the Cala- 
bar bean itself. 

Pilocarpine is, apparently, the active principle of the diapho- 
retic and sialogogue Jaborandi ', the leaflets of Pilocarpus pinnati- 
folius (Pilocarpus, U. S. P.). The occurrence of an alkaloid in this 
plant was first announced by Hardy, followed almost immediately 
by TSyasson. A crystalline nitrate and hydrochlorate were first 
obtained by Gerrard. The leaves also yield an essential oil, a ter- 
pene C 10 H 16 (Hardy). Harnack and Meyer state that the true form- 
ula for pilocarpine is C u H 16 N 2 2 , and that its effects resemble those 
of nicotine, but that it readily yields another alkaloid, jaborine, 
which probably closely approaches pilocarpine in composition, but is 
allied to atropine in effects. One salt is official (Pilocaipince Hydro- 
cJiloras, C n H 16 N 2 2 ,HCl, U. S. P.). The alkaloid is obtained from 
extract of jaborandi by shaking it with chloroform and a little 
alkali and evaporating the chloroformic solution. The product, neu- 
tralized by nitric acid and purified by recrystallization, yields the 
nitrate as a white granular powder or as prismatic crystals. It has 
a faint bitter taste, and is soluble in water and rectified spirit. 
Strong sulphuric acid forms with it a yellowish solution, which, on 
the addition of red chromate of potassium, gradually acquires an 
emerald-green color. It leaves no ash when burned with free access 
of air. It causes contraction of the pupil of the eye. Merck states 



PIPERINE — SPARTEINE. 527 

that a third alkaloid, pilocarpidine, C 10 H 14 N 2 O 2 , is present in jabo- 
randi. Harnack thinks that pilocarpine is probably a methyl-deri- 
vative of pilocarpidine. The suggestion also is offered that the form- 
ula for nicotine differing only by 2 from pilocarpidine, the latter is, 
perhaps, only dihydroxylnicotine. According to Merck, confirmed 
by Hardy and Calmels, jaborine is derived from pilocarpine by nat- 
ural oxidation, while pilocarpidine similarly yields jaboridine, C 10 - 
H 12 N 2 3 . The latter chemists have obtained pilocarpine artificially, 
/3-pyridine-a-laetic acid being converted into pilocarpidine, and this 
into pilocarpine. 

Piperine, or Piperia (Piperina, U. S. P.) (C 17 H 19 N0 3 ), is a feeble 
alkaloid occurring in white, black (Piper Nigrum, U. S. P. ) long 
pepper (Chavica officinarum, Mign.), and cubeb pepper (Cubeba, 
U. S. P.), associated with volatile oil and resin ; to these three sub- 
stances the odor, flavor, and acridity belong. Piperine is obtained 
on boiling white pepper with alcohol, and evaporating the liquid 
with solution of potash, which retains resin. Recrystallized from 
alcohol, piperine forms colorless prisms fusible at 212°. With acids 
and certain metallic compounds it forms salts, and distilled with 
strong alkali yields piperidine or piperidia (C 5 H 10 HN), an alkaloid 
of strong chemical properties, and piperic acid (C 12 H 10 O 4 ). Piperi- 
dine is interesting as being one of the alkaloids that have been 
obtained artificially by Ladenburg. It is hexa-hydro-pyridine, and 
is obtained by the action of nascent hydrogen on pyridine. John- 
stone finds it in long pepper and in ordinary pepper, more especially 
in the husk. According to Buckheim, the amorphous resin of the 
peppers is similar in constitution to piperine, alkalies breaking it up 
into piperidine and cavicic acid. Pyrethrin is also said to be a 
member of the series. The piperine of cubeb pepper is not to be 
confounded with cubebin, a neutral constituent having the formula 
C 10 H 10 O 3 , and probably a derivative of pyrocatechin. 

Sanguinarine, or Sanguinarina, is a colorless alkaloid obtained 
from the rhizome of Sanguinaria canadensis (Sanguinaria, U. S. P.), 
or Blood-root. Its salts have a red, crimson, or scarlet color. It 
appears to be identical with Chelerythrin. 

Solanine, or Solania (C 43 H 70 NO 16 ). — An alkaloid said to exist in 
the Woody Nightshade or Bitter-sweet (Solanum dulcamara). The 
dried young branches of the plant are official (Dulcamara, U. S. P.). 
It occurs also in the shoots, and in minute amount in the skins of 
the tubers, of the potato (Solanum tuberosum). The alkaloid is only 
slightly soluble in water, alcohol, or ether ; nitric acid colors it yel- 
low ; sulphuric acid produces at first a yellow, then a violet, and 
finally a brown coloration. It is said to be a conjugated compound 
of sugar with solanidine (C 25 H 89 NO). Geissler finds dulcamarin 
(C 22 II 34 O 10 ), a glucoside, to be the bitter constituent of Solatium 
dulcamara. A mixture of sulphuric acid and alcohol, or either 
selenic acid or sclcnate of sodium, and sulphuric acid, colors sola- 
nine or solanidine a dark red. 

Sparteine, or Sparteia (C 15 H 86 N), is a poisonous volatile alkaloid 



528 THE ALKALOIDS. 

occurring in broom-tops (Scoparius, U. S. P.). Its discoverer, Sten- 
house, considers that the diuretic principle of broom is scoparin, a 
non-poisonous body, sparingly soluble in cold water. Mills has 
obtained ethyl-sparteine (C 15 H 25 C 2 H 5 N) and diethyl-sparteine (C 15 H 24 - 
C 2 H 5 C 2 H 5 N). 

Spigelina. — According to Dudley, this is a volatile alkaloid and 
active principle of Spigelia marilandica, or Pink-root {Spigelia, 
U. S. P.), a vermifuge and depressant. 

Stillingine. — Bichy states that this alkaloid is present in Stil- 
lingia sylvatica or Queen's Root. 

Theine, Theia, or Caffeine (C 8 H 10 N 4 O 2 -f H 2 0).— This alkaloid 
{Caffeina, U. S. P.) occurs in tea, 2 to 4^ per cent., coffee, 11.2 per 
cent., Mate or Paraguay tea, .2 to 2 per cent., guarana (Guarana, 
U. S. P., "a dried paste prepared from the crushed or ground seeds 
of Paullinia sorbilis "), 5 per cent, and the kola-nut. Infusions 
and preparations of these vegetable products are used, chiefly as 
beverages, by three-fourths of the human race. It is remarkable 
that the instinct of man, even in his savage state, should have led 
him to select, as the bases of common beverages, just the four or 
five plants which out of many thousands are the only ones, so far as 
we know, containing theine. Theine is volatile. Considerable quan- 
tities may be collected by condensing the vapors evolved during the 
roasting of coffee on the large scale. The infusion of tea, from 
which astringent and coloring matters have been precipitated by 
solution of subacetate of lead, and which has been evaporated to a 
small bulk, yields a precipitate of theine on the addition of a strong 
solution of carbonate of potassium. It may be crystallized from 
alcohol or by sublimation. Theine forms salts with the stronger 
acids; they are decomposed by water. 

Test. — Concentrated nitric acid, or, better, a mixture of chlorate 
of potassium and hydrochloric acid, rapidly oxidizes theine, forming 
compounds which with ammonia yield a beautiful purple-red color, 
resembling the murexid obtained under similar circumstances from 
uric acid ; the oxidation must not be carried too far. Theine boiled 
with caustic potash yields methylamine (CH 3 HHN), the vapor of 
which has a peculiar characteristic odor. 

The chemical action of theine on the system is not yet quite made 
out. It is probably a pure stimulant. 

Theobromia, or Theobromine (C 7 H 8 N 4 2 ), is an alkaloid occurring 
in Cocoa, the seed of Thcobroma Cacao, to the extent of 1 to 2 per 
cent. According to Schmidt, a little theine is present also, espe- 
cially in the husks of the seed. Theine is methyl-theobromine, 
C 7 H 7 (CH 3 )N 4 2 . Both theine and theobromine are methyl-deriva- 
tives of xanthine, theobromine being dimethylxanthine (? the " theo- 
phylline" found in tea by Kossel). 

Trigonelline, C 7 H 7 N0 2 H 2 0. — Jahns states that this alkaloid, as 
well as one identical with choline, is present in the seeds of Fenu- 
greek, or Fenugreek, Trigonella, Foznum Grozcum, much used in vet- 



VERATRINE. 529 

erinary medicine and in some varieties of cattle-food and curry- 
powder. 

Yeratrine, or Veratria ( Veratrina, U. S. P.) (C 32 H 50 NO !) , Schmidt 
and Koppen ; C 52 H 86 N 2 15 , Weigelin). — This alkaloid occurs in Ceva- 
dilla (Sabadilla, B. P. ; the seeds of Asagrea officinalis, Lindley, 
termed Sabadilla officinarium by Brandt, and Veratrum officinale by 
Schlecht). It is also said to occur in the leaves of Sarracenia pur- 
purea. According to Weigelin, Cevadilla contains two isomeric 
varieties of veratrine, the one soluble, the other insoluble, in water. 
There are also present Sabadilline (C 41 II 66 N 2 13 ) and Sabatrine 
(C 51 H 8fi N 2 17 ). The veratrine of trade contains the two latter alka- 
loids (Weigelin). A mere trace of veratrine brought into contact 
with the mucous membrane of the nose causes violent fits of sneez- 
ing. These alkaloids, and those from the different species of Vera- 
trum, are evidently very closely allied. Wright and Luff, by the 
use of tartaric acid, a solvent less likely than the strong acids to 
decompose alkaloids, extract from Cevadilla, Veratrine, C3 7 H 53 NO n ; 
Cevadine, C 32 H 49 N0 9 ; and Cevadilline, C 34 H 53 N0 8 . 

The official process for the preparation of the alkaloid ( Veratria, 
B. P.) consists in exhausting the disintegrated cevadilla-seeds by 
alcohol, recovering most of the spirit by distillation, pouring the 
residue into water, by which much resin is precipitated, filtering, 
and precipitating the veratrine from the aqueous solution by am- 
monia. It is purified by washing with water, solution in dilute 
hydrochloric acid, decolorization of the liquid by animal charcoal, 
reprecipitation by ammonia, washing, and drying. The U. S. P. 
(1870) process is similar, but includes treatment of the first crude 
veratrine by diluted sulphuric acid and precipitation of alkaloid by 
magnesia. 

Unguentum Veratrince, U. S. P., contains 4 per cent, of the 
alkaloid. 

QUESTIONS AND EXERCISES. 

842. How is Aconitine prepared? 

843. Give the strength of the official preparations of Atropine. 

844. Describe the properties of atropine. 

845. What is the active principle of Stramonium? 

846. ^ Mention pharmacopoeial substances containing beberine and 
berberine respectively. 

847. Give the characters of beberine. 

848. In what does nectandrine differ from beberine ? 

849. Mention the characteristics of coniine. 

850. What is the active principle of Ipecacuanha? 

851. Name the alkaloid of Tobacco. 

852. Give the name and properties of the active principle of Cala- 
bar Bean. 

853. What are the sources of piperine ? 

854. Whence is theine obtained ? 

855. Describe the preparations of veratrine. 
85G. State the properties of veratrine. 



530 ORGANIC CHEMISTRY. 

PROXIMATE CONSTITUENTS OF THE ANIMAL 
ORGANISM. 

Proteid Principles or Albumenoids. 

Albumen. — Agitate, thoroughly, white of egg (Ovi Albumen, 
B. P.) with water, and strain or pour off the liquid from the 
flocculent membranous insoluble matter. One white in 100 
c.c. of water forms the " Test-Solution of Albumen," U. S. P. 

Test. — Heat a portion of this solution of albumen to the 
boiling-point ; the albumen becomes insoluble, separating in 
clots or coagula of characteristic appearance. 

Other Reactions. — Add to small quantities of aqueous solu- 
tion of albumen solutions of corrosive sublimate, nitrate of 
silver, sulphate of copper, acetate of lead, alum, perchloride 
of tin ; the various salts not only coagulate, but form insol- 
uble compounds with albumen. Hence the value of an egg 
as a temporary antidote in cases of poisoning by many metal- 
lic salts, its administration retarding the absorption of the 
poison until the stomach-pump or other means cam be applied. 
Sulphuric, nitric, and hydrochloric acids precipitate albumen ; 
the coagulum is slowly redissoived by aid of heat, a brown, 
yellow, or purplish-red color being produced. Neither acetic, 
tartaric, nor organic acids generally, except picric and gallo- 
tannic, coagulate albumen. Alkalies prevent the precipitation 
of albumen. 

Yolk or Yelk of Egg ( Yitellus, U. S. P.) contains only 3 per cent, 
of albumen — the white 12 J. The yolk also contains 30 per cent, of 
yellow fat and 14 of casein. 

Albumen is met with in large quantity in the serum of blood, in 
smaller quantity in chyle and lymph, and in the brain, kidneys, 
liver, muscles, and pancreas. It is not a normal constituent of 
saliva, gastric juice, bile, or mucus, but occurs in those secretions 
during inflammation. It is found in the urine and feces only under 
certain diseased states of the system. 

The cause of the coagulation of albumen by heat has not yet been 
discovered. 

Albumen has never been obtained sufficiently pure to admit of its 
composition being expressed by a trustworthy formula ; Gerhardt 
regarded it as a sodium compound (HN"aC 72 H n0 N I8 SO 22 ,H 2 O). 

Egg-albumen, and, to some extent, blood-albumen, is largely used 
by calico-printers as a vehicle for colors, serving also, when dry, as 
a glaze. Curriers prize egg-oil for softening leather. 

Albumen coagulated by heat is said to be recoverable in a scarcely 
altered fluid condition by contact with a dilute aqueous solution of a 
very small proportion of pepsin. 



BLOOD — CASEIN. 



531 



Fibrin, Casein, Legumin. 

Fibrin is the chief constituent of the muscular tissue of animals. 
It occurs in solution in the blood ; and its spontaneous solidification 
or coagulation is the cause of the clotting of blood shortly after 
being drawn from the body — a phenomenon which cannot at pres- 
ent be explained satisfactorily. Fibrin may be obtained by whip- 
ping fresh blood with a bundle of twigs, separating the adherent 
fibres, and washing in water till colorless. It may be dried or kept 
under spirit of wine. 



Average Composition of Blood (in 1000 parts). 
(Compiled by Kirkes.) 

Water 784 

Albumen 70 

Fibrin 2.2 

Red corpuscles (globulin, 123 ; hsematin, 7) . . 130 

Cholesterin . 0.08 " 

Cerebrin 0.40 

Serolin 0.02 . 

Oleic and margaric acids ..... 
Volatile and odorous fatty acid . . 
Fat containing phosphorus .... 

Chloride of sodium . „ , 3.6 

Chloride of potassium .35 

Phosphate of sodium (Na 3 P0 4 ) .2 

Carbonate of sodium .82 

Sulphate of sodium .28 

Phosphates of calcium and magnesium .... .25 

Oxide and phosphate of iron .50 

Extractive matters, biliary coloring-matter, gases, 

and accidental substances 6.4 

ioooT 



Percentage Proportion of the Chief Constituents of Blood. 

Water 78.4 

Red corpuscles (solid residue) 13.0 

Albumen of serum 7.0 

Inorganic salts .603 

Extractive, fatty, and other matters . . .777 
Fibrin 22 

10O 

Casein occurs in cow's milk (Lac, B. P.) to the extent of about 4 
per cent., dissolved by a trace of alkaline salt. Its solution does not 
spontaneously coagulate, like that of fibrin, nor by heat like albu- 
men; but acids cause its precipitation from milk in the form of a 
curd (cheese) containing the fat- (butter-) globules previously sus- 
pended in the milk, a clear yellow liquid (or whey) remaining. 



532 



ORGANIC CHEMISTRY. 



Cards and u-liey are also produced on adding to milk a piece or an 
infusion of rennet, the salted and dried inner membrane of the fourth 
stomach of the calf. The exact action of rennet is not known, but 
it seems to be due to the presence of a milk-curdling ferment which 
is not an acid and not pepsin, and which appears also to occur in 
the pancreatic juice, the intestinal juice, and some vegetable juices. 
Respecting rennet Soxhlet says : " 60 to 80 grammes of calf s stom- 
ach steeped for five days in 1 litre of a 5 per cent, solution of com- 
mon salt at ordinary temperatures yield a solution of which 1 vol. 
will coagulate 10,000 vols, of new milk at a temperature of 95° F. 
in forty minutes. If the filtered solution is treated with 60 to 90 
grammes more of stomach, a solution of double strength is obtained ; 
another repetition gives a solution three times the strength of the 
original one. To prevent decomposition, about 0.3 per cent, of thy- 
mol may be added to the concentrated rennet extract solution. Pos- 
sibly a slight taste due to this may be detected in the finest cheese, 
but for the same reason oil of cloves is much more objectionable. 
Boric acid is on all accounts the best antiseptic to employ, and solu- 
tions to which it has been added may be kept in covered vessels for 
months. All extract solutions lose strength on keeping ; during the 
first two months the solution may become 30 per cent, weaker, then 
the strength remains nearly constant for eight months in the case of 
a solution of 1 in 18,000. Alcohol is almost as good an antiseptic 
as boric acid if the solution be preserved in well- stoppered flasks." 



A 


verage Composition of 1000 parts 


of MUk. 






Specific 
gravity. 


Water, constit- 
uents. 


Casein 

and ex- Sugar, 
tractive. , 


Butter. 


Salts. 


Woman . 
; Cow . . 


f 1.030- { 
| 1.034 j 
/ 1.030-1 
i 1.035 ) 


870 130 
877 123 


27 

40 


60 
46 


40 
30 


3 

7 



Leeds puts the average composition of human milk at 2 per cent, 
of albumenoids, 7 per cent, of milk-sugar, 4 per cent, of fat, and 0.2 
per cent, of ash. 

Specific gravity alone, as taken by the form of hydrometer termed 
a bj'-U, meter, or even by more delicate means, is of little value as an 
indication of the richness of milk, the butter and the other solids 
exerting an influence in opposite directions. Good cow's milk 
affords from 10 to 12 per cent, by volume of cream and 3 to 3J 
per cent, of butter. The water of milk seldom varies more than 
from 87 to 88 per cent., and the solid constituents from 13 to 12. 
Indeed, excluding its butter, milk is curiously regular in composi- 
tion. The non-fatty solids in the mixed milk of a herd or dairy of 
healthy cows is almost a constant quantity — namely. 9.3 per cent. 
A lower proportion of non-fatty solids in a sample of milk points to 
the addition of water. Thus, supposing that 100 grains of a speci- 



MILK. 533 

men of milk evaporated to dryness, and all butter extracted from 
the residue by ether, yielded a non-fatty residue of 7.44 grains, the 
specimen would probably be four-fifths milk and one-fifth water. 
For if 9.3 indicate 100, then 7.44 indicate 80. Occasionally, under 
exceptional circumstances, a sample of genuine milk might be 
slightly poorer than that from a healthy herd, and therefore, for 
legal purposes, a standard of 9 per cent, by weight of non-fatty 
solids and 2.5 per cent, of butter-fat has been proposed. Only in 
the rare cases of milk containing an unusually large proportion of 
butter-fat would any milk yielding less than 9 per cent, of non-fatty 
solids be regarded as genuine. And, again, no milk would be con- 
sidered genuine, under this standard, if it yielded less than 2.5 per 
cent, of fat, not even in the rare case of its containing an unusually 
large proportion of real non-fatty milk-solids. Half-starved cows 
might yield milk below these standards, but it could scarcely be 
considered to be normal or better fitted for food than milk watered 
after leaving the cow. If, however, such milk is to be regarded 
as genuine, the standard of 8.5 of non-fatty solids will not be too 
low. 

Ewe's milk is much richer than either human or cow's milk. 

Under the microscope milk is seen to consist of minute corpuscles 
floating in a transparent medium. These corpuscles consist of the 
fatty matter (butter), said to be contained in a filmy albumenoid 
envelope. The fat is fluid at the normal temperature of the ani- 
mal, and remains so until the milk is well agitated by churning or 
otherwise or until the milk is frozen. 

Legumin or vegetable casein is found in most leguminous seeds, 
such as sweet and bitter almonds. Peas contain about 25 per cent, 
of legumin. 

Vegetable albumen is contained in many plant-juices, and is 
deposited in flocculi on heating such liquids. Vegetable fibrin is 
the name given by Liebig and Dumas to that portion of the gluten 
of wheat which is insoluble in alcohol and ether. Spongine, the 
organic matter of sponge, appears to be a proteid. 

Albumenoid substances are nearly identical in percentage composi- 
tion. Albumen and fibrin contain 53.5 of carbon, 7 of hydrogen, 1 5.5 
of nitrogen, 22 of oxygen, 1.6 of sulphur, and .4 of phosphorus. Casein 
contains no phosphorus. These three bodies are often termed the 
plastic elements of nutrition, under the assumption that animals 
directly assimilate them in forming muscles, nerves, and other 
tissues, — starch, sugar, and similar matter forming the respiratory 
materials of food, because more immediately concerned in keeping 
up the temperature of the body by the combustion going on between 
them and their products and the oxygen of the air in the blood. 

The whole of the organic nitrogen in food must not, however, be 
regarded as representing true albumenoids, some existing as amidic 
and similar compounds, bodies having a simplicity of composition 
characteristic of the products of physiological action on i'ood. rather 
than that complexity of composition characteristic of true nutrients. 
Albumenoids in decomposing yield much fatty as well as other sub- 
stances. Possibly a portion, at least, of the qdipocere (adeps, fat j 
45* 



534 ORGANIC CHEMISTRY. 

cera, wax), or corpse-fat, characteristic of the remains of buried 
animals is thus derived. 

Musk (Moschus, B. P.), " the dried secretion from the preputial 
follicles of Moschus moschiferns" 1 (the musk-deer), is a mixture of 
albumenoid, fatty, and other animal matters with a volatile odorous 
substance of unknown composition. 



Gelatigenous Substances. 

These nitrogenous bodies differ, chemically, from the albumenoids 
in containing less carbon and sulphur and more nitrogen. They are 
contained in certain animal tissues, and on boiling with water yield 
a solution which has the remarkable property of solidifying to a jelly 
on cooling. The tendons, ligaments, bone, skin, and serous mem- 
branes afford gelatin proper ; the cartilages give chondrine, which 
differs from gelatin in composition and in being precipitated by veg- 
etable acids, alum, and the acetates of lead. The purest source of 
gelatin is isinglass (B. P.) (Ichthijocolla, U. S. P.), "the swimming 
bladder or sound of various species of Acipenser, Linn., prepared 
and cut in fine shreds. " Small quantities are more easily disinte- 
grated by a file than a knife. Fifty grains dissolved in 5 ounces of 
distilled water forms the official " Solution of Isinglass," B. P. Glue 
is an impure variety of gelatin, made from the trimmings of hides ; 
size is glue of inferior tenacity, prepared from the parings of parch- 
ment and thin skins. " Among the varieties of gelatin derived from 
different tissues and from the same sources at different ages, much 
diversity exists as to the firmness and other characters of the solid 
formed on the cooling of the solutions. The differences between 
isinglass, size, and glue in these respects are familiarly known, and 
afford good examples of the varieties called weak and strong or low 
and high gelatins. The differences are sometimes ascribed to the 
quantities of water combined in each case with the pure or anhy- 
drous gelatin, part of which water seems to be intimately united with 
the gelatin ; for no artificial addition of water to glue would give it 
the character of size, nor would any abstraction of water from isin- 
glass or size convert it into the hard, dry substance of glue. But 
such a change is effected in the gradual process of nutrition of the 
tissues ; for, as a general rule, the tissues of an old animal yield a 
much firmer or stronger jelly than the corresponding parts of a 
young animal of the same species" (Kirke's Physiology). 

Gelatin is supposed by some to be a glucoside, yielding an am- 
monium salt when boiled with diluted acids. It appears to unite 
chemically with a portion of the water in which it is soaked when 
used for culinary or manufacturing purposes, for a solution of glue 
in hot anhydrous glycerin does not yield an ordinary jelly on cool- 
ing. From its solution in water gelatin is precipitated by alcohol, 
corrosive sublimate, perchloride of platinum, and by tannic acid. Its 
aqueous solution is not, like that of albumen, coagulated by heat 
nor is it precipitated by acids. By prolonged ebullition its gelatin^ 
izing power is destroyed. 



535 



Pepsin. 



Pepsin (from tvettto, pepto, I digest) is a nitrogenous substance 
existing in the gastric juice and as a viscid matter in the peptic 
glands and on the walls of the stomachs of animals. It appears to 
be a modification of a precursor termed propepsin, stomachs not 
yielding as much pepsin when fresh as after twenty-four hours. To iso- 
late the pepsin the cleansed mucous membrane of the stomach (of the 
hog, sheep, or calf, killed fasting) is scraped, and macerated, with 
the scrapings, in cold water for twelve hours ; the pepsin in the 
strained liquid is then precipitated by acetate of lead, the deposit 
washed once or twice by decantation, sulphuretted hydrogen passed 
through the mixture of the deposit with a little water to remove the 
whole of the lead, and the filtered liquid evaporated to dryness at a 
temperature not exceeding 105° F. Pepsin is a powerful promoter of 
digestion ; its solution is hence frequently termed artificial gastric 
juice. As met with in pharmacy its strength varies greatly. It is 
often prepared by simply mixing with starch the thick liquid 
obtained on macerating the scraped stomach with water, and evapo- 
rating to dryness. ( Vide Pharmaceutical Journal, 1865—66, p. 112, 
and 1871-72, pp. 785 and 843.) The English official process (Pepsin, 
B. P.) simply consists in scraping the viscid pulp from the slightly 
washed inner surface of the stomach, and quickly evaporating it to 
dryness on glass or glazed earthenware at a temperature not exceed- 
ing 100° F. The product is powdered. U A light yellowish-brown 
powder, having a faint but not disagreeable odor and a slightly 
saline taste, without any indication of putrescence. Very little solu- 
ble in water or spirit. Two grains of it, with an ounce of distilled 
water, to -which 5 minims of hydrochloric acid have been added, 
form a mixture in which at least 100 grains of hard-boiled white of 
egg, passed through wire gauze of 36 meshes per linear inch and 
made of No. 32 brass or copper wire, will dissolve on their being 
well mixed, digested, and well stirred together for thirty minutes at 
a temperature of 130° F. (54.4° C.)." The solvent or digestive action 
of pepsin on the albumenoids, etc. in the stomach results in a nutri- 
tive and digestive fluid termed peptone, forming a portion of the 
whole product of stomach-digestion or chyme. It is thus that such 
food is prepared for conversion into blood. Artificial or alimentary 
peptone may be made by digesting blood-fibrin with pepsin in very 
weak hydrochloric acid. Clermont prepares alimentary peptone in 
solution by heating 40 parts of minced meat with 30 of water and 1 
of sulphuric acid in a sealed tube ; filtering the resulting fluid, 
evaporating to dryness, and treating the residue with water. The 
solution is not prccipitable by hydrochloric, nitric, or acetic arid ; 
when diluted with strong, 90 per cent, alcohol it gives an abundant 
precipitate, and is precipitated by tannin, mercuric chloride, and 
platinic chloride. Peptone is not readily coagulated by heat, and 
it freely diffuses through membranes. It appears to be isomeric 
with albumen. Propeptone, parapeptone, or hemialbumose is a mix- 
ture of substances intermediate between albumen and peptone. It 
readily diffuses through membranes. Some vegetables, notably the 



536 ORGANIC CHEMISTRY. 

leaves of the papaw tree, Carica papaya, appear to contain a prin- 
ciple, "papaine," analogous in properties to pepsin. According to 
Wurtz, papaine is an albumenoid. 

The preparation official in the United States is Pepsinum Saccha- 
ratum: "1 part of Saccharated Pepsin, dissolved in 500 parts of 
water acidulated with 7.5 parts of hydrochloric acid, should digest 
at least 50 parts of hard-boiled egg-albumen in five or six hours at 
a temperature of 38° to 40° C. (100° to 104° F.)." 

Liquor Pepsini, U. S. P., is a mixture of 40 parts of saccharated 
pepsin, 12 of hydrochloric acid, 400 of glycerin, and water to make 
1000. It should not develop an ammoniacal odor on keeping (abs. 
of mucus). 

(For a resume of the different modes of preparing pepsin, see an 
article by Petit in the Pharmaceutical Journal for July 17, 1880.) 

Pancreatin. 

The pancreas (or "sweetbread") secretes a colorless fluid which 
contains 1J to 2h per cent, of an albumenoid substance which has 
the power of converting starch into sugar, and especially of emulsi- 
fying fat. It may be precipitated by chloride of sodium from an 
acidulated infusion of the pancreas. Stutzer prepares a powerful 
extract by digesting the pancreas in lime-water and glycerin with free 
exposure to air. It is soluble in cold water. An extremely small 
proportion emulsifies a large volume of fat. The pancreatic juice 
would seem to contain four distinct ferments — namely, the emulsify- 
ing principle, the milk-curdling ferment, pancreatic diastase, and a 
pepsin-like substance termed trypsin, which, unlike pepsin, attacks 
albumenoids in neutral or even slightly alkaline fluids. 

Bile. 

Bile (Fel Bovis, U. S. P.) is officially the gall of the ox (Bos tau- 
rus, Linn.) either heated to 80° C, strained, and evaporated from 100 
parts to 15 {Fel Bovis Inspissatum, U. S. P.), or freed from mucus 
by agitating with alcohol (in which mucus is insoluble), filtering, 
and evaporating. The latter is the official Purified Ox-Bile {Fel 
Bovis Purifcatum, U. S. P.); it has a resinous appearance, but is 
chiefly composed of two crystalline substances having the constitu- 
tion of a soap ; the one is termed taurocholate of sodium (NaC 26 H 42 - 
N0 6 S), the other is glycocholate, or simply cholate, of sodium (NaC 26 - 
H 44 N0 7 ). Both taurocholates and glycocholates are conjugate bodies 
readily yielding, the former cholic or cholalic acid (HC 24 H 29 5 ) and 
taurine (C 2 H 7 N0 3 S), the latter cholalic acid and glycocine or glycocoll 
(C 2 H 5 N0 2 ), a soluble crystalline body having interesting physiologi- 
cal relations, inasmuch as it is obtainable from gelatin (hence the 
name glycocoll or sugar of gelatin, from y?ivxvc, glucus, sweet, and 
K6M.a,kolla, glue) and from hippuric acid. Choline is an alkaloid 
originally found in bile, hence its name {x'^Vi chole, bile), but it 
occurs also in the substance of the brain, etc., and in plants — ergot, 
Indian hemp, ipecacuanha, etc. 



QUESTIONS AND EXERCISES. 537 

Tests for Bile. — The presence of bile in a liquid, such as 
urine, may be detected by the following tests : The fluid is 
gradually mixed with half its bulk of strong sulphuric acid in 
a test-tube, rise of temperature being prevented by partial 
immersion of the tube in water. A small quantity of pow- 
dered white sugar is then introduced and well mixed with the 
acid liquid, and more sulphuric acid then poured in ; as the 
temperature rises a reddish or violet coloration is produced. 
The cholalic acid liberated in the reaction furnishes the color. 
This is Pcttenkofer's test. It is somewhat interfered with by 
albumen and volatile oils. Quinlan tests for bile by placing a 
three-millimetre stratum of the suspected fluid before the slit 
of the spectroscope, and observing the absorption which 
extends, according to the amount present, from the violet spec- 
trum as far as the Fraunhbfer line D. 



QUESTIONS AND EXERCISES. 

857. In what form is albumen familiar? 

858. Name the chief tests for albumen. 

859. Why is the administration of albumen useful in cases of 
poisoning ? 

860. Mention the points of difference between yolk and white of 
egg. 

861. From what sources other than egg may albumen be ob- 
tained ? 

862. In what respects does fibrin differ from albumen ? 

863. Enumerate the chief constituents of blood. 

864. How may fibrin be obtained from blood? 

865. State the differences between casein, fibrin, and albu- 
men. 

866. What are the relations of cream, butter, curds and whey, and 
cheese to milk ? 

867. Describe the microscopic appearances of blood and of milk. 

868. How much cream should be obtained from good milk ? 

869. What is the percentage of water in genuine milk? 

870. Name the sources of vegetable albumen and vegetable 
casein. 

871. Give the percentage of nitrogen in albumenoid sub- 
stances. 

872. Describe the chemical nature of musk. 

873. In what He the peculiarities of gelatigenous substances? 

874. To what extent do isinglass, glue, and size differ? 

875. Whence is pepsin obtained, ami how prepared? 

876. Give the proximate constituents of bile. 

877. AVhat are the tests for bile? 



538 COLORING MATTERS. 



COLORING MATTERS. 

The animal, vegetable, and mineral kingdoms abound in sub- 
stances or pigments which powerfully decompose light, absorbing 
certain of its constituent colors and reflecting some others. Thus, 
for example, most leaves contain a body termed chlorophyl, which 
has the power of absorbing red light and reflecting green ; these 
reflected rays, entering the eye of an observer and striking on the 
retina (the expanded extremity of the optic nerve), always communi- 
cate the same impression to the brain ; in popular language, the leaf 
is said to be green. Art has richly supplemented the number of 
such natural coloring-matters. 

Yellow. — 1. Chrome-yellow occurs in more than a dozen shades 
(see Lead, Chromate of). 2. Fustic or yellow-wood is the wood of 
the Rhus cotinus. 3. Gamboge (see Gamboge). 4. Ochre is met 
with of many tints, under the names of yellow ochre, gold yellow, 
gold earth or ochre, yellow sienna, Chinese yellow. It is chiefly a 
mixture of oxyhydrates of iron with alumina and lime. 5. Orpi- 
ment is a sulphide of arsenium (As 2 S 3 ). 6. Persian berries or Avi- 
gnon grains contain a yellow principle termed rhamnin and other 
crystalline bodies : they are the product of two or three species of 
Rhamnus. 7. Purree or Indian yellow is said by Stenhouse to owe 
its color to purrate or euxanthate of magnesium (MgC 42 H 34 22 ). 8. 
Quercitron is the bark of Quercus tinctoria : it contains the yellow 
giucoside quercitrin (C 18 H 18 O 10 H 2 O). 9. Rhubarb (see Chrysophanic 
Acid, p. 337). 10. Saffron (Crocus, B. P.), the dried stigma and part 
of the style of Crocus sativus, yields saffrauin or polychroite, an 
orange-red giucoside, which by the action of dilute acids and by 
other means breaks up as shown in the following equation, yield- 
ing red crocin (Weiss) : — 

C 48 H fi0 O 18 + H 2 = 2(C 16 H 18 6 ) + C 10 H 14 O + C 6 H 12 6 

Polychroite. W ater. Crocin. "S ol. oil of saffron. Sugar. 

Kayser, however, gives the formula of pure crocin as C 44 H 70 O 28 , and 
states that by absorption of water, 7H 2 0, it yields pure crocetin, 
C 34 II 46 9 , and sugar, 9C 6 H 12 6 . Any admixture of carbonate of 
calcium, sulphates of barium or calcium, or similar powder, with 
saffron, is readily detected on placing a little in a glass of warm 
water and stirring, when insoluble powder is deposited. " Ignited 
with free access of air, it should yield not more than 6 per cent, of 
ash ; ' (B. P.). 11. Turmeric, the rhizome of Curcuma longa, owes 
its yellow color to curcumin, a resin, the formula of which is said by 
Daube to be C 10 H 10 O 3 . and by Iwanof. C 16 H ]6 4 . Jackson and Menke 
state that curcumin is an acid, and that its formula is H 2 C 14 H ]2 4 . 
Possibly two yellow pigments are present. The coloring-matter of 
turmeric is readily dissolved by chloroform : not so those of saffron, 
mustard, or the best East Indian rhubarb, on which fact methods of 
detecting turmeric in those substances have been founded (Howie, 
Pharmaceutical Journal, November, 1, 1873). 12. Weld (Reseda 
Ivteola) contains a durable yellow matter termed luteolin (C 20 H 14 O 3 ). 
13. Picric or carbazotic acid (p. 448) is a very powerful yellow dye. 



RED. 539 

14. Dried and powdered carrots yield to bisulphide (ft" carbon a yel- 
low coloring-matter, u carrotin," which is obtained on evaporating 
the solvent. It is said to be used in coloring butter. 

Red. — 1. Alkanet, the root of Alkanna tinctoria, Tausch, Anchusa 
tinctoria, Desf., yields anchusin (C 35 H 40 O 8 ), a resinoid matter soluble 
in oils and fat. 2. Annatto, Arnatto, or Arnotto, a paste prepared 
by evaporating a strained aqueous extract of the seeds of Bixa orel- 
lana, contains bixin (C 28 H 34 5 ), an orange-red, and orellin, a yellow 
principle. 3. Brazil-wood (Ccesalpinia brasiliensis) furnishes bre- 
zilin, C 16 H H 5 , the basis of several lakes : Sapan-wood and Cam- 
wood probably contain the same substance. 4. Cinnabar, Chinese 
red, vermilion, or Paris red, is mercuric sulphide. 5. Chrome-red 
is an oxychromate of lead. 6. Cochineal (p. 334). 7. Madder, the 
root of Bubia tinctorum, powdered and treated with sulphuric acid 
and acidulated Avater to effect the removal of earthy and other inert 
matters, furnishes a residual powder termed garancin. Garancin 
yields to pure water alizarin (C u H 10 O 4 ,3H 2 O), the red, neutral, crys- 
tallizable coloring-matter of madder. Alizarin does not exist ready 
formed in the plant ; but is derived, by fermentation, from rubin, a 
yellowish resinoid substance. Alizarin is now produced artificially 
from anthracene, one of the solid constituents of coal-tar (see p. 435). 
8. Mulberry-juice {Mori Succus, B. P.) contains a violet-red coloring- 
matter which has not been chemically examined. 9. Bed lead (p. 
242). 10. Bed oxide of iron, of shades varying from light to brown 
red, is found native. The common names of it are Armenian bole, 
Berlin red, colcothar, English red, red ochre, burnt ochre, red earth, 
terra di sienna, mineral purple, stone red, and Indian red. 11. Bed 
Sanders-wood or Bed Sandal-ivood (Bterocarpi Lignum, B. P.), the 
billets and chips of Bterocarpus santalinus, owes its color to santa- 
lin (C H H ]2 4 ), a crystalline resinoid matter. Crystalline pterocarp/n, 
C 10 H 8 O 3 , and homopterocarpin, C 12 H 12 3 , are also present (Cazeneuve). 
12. Bed-Boppy Betals (B/ueados Betala, B. P.), from the Bapaver 
rhwas, contains a red coloring principle which has not yet been iso- 
lated in a state of purity. The author has sought for morphine in 
large quantities of the petals, but could not find a trace of that alka- 
loid. 13. Bed-Bose Betals (Bosob Gallicce Betala, B. P.), and those 
of the Cabbage-Rose (Bosce Centifolice Betala, B. P.), also yield a 
red substance which has not been analyzed. 14. Sajfiower, Dyer's 
Saffron, or Bastard Saffron, the florets of Carthamus tinctorius, 
contains an unimportant yellow dye, and 5 per cent, of carthamin 
(C 14 II 16 7 ), an uncrystallizable red dye, the pigment of the old pink 
saucers. Carthamin seems to possess acid characters, and (like si- 
licic acid and other substances) to be soluble in water for a certain 
time after liberation from its alkaline solution ; for fabrics are dyed 
with safflower by immersion in a bath made of an infusion in dilute 
alkali neutralized by citric acid immediately before use. the car- 
thamin probably penetrating the cells and vessels of the fibres in a 
soluble form, there becoming insoluble and imprisoned, and thus 
giving permanent color to the wool, silk, or other material. Mixed 
with French chalk, carthamin is used as a cosmetic under the name 



540 COLORING MATTERS. 

of vegetable rouge — carmine being animal rouge, and red oxide of 
iron the mineral rouge. 15. Lac-dye is a cheap form of cochineal, 
and is also yielded by the species of Coccus whose resinous excre- 
tion constitutes lac (stick-lac, seed-lac, or shell-lac, according to its 
condition as gathered off the twigs on which it is deposited, or as 
roughly separated from impurities in seed-like powder or lumps, or 
as melted and squeezed through bags into shell-like pieces). 16. 
Logwood (Hazmatoxyli Lignum, B. P.) contains a yellow substance, 
hematoxylin (C 16 H u 6 H 2 or 3H 2 0), to which any medicinal useful- 
ness of the wood is perhaps due, and which, under the influence of 
air and alkali or ferments, assumes an intense red color — hseniatein. 
Under the influence of ammonia and air hsematoxylin yields green- 
ish-violet iridescent scales of hoemate'in (C 16 H 12 6 3H 2 0). 17. Red 
enamel-coXoYs, for glass-staining and ceramic operations, are pro- 
duced either by cuprous silicate or purple of Cassius (p. 244). 

Blue. — 1. Cobalt oxide precipitated in combination or admixture 
with alumina or phosphate of calcium forms ThenaroVs blue, cobalt- 
blue, Hoffners blue, and cobaltic ultramarine. 2. Smalt, Saxony 
blue, or King's blue is rough cobalt glass in fine powder (p. 232)! 
3. Copper-blue, mountain blue, and English or Hambro? blue are 
carbonates or oxycarbonates of copper. 4. Indigo, C 16 H 10 N 2 O 2 (p. 
289). 5. Litmus, lichen-blue, turnsole, orchil or archil, and cudbear 
are products of the action of air and alkalies on certain colorless 
principles, as orcin (C 6 H 3 (OH) 2 CH 3 ), derived from different species 
of lichen — Roccella, Variolaria, and Lecanora. 6. Prussian blue 
(p. 240) and TurnbulVs blue (p. 241) are met with under the names 
of Erlangen, Louisa, Saxon, Paris, or Berlin blue. 7. Ultramarine, 
formerly obtained from the rare mineral lapis lazuli, is now cheaply 
made on a large scale by roasting a mixture of fine white clay, car- 
bonate of sodium, sulphur, and charcoal or rosin. Its constitution 
is not well made out. Acids decompose it, sulphuretted hydrogen 
escaping. 

Green. — 1. Cupro-arsenical green pigments (p. 175). 2. Chlo- 
rophyl, Leaf-green, or Chromule. A method of extracting chlo- 
rophyl is given under "Extracts-' (vide Index). It is resinoid, 
soluble in alcohol and ether, insoluble in water, and, according to 
Fremy and Schunk, consists of a blue substance, phyllocyanin 
(C 34 H 68 N 4 17 ?), and a yellow, phylloxantMn ; the yellow tints in 
fading autumnal leaves, Fremy says, are due to the latter principle, 
the former being the first to fade. Chlorophyl would probably well 
repay extended investigation, as it has never been obtained pure. 

3. Sap-, buckthorn-, vegetable-, or bladder-green is obtained by evap- 
orating to dryness a mixture of lime and the juice (Bhamni Succus, 
B. P.) of the berries of the Buckthorn (Rhamnus catharticus). It is 
soluble in water, slightly in alcohol, and insoluble in ether and oils. 

4. Green ultramarine is made by a process similar to that for blue 
ultramarine, 5. Mixtures of blue and yellow pigments and dyes 
are common sources of green colors. 6. Glass and earthenware 
are colored green by oxide of chromium and black oxide of 
copper. 



BROWN — BLACK — WHITE ; ETC. 541 

Brown. — 1. Umber, Sienna, or Chestnut-brown is found native. 
By heat it is darkened in tint, and is then known as burnt umber. 
It is a mixture of oxide of iron, silica, and alumina. 2. Sepia is a 
dried fluid from the ink-bag of cuttle-fishes (Sepiadce) ; by its ejec- 
tion into adjacent water the animal is said to obtain opportunity of 
escape from enemies. 3. Catechu (p. 358) furnishes a brown color- 
ing-matter. 

Black. — 1. Black-lead (p. 30), bone-black (p. 110), or ivory-black 
and lampblack, the latter a deposited soot from the incomplete com- 
bustion of resin and tar, are varieties of carbon. 2. Burnt sugar 
or caramel (p. 462). 3. Indian ink is usually a dried mixture of 
fine lampblack and size or thin glue. 4. Black ink is essentially 
tannates and gallates of iron suspended in water containing a little 
gum in solution. 5. Printer's ink is well-boiled linseed or other oil, 
mixed with good lampblack, vermilion, or other pigment. 6. Black 
dyes are of the same nature as ink. 7. The pigmentum nigrum of 
black feathers, such as those of the common rook, of dark hair, and 
probably also of the skin of the negro, seems to be due to the black 
substance which remains undissolved when black feathers are digested 
for some time in dilute sulphuric acid. It is said to have the formula 
C 18 H 16 N 2 8 (Hodgkinson and Sorby). 

White Pigments. — 1. Chalk or Whiting (p. 108). 2. French 
chalk, steatite, or soapstone, a silicate of magnesium. 3. Heavy 
White (p. 191). 4. Pearl-white (p. 250). 5. Plaster of Paris (p. 
103). 6. Starch (p. 463). 7. White Lead or Cremnitz White (p. 
208). 8. Zinc White or Chinese White (p. 132). 9. Constant 
White is tungstate of barium. 10. Flake White is basic nitrate 
of bismuth. 11. Oxides of tin and zinc and phosphate of calcium 
are employed for giving a white opacity to glass. 

Aniline Colors — Coal-tar colors. — Within the last ten years 
nearly every shade of color seen in the animal and vegetable king- 
doms has been successfully imitated by certain dyes and pigments 
primarily derived from a mineral, coal. Coal distilled for gas 
furnishes tar or gas-tar. Coal-tar contains some aniline, but especi- 
ally it contains a liquid convertible into aniline — namely, benzene 
(CgH 6 ), first discovered by Faraday in compressed oil-gas. From 
aniline, by oxidation, Runge ( obtained the violet-color reaction, the 
body producing which Perkin afterward studied and isolated, and 
manufactured under the name of mauve. Aniline-red (fuchsine, 
magenta, or roseanili7ie), aniline-yellow, aniline-green, aniline-blue, 
and, in short, aniline dyes, lakes, and pigments of every hue of the 
rainbow, are now common articles of trade. Their application has 
revolutionized the arts of the dyer and color-printer. 



QUESTIONS AND EXERCISES. 

878. Explain the production of color by the various natural and 
artificial pigments. 



542 GENERAL QUALITATIVE ANALYSIS. 

879. Mention the chief yellow coloring matters, and describe their 
chemical nature. 

880. What is annatto? 

881. Name the colorific constituent of madder. Can it be made 
artificially ? 

882. State the source of litmus. 

883. Distinguish between Prussian blue and Turnbull's blue, and 
state how they are manufactured. 

884. How is blue ultramarine obtained ? How is it affected by 
acids ? 

885. Describe the chemical nature of the coloring principle of 
green leaves. 

886. By what agents is glass colored green? 

887. Whence is sepia obtained? 

888. Describe the chemistry of black ink. 

889. Write a few sentences on aniline colors. 



QUALITATIVE ANALYSIS OF SUBSTANCES 
HAVING UNKNOWN PROPERTIES. 

Substances are presented to the analyst in one of the three forms 
in which all matter exists — namely, solid, liquid, or gaseous — and 
they may contain animal or vegetable as well as mineral matter. 

The method of analysis in the case of solid mineral bodies has 
been described on pp. 370 to 377. 

Solid animal or vegetable substances (or mixtures of these with 
mineral bodies) may be indefinite and beyond the grasp of chemis- 
try, or definite and quite within the range of proximate qualitative 
organic analysis. The presence of such substances is indicated in 
the preliminary examination of a solid (pp. 370 to 377.) by charring 
and other characters. If no charring occurs and no volatile liquid 
is expelled by heat, the absence of such matter is indicated. But 
if organic matter is present, an endeavor is made to ascertain its 
precise character. The analyst's knowledge of the history of the 
substance or the circumstances under which it comes into his hands 
will probably afford a clue to its nature, and enable him to search 
directly for its proximate constituents. If no such information is at 
hand, the action of solvents may be employed as likely to afford 
indication of the general, if not of the precise, nature of the substance. 
Water, alcohol, ether, chloroform, bisulphide of carbon, each both hot 
and cold, may in turn be agitated with the substance, the mixture 
filtered, a portion of the filtrate evaporated, at first partially, setting 
the product aside, and afterward to dryness, and any deposit or resi- 
due examined with and without the aid of a microscope. Other 
portions of the filtrate may be treated with acids, alkalies, and solu- 
tions of such metallic salts as are commonly used as group-tests for 
acidulous radicals (p. 367). The action of alkalies, as well as acids, 
weak and strong, hot and cold, may also be tried on the solid sub- 
stance itself, and colors, odors — and, in short, any effect whatever — 



GENERAL QUALITATIVE ANALYSIS. 543 

duly noted. A portion of the substance should also be burnt in an 
open porcelain crucible until no carbon remains, and the ash, if any, 
examined ; its amount and nature may afford information leading to 
the identification of the substance. 

The foregoing experiments having been carefully performed, and 
all results entered in the note-book, a little reflection will possibly 
lead to the recognition, or may suggest further direct experiments or 
confirmatory tests, or will, at least, have pointed to the absence of 
90 or 95 per cent, of all possible substances, and thus have restricted 
the area of inquiry to narrow limits. The success attainable in 
qualitative proximate organic analysis by the medical or pharma- 
ceutical student will of course largely depend on the thoroughness 
with which the operator has prosecuted his study of practical chem- 
istry generally ; but it also will be considerably affected by the 
extent to which he has cultivated the art of observation, and the op- 
portunities he has had of acquiring a knowledge of the appearance, 
uses, and common properties of definite chemical substances and of 
articles of food, drink, and medicine. The most successful of several 
good analysts will be the one who has most common sense and most 
experience. 

The pharmaceutical student, who has probably already had some 
years of experience in pharmacy, occupies an unusually favorable 
position for prosecuting the proximate analysis of organic and inor- 
ganic substances, or, at all events, of that large proportion of such 
bodies met with in the domain of hygiene and pharmacy. Many 
substances he will identify at sight, or by aid of a lens, or after 
applying some simple physical or chemical test. Nor should he 
find much difficulty, after reaching the present point Of practical 
study, in deciding whether the solid substance under examination 
belongs to the class of organic acids, organic salts of metallic radicals, 
alkaloids, salts of alkaloids, amylaceous matter, gums, saccharine sub- 
stances, glucosides, albumenoid matters, fats, soaps, resins, coloring 
matters, etc. For instance, the pharmaceutical student will find 
less difficulty than the general student in successfully analyzing a 
substance occurring in " scales," because he has experience of the 
appearances of compounds commonly produced in that form, and 
because, even if the appearance is new to him, he knows what kind 
of substances most readily lend themselves to production in that 
form. While the general student is testing generally and proceed- 
ing cautiously or searching for general information in books of ref- 
erence, the pharmaceutical or medical student has incinerated some 
of the material, noticed whether or not the ash is red (iron) and 
strongly alkaline (potassium), treated more of the material with an 
alkali (for ammonium), added excess of ammonia, and examined the 
precipitate (for cinchonine or quinine), or shaken up the alkaline 
liquid successively with ether and chloroform, and tested the residue 
of these decanted and evaporated solvents (quinine, beberine, strych- 
nine), and examined the aqueous solution of the material or one of 
the filtered alkaline liquids in the usual way for acidulous radicals 
(citric, tartaric, sulphuric, hypophosphorous). Or he has modified 
his methods to include search for some " scale preparation" which 



544 GENERAL QUALITATIVE ANALYSIS. 

his special knowledge tells him has been newly introduced to, or is 
rare in, pharmacy. 

In the ease of liquids the solvents as well as the dissolved matters 
claim attention. A few drops are evaporated to dryness on plati- 
num-foil to ascertain if solid matter of any kind is present ; the 
liquid is tested by red and blue litmus-paper to ascertain if free 
alkalies, free acids, or neither are present ; a few drops are heated 
in the test-tube and the odor of any vapor noticed, a piece of glass 
tubing bent to a right angle being, if necessary, adapted to the test- 
tube by a cork, and some of the distilled liquid collected and exam- 
ined ; finally, the usual group-reagents for the several basylous and 
acidulous radicals are consecutively applied. 

Proceeding in this way, the student who has already had some 
experience in pharmacy will not be likely to overlook such solvents 
as water, acids, alkalies, alcohol, glycerin, ether, chloroform, ben- 
zene, fixed oils, and essential oils, or to miss the substances which 
these menstrua may hold in solution. He will probably also recog- 
nize such liquids as carbolic acid, formic acid, lactic acid, methylic 
alcohol, aldehyde, aniline, nitrobenzol. He must not, however, sup- 
pose that he will always be able to qualitatively analyze, say, a bot- 
tle of medicine : for the various infusions, decoctions, tinctures, 
wines, syrups, liniments, confections, extracts, pill-masses, and pow- 
ders contain vegetable matters most of which at present are quite 
beyond the reach of the analyst. Neither the highest skill in anal- 
ysis nor the largest amount of experience concerning the odor, 
appearance, taste, and uses of drugs is sufficient for the detection of 
all these vegetable matters. Skill and experience combined, how- 
ever, will do much, and in most cases even so difficult a task as the 
one just mentioned be accomplished with reasonable success. Obvi- 
ously, qualitative analysis alone will not enable the experimenter 
to produce a mixture of substances similar to that analyzed ; to this 
end recourse must be had to quantitative analysis, a subject reserved 
for subsequent consideration. 

Natural fluids, as "Milk'' and "Urine" (vide Index), admit of 
special analytical treatment. 

Gas-analysis, or Eudiometry (from evSia, eudia, calm air, and 
/uerpov, metron, a measure, in allusion to the eudiometer, an instru- 
ment used in measuring the proportion and, as the early chemists 
thought, the salubrity of the gases of the air), is a branch of experi- 
mental investigation, chiefly of a quantitative character, concerning 
which information must be sought in other treatises. The analysis 
of atmospheric air from various localities, coal-gas, and gases 
obtained in chemical researches, involves operations which are 
scarcely within the sphere of Chemistry applied to Medicine. Be- 
yond the recognition, therefore, of oxygen, hydrogen, nitrogen, car- 
bonic, sulphurous, and hydrosulphuric acid gases, the experimental 
considerations of the chemistry of gaseous bodies may be omitted. 
Their stud}' , however, should not be neglected, as existing concep- 
tions of the constitution of chemical substances are largely depend- 
ent on the observed relations of the volumes of gaseous compounds 
to their elements. (See previous paragraphs, pp. 16 to 29, 42 to 45, 



CHEMICAL TOXICOLOGY. 545 

52 to 54, and 128.) The best single work on this latter part of the 
subject is a small book by Hofmann, Introduction to Modern Chem- 
istry. 

Spectrum Analysis. — It may be as well to state here that the pre- 
liminary and final examinations of minute quantities of solid matter 
may, in certain cases, profitably include their exposure to a tempera- 
ture at which they emit light, the flame being physically analyzed by 
a spectroscope. A spectroscope consists essentially of a prism to 
decompose a ray of light into its constituent colors, with tubes and 
lenses to collect and transmit the ray or rays to the eye of an 
observer. The material to be examined is placed on the end of a 
platinum wire, which is then brought within the edge of a spirit- 
lamp or other smokeless flame ; volatilization, attended usually in 
the case of a compound by decomposition, at once occurs, and the 
whole flame is tinged with a characteristic hue. A flat ribbon of 
rays is next cut off by bringing near to the flame a brass tube, the 
cap of which is pierced by a narrow slit. At the other end of the 
tube, at focal distance for parallel rays, is a lens through which the 
ribbon of light passes to a prism ; the prism decomposes the ribbon, 
spreading out its constituent colors like a partially-opened fan, and 
the colored beam or spectrum thus produced is then examined by 
help of a telescope attached by a movable joint to a stand which 
carries the prism and the object-tube. It is this combination of 
tubes, lenses, and prism or prisms which constitutes the spectroscope. 
Sodium compounds under the circumstances give yellow light only, 
indicated by a double band of light in a position corresponding to a 
portion of the yellow part of an ordinary solar spectrum. The 
potassium spectrum is mainly composed of a red and violet band ; 
lithium, a crimson, and, at very high temperatures, a blue, band. 
Most of the other elements give equally characteristic spectra. 

By aid of a combined microscope and spectroscope (micro-spectro- 
scope) the color of colored fluids can be analyzed. 



CHEMICAL TOXICOLOGY. 

In cases of criminal and accidental poisoning the substances pre- 
sented to the chemical analyst for examination are usually articles 
of food, medicines, or vomited matters, or the liver, kidneys, intes- 
tines, stomach and contents, removed in course of post-mortem exam- 
ination. In these cases some special operations are necessary before 
the poison can be isolated in a state of sufficient purity for the appli- 
cation of the usual tests ; for in most instances the large quantity 
of animal and vegetable — or, in one word, organic — matter present 
prevents or masks the characteristic reactions on which the tests are 
founded. These operations will now be described ;* they form the 

* Materials for these experiments are readily obtained for educational 
purposes by dissolving the poison in infusions of tea or coffee, in porter 
or in water, to which some mucilage of starch or linseed meal, pieces of 
bread, potato, and fat have been added. 



546 PRELIMINARY EXAMINATION. 

chemical part of the subject of Toxicology (rogucav, toxicon, poison, 
and ?„6-yoc, logos, discourse). 

Substances occurring in the form of an apparently definite salt or 
unmixed with organic matter need no special treatment. They are 
analyzed by the ordinary methods already given, attention being 
restricted to poisonous compounds only. 

Examination of an Organic Mixture Suspected to 
contain — Mercury, Arsenium, Antimony, Lead, Cop- 
per, or Zinc; Sulphuric Acid, Nitric Acid, Hydro- 
chloric Acid, Oxalic Acid, or Hydrocyanic Acid; 
Caustic Alkalies; Phosphorus; Strychnine, Mor- 
phine, or other Poisonous Alkaloids. 

Preliminary Exam mat ion. 

Odor, Appearance, Taste. — Smell the mixture, with the view 
of ascertaining the presence or absence of any notable quantity 
of free hydrocyanic acid. Look carefully for any small solid 
particles, such as arsenic, corrosive sublimate, or verdigris, and 
for any appearance which may be regarded as abnormal, any 
character unusual to the coffee, tea, beer, medicine, vomit, coats 
of stomach, kidney, liver, or other organ, tissue, or solid mat- 
ter under examination. 

Poisonous Quantity of Acid. — Add to a small portion some 
solution of carbonate of sodium, with the view of ascertaining 
by strong effervescence the presence of any large, poisonous 
quantity of sulphuric, nitric, or hydrochloric acid (p. 549). 

Poisonous Quantify of Alkali. — If so excessively alkaline as 
to require the addition of a very large quantity of acid before 
neutralization is effected, a noxious quantity of a corrosive or 
caustic alkali is present. Whether soda or potash, etc., is 
ascertained by the usual tests. 

Special instructions may induce the operator to suspect the 
presence of one particular poison. Direct examination for the 
latter may then be made, either at once if the substance has an 
aqueous character, or when filtration or treatment with warm 
hydrochloric or acetic acid has afforded a more or less colorless 
liquid. 

Fluids. — A vomit or the contents of a stomach, if set aside 
in a long narrow vessel (test-glass or ale-glass), or, better, 
exposed on a filter during a night, will often yield a more or 
less clear, limpid portion at the bottom or top of the solid mat- 
ter. This fluid (separated by a pipette or otherwise) will some- 
times respond to tests without further preparation, and always 
requires less preparatory treatment than a semi-solid mixture. 



MERCURY — A RSENIUM— ANTIMONY, ETC. 547 

If none passes through a filter, a portion often collects in the 
upper part. 

General Procedure. — If the preliminary examination does not 
indicate the method to be pursued, proceed as follows, treating 
a portion (not more than one-fourth) of the mixture for the 
poisonous metals, another for the acids, and a third for alka- 
loids, reserving the remainder for any special experiments which 
may suggest themselves in the course of analysis. 



Examination for Mercury, Arsenium, Antimony, Lead, 
Copper^ Zinc. 

If a liquid, acidulate with hydrochloric acid and boil for a 
short time. If solid or semi-solid, cut up the matter into small 
pieces, add enough water to form a fluid mixture, stir in 10 or 
20 per cent, of ordinary liquid hydrochloric acid, and boil 
until, from partial aggregation and solution of the solid mat- 
ter, filtration can easily be effected. 

Heat a portion of the clear liquid with a thin piece of bright 
pure copper or copper gauze, about an inch long and a quarter 
oj' an inch broad, for about ten or twenty minutes ; metallic 
mercury, arsenium, or antimony will be deposited on the cop- 
per, darkening it considerably in color. Pour off the liquid 
from the copper, carefully rinse the latter with a little cold 
water, dry the piece of metal by holding it over or near a flame 
(using fingers, not tongs, or it may become sufficiently hot for 
loss of mercury or arsenium to occur by volatilization), intro- 
duce it into a narrow test-tube or piece of glass tubing closed 
at one end, and heat the bottom of the tube in a flame, holding 
it horizontally, that the upper part of the tube may be kept 
cool, and partially closing the mouth with the finger to prevent 
escape of vapor. Under these circumstances any mercury will 
volatilize from the copper and condense on the cool part of the 
tube in a ring or patch of white sublimate, readily aggregating 
into visible globules on being pressed by the side of a thin 
glass rod inserted into the tube; arsenium will volatilize from 
the copper, and, absorbing oxygen from the air in the tube, 
condense on the cool part of the glass in a ring or patch of 
white sublimate of arsenic (gray or even darker if much 
arsenium as well as arsenic be present), not running into 
globules when rubbed, but occurring in small crystals, the 
characteristic octahedral form of which (vide p. 169) is readily 
seen by aid of a good hand lens or the low power of a micro- 
scope ; antimony volatilizes from the copper if strongly heated, 



548 CHEMICAL TOXICOLOGY. 

and, absorbing oxygen, immediately condenses as a slight white 
deposit close to the metal. 

Confirmatory Tests. — 1. Nothing short of the production of glob- 
ules should be accepted as evidence of the presence of mercury. It 
will usually have existed as corrosive sublimate. — 2. To confirm 
indications of the presence of arsenium, a portion of the acid liquid 
may be subjected to the hydrogen tests (pp. 170-172), or the tube 
containing the white crystalline arsenic may be broken, and the part 
on which the sublimate occurs boiled for some time in water, and 
the h}*drosulphuric-acid, amnion io-nitrate-of-silver, and amnionio-sul- 
phate-of-copper tests (pp. 173-175) applied to the aqueous solution. — 
3. For antimony, a portion of the acid liquid must always be intro- 
duced into the hydrogen-apparatus with the usual precautions. ( Vide 
p. 170.) — 4. Any sulphur present may darken the copper, and such 
stained copper may subsequently yield a whitish sublimate of sul- 
phur on the sides of the subliming tube ; such appearances, there- 
fore, are consistent with the entire absence of mercury, arsenium, 
and antimony. 

Note. — Before finally concluding that arsenium is absent from a 
fluid the latter should be warmed with a little sulphurous acid, and 
ordinary tests then again applied, for arsenic acid and other arse- 
niates are not readily affected by the usual reagents for arsenium. 

For Lead and Copper, pass hydrosulphuric acid gas through 
the clear acid liquid for some time, warming the liquid if no 
precipitate is produced, or diluting and partially neutralizing 
the acid by ammonia if much acid has been added. Collect 
on a filter any black precipitate that may have formed ; wash, 
dissolve in a few drops of aqua regia, dilute, and apply tests, 
such as ammonia for copper, sulphuric acid for lead, or any 
other of the ordinary reagents (pp. 190, 211). 

Copper may often he at once detected in a small quantity of acid- 
ulated liquid by immersing the point of a penknife or a piece of 
bright iron wire — a deposit of copper in its- characteristic color 
quickly or slowly appearing according to the amount present (p. 
189). 

Zinc. — To the acid liquid through which sulphuretted hydro- 
gen has been passed, add excess of ammonia (or to the original 
acid fluid add excess of ammonia, and then sulphydrate of am- 
monium) ; a precipitate falls which may contain alumina, phos- 
phates, and zinc — it is usually blackish, from the presence of 
sulphide of iron. Collect the precipitate on a filter, wash, dis- 
solve in a little hydrochloric acid, add a few drops of nitric 
acid, boil, pour in excess of ammonia, filter, and test the filtrate 
with sulphydrate of ammonium ; a white precipitate indicates 
zinc. 



MINERAL ACIDS, ETC. 549 

Examination for Mineral Acids, Oxalic Acid, or Hydrocyanic 
Acid. 

To detect Hydrochloric, Nitric, or Sulphuric Acid in any 
liquid containing organic matter, dilute with water and 
apply to small portions the usual tests for each acid, dis- 
regarding indications of small quantities. ( Vide pp. 265, 
287, 309.) 

Excessive sourness, copious evolution of carbonic acid gas on the 
addition of carbonate of sodium, and abundant evidence of acid on 
applying the various tests to small portions of the fluid presented 
for analysis, collectively form sufficient evidence of the occurrence 
of a poisonous amount of either of the three common mineral acids. 
Small quantities of the hydrochloric, nitric, and sulphuric radicals, 
occurring as metallic salts or acids, are common normal constituents 
of food ; hence the direction to disregard insignificant indications. 
If the fluid under examination be a vomit or the contents of a stom- 
ach, and an antidote has been administered, free acid will not be 
found, but, instead, a large amount of the corresponding salt. 

For Oxalic Acid, filter or strain a portion of the liquid, if 
not already clear, and add solution of acetate of lead so long 
as a precipitate occurs ; collect the precipitate — which in any 
case is only partly oxalate of lead — on a filter, wash, transfer 
it to a test-tube or test-glass, add a little water, and pass hydro- 
sulphuric gas through the mixture fo^ a short time ; the lead is 
thus converted into the insoluble form of sulphite, while any 
oxalic acid is set free in the solution Filter, boil to get rid of 
hydrosulphuric gas, and apply the usual tests for oxalic acid 
(see p. 315) to the clear filtrate. 

The contents of a stomach containing oxalic acid is often of a 
dark-brown color with a tinge of green (altered blood and mucus), 
and the viscid mixture generally, though slowly, affords some clear 
limpid, almost colorless, liquid by filtration on standing. 

For Hydrocyanic Acid, the three chief tests may be applied 
at once to the liquid or semi-liquid organic mixture, whether it 
has an odor of hydrocyanic acid or not. First : Half fill a small 
porcelain crucible with the material, add eight or ten drops of 
strong sulphuric acid, stir gently with a glass rod, and invert 
over the mouth of the crucible a watch-glass moistened with a 
small drop of solution of nitrate of silver; a white film on the 
silver solution is probably cyanide of silver, formed by the 
action of the gaseous hydrocyanic acid on the nitrate of silver. 
Second: Prepare a small quantity of the organic mixture as 
before, slightly moistening the centre of the watch-glass with 
solution of potash ; here, again, the heat generated by the 



550 CHEMICAL TOXICOLOGY. 

action of the strong acid is sufficient to volatilize some of the 
hydrocyanic acid, which, reacting on the potash, forms cyanide 
of potassium. On removing the watch-glass and stirring into 
it successively solution of a ferrous salt, a ferric salt, and 
hydrochloric acid, flocks of Prussian blue are produced if 
hydrocyanic acid is present. Third : Proceed as before, moist- 
ening the watch-glass with sulphydrate of ammonium ; after 
exposure to the hydrocyanic gas for five or ten minutes, add a 
drop of solution of ammonia, evaporate to dryness at a low 
temperature, and add a drop of hydrochloric acid and of solu- 
tion of perchloride of iron ; a blood-red color, due to sulpho- 
cyanate of iron, is produced if cyanogen is present. 

If the above reactions are not well marked, the organic mixture 
may be carefully and slowly distilled in a small retort, the neck of 
which passes into a bottle and dips beneath the surface of a little 
water at the bottom of the bottle, and the reagents then applied to 
separate portions of the distillate. 

The examination of organic mixtures for hydrocyanic acid must 
be made without delay, as the poison soon begins to decompose, and 
in a day or two is usually destroyed. 

Examination for Phosphorus. 

A paste containing phosphorus is commonly employed for 
destroying vermin. In cases of poisoning the phosphorus is 
generally in sufficient quantity to be recognized by its charac- 
teristic unpleasant smell. A stomach in which it occurs not 
unfrequently exhibits slight luminosity if opened in a dark 
room. When the phosphorus is too small in quantity or too 
much diffused to afford this appearance, a portion of the mate- 
rial is placed in a flask, water acidulated by sulphuric acid 
added, a long wide glass tube fitted to the neck of the flask by 
a cork, and the mixture gently boiled. If phosphorus is pres- 
ent (even 1 part in 2,000,000, according to De Vrij), the top 
of the column of steam as it condenses in the tube will appear 
distinctly phosphorescent when viewed in a dark room. From 
its liability to oxidation, phosphorus cannot be detected after 
much exposure of an organic mixture to air. 

Examination for Strychnine and Morphine. 

Strychnine. — If solid or semi-solid, digest the matter with 
water and about 10 per cent, of hydrochloric acid till fluid ; 
filter, evaporate to dryness over a water-bath. If the organic 
mixture is already liquid, it is simply acidulated with hydro- 
chloric acid and evaporated to dryness. The acid residue is 



STRYCHNINE. 551 

next treated with spirit of wine as long as anything is dis- 
solved, the filtered tincture evaporated to dryness over the 
water-bath, and the residue digested in water and filtered. 
This slightly acid aqueous solution must now be rendered 
alkaline by ammonia, and well shaken in a closed bottle or 
long tube with about half an ounce of chloroform, and set 
by till the chloroform has subsided. The chloroform (which 
contains the strychnine) is then removed by a pipette, the 
presence of any aqueous liquid being carefully avoided, and 
evaporated to dryness in a small basin over a water-bath, the 
residue moistened with concentrated sulphuric acid, and the 
basin kept over the water-bath for several hours. (It is highly 
important that the sulphuric acid used in this operation should 
be free from nitrous compounds. Test the acid, therefore, by 
adding powdered sulphate of iron, which becomes pink if ni- 
trous bodies are present. If these are found, the acid should 
be purified by strongly heating with sulphate of ammonium, 
seventy or eighty grains to a pint.) The charred material is 
exhausted with water, filtered, excess of ammonia added, the 
filtrate shaken with about a quarter of an ounce of chloroform, 
the mixture set aside for the chloroform to separate, and the 
chloroform again removed. If on evaporating a small portion 
of this chloroform solution to dryness, adding a drop of sul- 
phuric acid to the residue, and warming, any darkening in color 
or charring takes place, the strychnine is not sufficiently pure 
for chemical detection ; in that case the rest of the chloroform 
must be removed by evaporation, and the residue redigested in 
warm sulphuric acid for two or three hours. Dilution, neutral- 
ization of acid by ammonia, and agitation with chloroform are 
again practised, and the residue of a small portion of the chlo- 
roform solution once more tested with sulphuric acid. If char- 
ring still occurs, the treatment must be repeated a third time. 
Finally, a part of the chloroform solution is taken up by a 
pipette and drop after drop evaporated on one spot of a por- 
celain crucible-lid until a fairly distinct dry residue is obtained. 
A drop of sulphuric acid is placed on the spot, another drop 
placed near, a minute fragment of red chromate of potassium 
placed in the second drop, and, when the acid has become tinged 
with the chromate, one drop drawn across the other ; the cha- 
racteristic evanescent purple color is then seen if strychnine is 
present. Other tests (vide p. 391) may be applied to similar 
spots. 

This is Girdwood and Rogers's method for the detection of strych- 
nine when mixed with organic matter. It is tedious but trustworthy. 



552 CHEMICAL TOXICOLOGY. 

and, though apparently complicated, very simple in principle, thus : 
strychnine is soluble in acidulated water or alcohol or in chloro- 
form, readily removed from an alkaline liquid by agitation with 
chloroform, and not charred or otherwise attacked when heated to 
212° F. with sulphuric acid ; much of the organic matter of the food 
is insoluble in water ; of that soluble in water, much is insoluble in 
alcohol ; and of that soluble in both menstrua, all is charred and 
destroyed by warm sulphuric acid in a shorter or longer time. (See 
also Stas's general process, p. 553.) 

Morphine and the Meconic Acid ivith which it is Associated in 
Opium. — To the liquid or the semi-fluid mixture warmed for 
some time with a small quantity of acetic acid, filtered, and 
concentrated if necessary, add solution of acetate of lead until 
no further precipitate is produced. Filter and examine the 
precipitate for meconic acid, reserving the filtrate for the 
detection of morphine. 

The Precipitate. — Wash the precipitate (meconate of lead, 
etc.) with water, place it in a test-tube or test-glass with a 
small quantity of water, pass hydrosulphuric acid gas through 
the mixture for a short time, filter, slightly warm in a small 
basin, well stirring to promote removal of excess of the gas, 
and add a drop of neutral solution of perchloride of iron ; a 
red color, due to the formation of meconate of iron, is pro- 
duced if meconic acid is present. This color is not destroyed 
on boiling the liquid after the addition of one drop of diluted 
hydrochloric acid, as is the case with ferric acetate, nor is it 
bleached by solution of corrosive sublimate, thus distinguish- 
ing it from ferric sulphocyanate. It is discharged by hydro- 
chloric acid. 

The Filtrate. — The solution from which meconic acid has 
been removed by acetate of lead is evaporated to a small bulk 
over a water-bath, excess of carbonate of potassium added, and 
evaporation continued to dryness. The residue is then treated 
with alcohol, which dissolves the morphine. The alcoholic 
solution evaporated similarly may leave the morphine suf- 
ficiently pure for the application of the usual tests (vide p. 
384) to small portions of the residue. If no reaction is 
obtained, add a drop of sulphuric acid and a little water to 
the residue, and shake with ether, in which the salt of mor- 
phine is insoluble. The treatment with ether may be repeated 
until nothing more is removed, the acid aqueous liquid satu- 
rated with carbonate of potassium, the mixture evaporated to 
dryness, the residue digested in alcohol, filtered, and portions 
of the alcoholic liquid evaporated to obtain spots of morphine 
for the application of the ordinary tests. 



MORPHINE — OTHER POISONOUS ALKALOIDS. 553 

If much organic matter is believed to remain in the nitrate 
after the acetate-of-lead treatment, or if a considerable excess 
of acetate of lead has been employed, the filtered liquid should 
be subjected to a current of sulphuretted hydrogen until no 
more sulphide of lead is precipitated, the mixture filtered, and 
the filtrate, with the washings from the sulphide of lead, evap- 
orated to a small bulk, excess of carbonate of potassium added, 
and the whole well mixed and agitated with twice or thrice its 
bulk of a mixture of ether and acetic ether (ether alone might 
not dissolve the morphine). On standing, the ethereal liquid 
rises to the surface ; it is carefully removed, evaporated to dry- 
ness, and the residue tested or further purified in the manner 
described in the preceding paragraph. 

The examination for morphine must be conducted with great care, 
and with as large a quantity of material as can be spared ; for its 
isolation from other organic matter is an operation of considerable 
difficulty, especially when only a minute proportion of alkaloid is 
present. Fortunately, the detection of meconic acid does not include 
similar difficulties 5 and, as its reactions are quite characteristic, its 
presence is held to be strong evidence of the existence of opium in 
an organic mixture. 

Examination for Other Poisonous Alkaloids. 

Sfass Process. — Minutely subdivide any solid matter ; to this 
and the^ liquid portion of the vomit, etc. add about twice their 
weight of the strongest spirit of wine containing sufficient tar- 
taric acid to fairly acidify the mixture. Digest the whole in a 
flask at a temperature of 150° or 160° F. ; set aside to cool ; 
filter. The solution, which will contain the whole of the alka- 
loid, should then be evaporated nearly to dryness in vacuo, or 
at all events at a temperature not exceeding 100° F., lest vola- 
tile alkaloids should be dissipated. The residue is next ex- 
hausted with cold anhydrous alcohol, filtered, and the filtrate 
evaporated to dryness with the precautions already stated. 
The extract is dissolved in a very small quantity of water, 
treated with excess of powdered bicarbonate of sodium or 
potassium, and well shaken with five or six times its volume 
of pure ether (with perhaps a little acetic ether). This ethe- 
real liquid contains the alkaloid. Small portions should be 
evaporated in watch-glasses and tasted, or tested physically 
and chemically, according as the knowledge of collateral cir- 
cumstances by the operator, or his experience, or such reac- 
tions as are recorded on pp. 392-399, may suggest. 

If a volatile alkaloid (conine, nicotine, lobelme) is indicated, 
47 



554 CHEMICAL TOXICOLOGY. 

the ethereal solution, which may still contain animal matter, is 
removed, agitated with aqueous solution of potash, decanted, 
and shaken with pure diluted sulphuric acid. On standing, 
the aqueous portion, containing the alkaloid as acid sulphate, 
subsides ; the upper ethereal portion containing the animal 
matter is rejected ; the acid aqueous liquid is made alkaline 
with caustic potash or soda ; ether added ; well shaken ; the 
ethereal liquid decanted, evaporated to dryness in vacuo or at 
a low temperature, and (to get rid of all traces of ammonia) 
again moistened with ether and dried. The residue is now 
tested for the suspected alkaloid by taste, smell, and the appli- 
cation of appropriate reagents (pp. 392-399). 

If a non-volatile alkaloid (aconitine, atropine, brucine, col- 
chicine, emetine, physostigmine, solanine, veratrine, as well as 
morphine, codeine, and strychnine) is indicated, further puri- 
fication is effected by decanting the ethereal liquid from the 
lower aqueous solution of bicarbonate of sodium, removing the 
ether by evaporation, digesting the residue in alcohol, filtering, 
evaporating the alcohol, treating the residue with diluted sul- 
phuric acid, setting aside for a few hours, filtering, concen- 
trating, adding powdered carbonate of potassium, and finally 
anhydrous alcohol. The alcoholic liquid, on evaporation, 
yields the alkaloid in a fit state for testing in the manner 
already stated. 

SonnenscheirC s Process. — Digest with diluted hydrochloric 
acid, evaporate to the consistence of syrup, dilute, set aside 
for some hours, filter. Add solution of phosphomolybdic acid 
so long as any precipitate falls or cloudiness occurs ; collect the 
precipitate on a small filter ; wash it with water containing 
phosphomolybdic and nitric acids, and, while still moist, place it 
in a flask. Decompose this compound of phosphomolybdic 
acid and alkaloid by adding caustic baryta until the stirred 
mixture is distinctly alkaline. Distil off volatile alkaloids, 
condensing and collecting by help of a long tube so bent that 
the apparatus shall act as a retort, the end of the tube being 
attached to a bulb or a series of bulbs containing diluted hydro- 
chloric acid. The acid liquid evaporated gives a residue of 
hydrochlorates of alkaloids. The latter will afford characteris- 
tic reactions with the tests for the suspected alkaloid, and on 
being moistened with baryta-water and warmed will afford fumes 
of volatile alkaloids whose odor is usualty characteristic. The 
residue in the flask will contain non-volatile alkaloids. It is 
treated with carbonic acid gas to neutralize and precipitate the 
excess of baryta as insoluble carbonate of barium ; the mix- 



REAGENTS FOR ALKALOIDS. 555 

ture is evaporated to dryness over a water-bath, and the residue 
digested in alcohol. The alcoholic solution evaporated gener- 
ally yields the alkaloids in a fit state for testing. 

Reagents for Alkaloids. 

Phosphomolybdic acid forms with ammonia, in acid solutions, a 
remarkably insoluble compound, and it comports itself in a similar 
manner with those compounds which are analogous to ammonia — 
the nitrogenized organic bases — consequently forming an excellent 
reagent for their detection. It may be prepared in the following 
manner : Molybdate of ammonium is precipitated by phosphate of 
sodium ; the yellow precipitate, having been washed, is diiFused 
through water and heated with sufficient carbonate of sodium to dis- 
solve it. The solution is then evaporated to dryness, and calcined to 
drive off the ammonia. In case any of the molybdic compound be 
reduced by this operation, the residue must be moistened with nitric 
acid and again calcined. The dry mass is then dissolved in cold 
water, the solution strongly acidulated with nitric acid, and water 
added until ten parts of the solution contain one of the dry salt. 
The liquid, which is of a golden-yellow color, must be preserved 
from ammoniacal fumes. It precipitates all the alkaloids (with the 
exception of urea) Avhen a mere trace only is present. The precipi- 
tates are yellow, generally flocculent, insoluble in water, alcohol, 
ether, and the diluted mineral acids, with the exception of phos- 
phoric acid. — Nitric, acetic, and oxalic acids, concentrated and boil- 
ing, dissolve them. These compounds are decomposed by the alka- 
lies, certain metallic oxides, and the alkaline salts, which separate 
the alkaloid. To give an idea of the sensitiveness of this reagent, it 
may be stated that the 0.000071 gramme of strychnine gives an 
appreciable precipitate with one cubic centimetre of the solution of 
phosphomolybdic acid. 

Phosphoantimonie and phosphotungstic acids are also precipitants 
of alkaloids. The chlorides of platinum, iridium, palladium, and 
gold are occasionally serviceable. Tannic and picric acids may, too, 
be used, and a solution of iodine and iodide of potassium. 

Other special reagents for alkaloids are "Meyer's" and "Ness- 
lers" (see Index), the double iodide of potassium and cadmium, 
and a solution of the double "Iodide of Bismuth and Potassium."' 
The latter is made (by Thresh) on adding together one ounce of 
Liquor Bismuthi, B. P., 90 grains of iodide of potassium, and 90 
grains of strong hydrochloric acid. This orange-colored solution 
gives a red precipitate with dilute cold solutions containing alka- 
loids. 

Ptomaines (fl-roy/a, a corpse) have already been alluded to as 
including poisonous alkaloids producible from putrefying animal 
matters, even the human body itself, during the ordinary processes 
of decay. They are distinguished, according to Brouardel and 
Boutmy, by a drop or two of a solution of their sulphate converting 
a drop of solution of ferrocyanide of potassium into ferricyanide, 
the mixture then giving a dark-blue precipitate with a ferric salt. 



556 CHEMICAL TOXICOLOGY. 

Unfortunately, some other substances also possess this converting 
power. 

Tyrotoxicon. — This ptomaine (p. 519) may be isolated and tested 
as follows : Prepare an aqueous extract of the cheese or filter the 
coagulated milk, etc. No heat should be applied, and undue expo- 
sure to air should be avoided by using stoppered bottles. Make the 
filtered fluid faintly alkaline with carbonate of sodium, and well 
shake with half its bulk of ether. Allow the perfectly clear ethereal 
solution to evaporate spontaneously. If necessary, again extract 
the aqueous residue with water, shaking with ether and evaporating 
as before. The aqueous residue may be tested in two or three w r ays. 
A little placed on the tongue and swallowed will cause more or less 
of nausea, vomiting, purging, and headache. The aqueous residue 
is either characteristically crystalline or will become so after stand- 
ing in a vacuum over sulphuric acid. Mix two or three drops of 
sulphuric acid and carbolic acid on a white plate, and add a few 
drops of the aqueous residue just mentioned ; if an orange-red or 
purple color results, the presence of tyrotoxicon may be suspected, 
but any nitrate or nitrite present may cause a similar color. To 
some of the aqueous residue add an equal volume of a saturated solu- 
tion of caustic potash ; the double hydrate of potassium and diazo- 
benzene is then formed, and appears in six-sided plates, whereas any 
nitrate of potassium appears in prisms. This residue may be treated 
with absolute alcohol, filtered, and the filtrate evaporated, when the 
plates may again be observed, or the color reaction again obtained 
with this now purified product (Vaughn). 

Obscure Poisons. — Many substances, the active principles of which 
are at present beyond the reach of the chemical analyst, are poisons 
of a more or less active character. (See the Pharmaceutical Journal 
for Sept. 6, 1879, p. 195, and for Dec. 20, 1879, p. 481.) 



ANTIDOTES. 

Vide " Antidotes " in the Index. 



QUESTIONS AND EXERCISES. 

890. In examining food and similar matter for poison, why must 
not the ordinary tests for the poison be at once applied? 

891. What preliminary operations should be performed on a 
vomit in a case of suspected poisoning ? 

892. How would you proceed in searching for corrosive sublimate 
in wine ? 

893. By what series of operations would you satisfy yourself of 
the presence or absence of arsenic in the contents of the stomach ? 

894. Describe the treatment to which decoction of coffee should be 
subjected in testing it for tartar emetic. 

895. State the method by which the occurrence of lead in water is 
demonstrated. 



EXAMINATION OF MORBID URINE. 557 

896. Give a process for the detection of copper in jam. 

897. How would you detect zinc in a vomit? 

898. How may the presence of a poisonous quantity of sulphuric 
acid in gin be proved? 

899. In examining ale for free nitric acid, what reactions would 
be selected? 

900. Show how you would conclude that a dangerous quantity of 
hydrochloric acid had been added to cider. 

901. Describe the manipulations necessary in testing for hydro- 
cyanic acid in the contents of a stomach. 

902. By what method is oxalic acid discovered in infusion of coffee ? 

903. How is phosphorus detected in organic mixtures? 

904. Give the process by which strychnine is isolated from par- 
tially digested food. 

905. Mention the experiments by which the presence of laudanum 
in porter is demonstrated. 

906. Name the appropriate antidotes in cases of poisoning by — a, 
alkaloids ; h, antimonials ; c, arsenic ; d, barium salts ; e, copper 
compounds ; f, hydrochloric acid ; g, hydrocyanic acid ; h, prepara- 
tions of lead ; i, corrosive sublimate ; j, nitric acid ; &, oxalic acid ; 
Z, salts of silver ; m, oil of vitriol ; n, tin liquors ; o, zinc solutions ; 
p, carbolic acid. 



EXAMINATION OF MORBID URINE AND 
CALCULI. 

The various products of the natural and continuous decay of ani- 
mal tissue and the refuse matter of food are eliminated from the sys- 
tem chiefly as feces, urine, and expired air. Air exhaled from the 
lungs carries off from the blood much carbon (about 8 ounces in 
twenty-four hours) in the form of carbonic acid gas, and some aque- 
ous vapor — the latter, together with a small amount of oily matter, also 
escaping by the skin. Directing the breath to a cold surface renders 
moisture evident, and breathing through a tube into lime-water dem- 
onstrates the presence of a considerable quantity of carbonic acid gas. 
The feces consist mainly of the insoluble debris of the system, the 
soluble matters and water forming the urine. These excretions 
vary considerably, according to the food and general habits of the 
individual and external temperature. But in disease the variations 
become excessive ; their detection by the medical practitioner, or by 
the pharmacist for the medical practitioner, is therefore a matter of 
importance. 

A complete analysis of feces, urine, or expired air cannot be per- 
formed in the present state of our knowledge. Nor can even a par- 
tial analysis of feces or air be made with sufficient ease and rapidity 
to be practically available in medical diagnosis. But with regard to 
urine, certain abnormal substances and abnormal quantities of nor- 
mal constituents may be chemically detected in the course of a few 
minutes by any one having already some knowledge of chemical 
manipulation. 
47* 



558 MORBID URINE. 

Healthy human urine contains, in 1000 parts, 957 of water, 14 of 
urea, 1 of uric acid, 15 of other organic matter, and 13 of inorganic 
salts. The amount passed in twenty-four hours varies from two to 
three pints in an adult, and its specific gravity, if healthy, will range 
from 1.015 to 1.025. The acidity of urine Thudichum considers to 
be due to cryptophanic acid, H 2 C 5 H 7 N0 5 . 

Physical Examination of Urine. 

Normal urine is either of a pale yellow or faintly reddish yellow ; 
it has a reddish-brown tint if blood is present, or greenish-brown if 
bile is present ; both color and odor are much influenced by certain 
kinds of food and by some drugs. 

Fresh urine is clear ; any turbidity may be due to urates, phos- 
phates, or pus. Urates redissolve when the urine is warmed ; phos- 
phates by the addition of acetic acid ; pus is detected by the micro- 
scope (vide infra). If the urine be turbid from the presence of 
phosphates when first voided, it may be due to conversion of urea 
into carbonate of ammonium within the bladder, in which case the 
fresh and warmed urine will effervesce slightly on the addition of 
acetic acid. This condition is abnormal. 

On standing, healthy urine commonly gives a slight cloud of 
mucus, and after severe exercise or after a hearty nitrogenous meal 
may give a sediment of urates. 

The specific gravity of urine should be taken on a specimen re- 
moved from the whole bulk excreted in twenty or twenty-four 
hours. Many qualitative experiments and all quantitative opera- 
tions should only be performed on the mixed urine of twenty-four 
hours. If pale urine has high specific gravity or if dark-colored 
urine has low specific gravity, some abnormal condition of the sys- 
tem obtains. 

Healthy urine, when fresh, is always slightly acid, the acidity 
being said to be due to the presence of acid phosphate of sodium. 
Alkalinity is probably due to that conversion of urea into carbonate 
of ammonium within the bladder already described. 

Examination of Morbid Urine for Albumen, Sugar, 
Bile, and Excess of Urea ; and Urinary Sediment 
for Urates (or Lithates), Phosphates, Oxalate of 
Calcium, and Uric Acid. 

Albumen. — To detect albumen, acidulate a portion of the 
clear urine in a test-tube with a few drops of diluted nitric 
acid (to keep phosphates in solution), and boil ; flocks or 
coagula will separate if albumen be present. Or pour cold 
nitric acid down the sides of an inclined test-tube containing 
the urine ; a coagulum appears between the layers of fluid if 
albumen be present. 

These experiments should be first made on normal urine contain- 



PHYSICAL EXAMINATION. 559 

ing a drop or two of solution of white of egg. The coagulum is 
white if it is only albumen, greenish if bile-pigment be present, and 
brownish-red if the urine contain blood. The influence of acids 
and alkalies on the precipitation of albumen is noticed on anoth- 
er page. 

A saturated solution of picric acid at once precipitates any albu- 
men from urine. Should the urine be alkaline, it must be acidified 
before applying this test. On warming the mixture the precipitate 
will become more pronounced if due to the albumen or globulin of 
blood or to any modifications of albumen caused by acidity or alka- 
linity of urine ; but it will disappear if clue to peptone or propep- 
tone. Ferrocyanide of potassium also will precipitate the former 
varieties of albumen, but not the peptones. 

The occurrence of albumen in the urine may be temporary and 
of but little importance, or it may indicate the existence of a serious 
affection known as Bright' s disease. "Albuminuria is rarely a seri- 
ous condition unless it is sufficiently pronounced to be made out by 
the cold nitric-acid test" (Stewart). 

For quantitative purposes Esbach employs the picric test, dissolv- 
ing 10 parts of picric acid and 20 of citric acid in 900 of water by 
aid of heat, and, when the solution is cold, diluting with water to 
1000 parts. This solution is added to a given volume of urine in a 
graduated Cetti's-Esbaeh tube, and the height of the precipitate is 
noted after twenty-four hours. Johnson finds a simple solution of 
5 grains of picric acid in 1 fluidounce of water better than Esbach's 
solution, because the excess of acid in the latter tends to precip- 
itate much uric acid, which would be reckoned as albumen. A 
standard value is given to the solutions in the first instance by 
washing^ drying, and weighing the albumen. 

Sugar. — To a portion of the clear urine in a test-tube add 
five or ten drops of solution of sulphate of copper ; pour in 
solution of potash or soda until the precipitate first formed is 
redissolved ; slowly heat the solution to near the boiling-point ; 
a yellow, yellowish-red, or red precipitate (cuprous oxide) is 
formed if sugar be present. (The production of a rose-red 
or pink tint with the cold alkaline copper solution indicates 
the presence of the altered non-coagulable albumenoids termed 
pcj)to>ies.) 

This experiment should be first made on urine containing a drop 
or two of solution of grape-sugar (p. 458). The hydrate of copper 
precipitated by the alkali is insoluble in excess of pure potash or 
soda, but readily dissolves if organic matter, especially sugar, bo 
present. The copper salt should not contain iron. 

Other tests may be applied if necessary. (Vide p. 555. See also 
" Sugar, quantitative estimation of,'' in Index.) 

A minute amount of sugar is said to occur in normal urine, and a 
distinct trace is occasionally present. In larger quantities (often 5 
per cent.) it is a characteristic constituent of the urine of diabetic 



560 MORBID URINE. 

patients, greatly increasing the specific gravity of the excretion. 
Small hydrometers (termed urinometers) are commonly employed 
for quickly and readily ascertaining the specific gravity of urine ; 
they range from 1.000 to 1.050, the interval of 1.015 to 1.025 being 
marked as " h. s." or " healthy state.'' (Vide ; ' Specific Gravity'* 
and "Hydrometers"' in Index ; also '"Sugar, quantitative estima- 
tion of.") 

Bile. — This is best detected by the dark greenish-brown color of 
the urine and by the general test (Pettenkofer's, or still better, 
Quinlan's) described on page 635. Or a little of the urine may be 
placed on a white plate and strong nitric acid dropped on it : a 
peculiar play of colors — green, yellow, violet, etc. — occurs if (the 
coloring-matter of) bile be present (Gmelin). A somewhat similar 
iridescence is produced in the presence of the indigo-forming matter 
occasionally found in urine. Oliver recommends that the urine be 
diluted to a sp. gr. of 1.008, and then one volume be added to three 
volumes of the following reagent, when more or less of opalescence 
will be produced according to the amount of bile acids present. 
For the reagent, dissolve 30 grains of flesh peptone, 4 grains of sali- 
cylic acid, and 33 minims of official acetic acid in 8 ounces of water ; 
filter. 

Excess of Uric Acid. — A rough quantitative process consists 
in applying the qualitative method already described (p. 357) 
to a known volume of urine and collecting on a filter, and 
washing and weighing the resulting uric acid. The result is 
always a little low. A more accurate method, by Haycraft, 
consisting in the formation and volumetric estimation of urate 
of silver, will be found described in the Pharmaceutical Jour- 
nal, 3d Ser. vol. xvii. p. 858. 

Excess of Urea. — About one-third of the solid matter in the 
urine is urea. Its proportion varies considerably, but 1J per 
cent, may be regarded as an average amount. Concentrate 
urine slightly by evaporation in a small dish, pour the liquid 
into a test-tube, set the tube aside till cold or cool it by letting 
cold water run over the outside, add an equal bulk of strong 
nitric acid, and again set aside ; scaly crystals of nitrate of 
urea are deposited more or less quickly. 

With regard to the amount of urea in urine, it is impossible to 
sharply define excess or deficiency. If nitric acid gives crystals 
without concentration, excess is certainly present in the sample 
examined, though if the amount of urine passed in the twenty- 
four hours is much below the average the quantity excreted daily 
may not be abnormal. A rough estimate may be formed by mixing 
a few drops of the urine and acid on a piece of glass and setting 
aside ; the time which elapses before crystals form is an indication 
of the quantity in the specimen. The time Avill vary according to 
the temperature and state of moisture of the atmosphere, but with 
care some useful comparative results may in this way be obtained. 



UREA. 



561 



For trustworthy quantitative estimations the urine is shaken with 
an alkaline solution of hypobromite of sodium, and the nitrogen 
then liberated collected and measured. The reaction is of the 
following character : — 



H 4 N 2 + 3NaBrO — 


3NaBr + C0 2 + 2H 2 + N 2 


Urea. Hypobromite 


Bromide Carbonic Water. Nitrogen 


of sodium. 


of sodium. acid gas. 



Fig. 50. 



The whole of the nitrogen of the urea, however, is not evolved, 
while, on the other hand, some of the produced nitrogen is yielded 
by the uric acid, hippuric acid, and creatinine of the urine. Neither 
fact is of any consequence in this examination of urine, for a given 
specimen of urine always yields the same quantity of gas ; hence a 
given volume of gas always indicates the same percentage of urea, 
and once a measuring-tube is so divided as to indicate percentages 
of urea when a given volume of 
urine is used, it may be trusted to 
indicate the varying percentages of 
urea in the urine of one patient or 
the different proportions of urea in 
the urine of different patients. The 
method is Davy's, with improvements 
and modifications of apparatus by 
Knop, Hufner, Russell and West, 
Apjohn, Dupre, Gerrard, Gillet, and 
others. In the chemical laboratory 
appliances already at hand may be 
adapted for the operation. Thus, as 
shown in the accompanying wood- 
cut, any two-ounce or three-ounce 
bottle serves for the reaction be- 
tween the hypobromite and urine ; 
a 50 or 60 c.c. burette, containing 
water, may be the measuring-tubo ; 
while a funnel, supported in the 
ring of a retort-stand, serves both 

as a reservoir for water displaced by the evolved nitrogen and as 
a means of getting that equal level of water within and without the 
measuring-tube which shall prevent misleading attenuation or com- 
pression of the nitrogen. Attach the funnel to the bottom of the 
burette by india-rubber tubing. Attach a short glass tube by a 
pierced cork to the top of the burette, and by more india-rubber 
tubing connect this glass tube with a similar tube in the well-fitting 
india-rubber cork of the gas-generating bottle. Disconnect the lat- 
ter. Into the funnel pour water until it rises to the zero-mark of 
the burette and a little water remains in the bottom of the funnel. 
Into the generating-bottle pour about 25 c.c. of solution of soda 
(made by dissolving about 100 grammes of solid soda in 250 e.e. ol' 
water) and about 2.5 c.c. of bromine. Into the bottle containing 
the hypobromite solution thus prepared a short test-tube containing 
5 c.c. of urine is lowered, care being taken that no urine is spilt. 




562 MORBID URINE. 

The cork is reinserted and the water-level again adjusted (best 
accomplished if into the cork of the generating-bottle be fitted a 
short glass tube, the external orifice of which can be closed by a 
cork or a cap as soon as the apparatus is ready for use). The gen- 
erating-bottle is now inclined, when, the urine and hypobromite 
mixing, nitrogen is at once evolved (the carbonic acid produced at 
the same time being absorbed by the strongly alkaline fluid in the 
bottle). The funnel is lowered until the surfaces of the water inside 
and outside the measuring-tube are on a level ; after ten or fifteen 
minutes the level is finally adjusted and the amount of produced 
gas noted. Every 55 c.c. of gas indicates 0.15 of a gramme of urea, 
the temperature being about 66° F. and the height of the barometer 
being about 30 inches. In cases in which frothing interferes put a 
fragment of suet into the generating-bottle. 

Tests. — Urea in solution in water may be detected by the reaction 
with nitric acid and by the readiness with which it yields ammonia on 
being boiled with alkalies. In putrid urine its conversion into an am- 
moniacal salt has already been effected by ammoniacal fermentation. 

CH 4 N 2 + 2II 2 = (NH 4 ) 2 C0 3 . 

Urea. Water. Carbonate of ammonium. 

This transformation of the urea into carbonate of ammonium is 
due to the action of a special ferment belonging to the genus Toru- 
lacei, formed of chaplets of globules similar in form to, but much 
smaller than, those of beer yeast. It occurs as a white deposit in 
the urine. If some of this deposit be added to a saccharine solution 
containing urea, it rapidly multiplies, carbonate of ammonium being 
formed. 

Formula of Urea. — The empirical formula of urea is CH 4 N 2 0. 
Its rational formula may be thus written : — 

nh ( co n 
co< nh: » | }».! 

that is, it may be regarded as carbamide or as one of the organic 
bases already referred to, a primary diamine, in which the bivalent 
radical CO occupies the place of H 2 . The other atoms of hydrogen 
may be displaced by various radicals, and many compound ureas 
thus be obtained. 

Artificial Urea. — Urea may be prepared artificially by Williams's 
modification of Wbhler's method. Cyanide of potassium, of the best 
commercial quality (containing about 90 per cent, of real cyanide), 
is fused at a very low red heat in a shallow iron vessel ; red lead is 
added in small quantities at a time, the temperature being kept down 
by constant stirring. When the red lead ceases to cause further 
action, the mixture (cyanate of potassium and lead) is allowed to 
cool, the product finely powdered, exhausted with cold water, nitrate 
of barium added till no more precipitate (carbonate of barium) falls, 
the mixture filtered, and the filtrate treated with nitrate of lead so 
long as cyanate of lead is thrown down. The latter is thoroughly 
washed, and dried at a low temperature. Equivalent quantities of 



URINARY SEDIMENTS. 563 

cyanate of lead and sulphate of ammonium digested in a small 
quantity of water with a little heat (vide p. 338) and filtered, yield 
a solution from which urea crystallizes on cooling. 

Another Process. — Basaroff has found that urea is produced when 
ordinary carbonate of ammonium is heated in strong hermetically- 
sealed tubes to about 275° F. for a few hours. The same chemist 
had previously obtained urea by similarly heating pure carbamate 
of ammonium ; so that the source of the urea in the former case is 
probably the carbamate of ammonium believed to occur in the car- 
bonate (see p. 91). 

NII 4 NH 2 C0. 2 — II 2 = CH 4 N a O. 

Urinarv Sediments. 

Notes. — Urinary deposits are seldom of a complex character : the 
action of heat and acetic and hydrochloric acids generally at once 
indicates the character of the deposit, rendering filtration and pre- 
cipitation unnecessary. 

The Urates are often of a pink or red color, owing to the presence of 
a pigment termed purpurine ; hence the common name of red gravel 
for such deposits. Purpurine is soluble in alcohol, and may be 
removed by digesting a red deposit in that solvent. It is seldom 
necessary to determine whether the urate be that of ammonium, cal- 
cium, or sodium (see also "Uric Acid,*' page 361). The deposited 
urate is a very acid urate which slowly (more rapidly in urine 
diluted with water) breaks up into a less acid urate and uric acid 
(Bence-Jones). The occurrence of the salines of our food, especially 
dipotassic phosphate, is apparently (Roberts) what prevents this 
decomposition before the urine is exposed to the air. 

The phosphate of calcium and the ammonio-magnesium phosphate 
are usually both present in a phosphatic deposit, the magnesium 
salt forming the larger proportion. They may, if necessary, and if 
sufficient in quantity, be separated by collecting on a filter, washing, 
and boiling with solution of carbonate of sodium. The carbonates 
of calcium and magnesium thus formed are collected on a filter, 
washed, dissolved in a drop or two of hydrochloric acid; chloride 
of ammonium, ammonia, and carbonate of ammonium are added, 
and the mixture boiled and filtered ; any calcium originally present 
will then remain insoluble as carbonate of calcium, while any mag- 
nesium will be precipitated from the filtrate as ammonio-magnesium 
phosphate on the addition of phosphate of sodium, the mixture being 
also well stirred The chief portion of excreted phosphates is car- 
ried off by the feces, that remaining in the urine being kept in solu- 
tion by the influence of acid phosphate of sodium, and, frequently, 
lactic acid. Occasionally, an hour or two after a heart v meal the 
urine becomes sufficiently alkaline for the phosphates to be deposited, 
and the urine when passed is turbid from their presence. The am- 
moniacal constituent of the magnesium salt does not occur nor- 
mally, but is produced from urea as soon as urine becomes alka- 
line. 



564 



MORBID URINE. 



Examination of Urinary Sediments. 
"Warm the sediment with the supernatant urine and filter. 



Insoluble. 




Soluble. 


Phosphates, oxalate of calcium, and uric 


Urates— of ammonium , 


acid. 




calcium, or sodium, 


Warm with acetic acid, 


and filter. 


chiefly the latter. 






They are redeposited 


Insoluble. 


Soluble. 


as the liquid cools, and 
if sufficient in quantity 


Oxalate of calcium ana uric 


Phosphates. 


may be further exam- 


acid. 


Add ammo- 


ined for ammonium, 


Warm with hydrochloric 


nia, white ppt. 


calcium, sodium, and 


acid, filter. ' 


= phosphate 


the uric radical by the 




of calcium, or 
ammonio-mag- 


appropriate tests. 








Insoluble. 


Soluble. 


nesium phos- 
phate, or both. 




Uric acid. 


Oxalate of 






Apply mu- 


calcium. 






rexid test (p. 


May be pre- 






358). 


cipitated by 
ammonia. 







Oxalate of calcium is seldom met with in excessive amounts, but 
very often in small quantities mixed with phosphates. 

In one case of oxaluria the whole urine excreted by a patient in 
twenty-four hours furnished to the author only two-thirds of a grain 
of oxalate of calcium. 

Free uric acid is in most cases distinctly crystalline, and nearly 
always of a yellow, red, or brown color. 

Artificial Sediments. — For educational practice artificial deposits 
may be obtained as follows : — 1. Rub up in a mortar a few grains of 
serpent's excrement (chiefly urate of ammonium) with an ounce or 
two of urine ; this represents a sediment of urates. 2. Add a few 
drops of solution of chloride of calcium and of phosphate of sodium 
to urine 5 the deposit may be regarded as one of phosphates. 3. To 
an ounce or two of urine add very small quantities of chloride of 
calcium and oxalate of ammonium ; the precipitate is oxalate of cal- 
cium. 4. To urine acidulated by hydrochloric acid add a little ser- 
pent's excrement ; the sediment is uric acid. 

Other deposits than the foregoing are occasionally observed. Thus 
hippuric acid (HC 9 H 8 N0 3 ), a normal constituent of human urine, 
and largely contained in the urine of herbivorous animals, is some- 
times found associated with uric acid in urinary sediment, especially 
in that of patients whose medicine contains benzoic acid (p. 335). 



UEINARY SEDIMENTS. 565 

Its appearance, as observed by the aid of the microscope, is charac- 
teristic — namely, slender, four-sided prisms, having pointed ends. 
Cystin (C 3 H 7 HS0 2 ) (from tcvang, kustis, a bladder, in allusion to its 
origin) rarely occurs as a deposit in urine. It is not soluble in 
warm urine or dilute acetic acid, and scarcely in dilute hydrochloric 
acid, hence would be met with in testing for free uric acid. It is 
very soluble in ammonia, recrystallizing from a drop of the solu- 
tion placed on a piece of glass in characteristic microscopic six- 
sided plates. Organized sediments may be due to the corpuscles 
of pus, mucus, or blood, fat-globules, spermatozoa, cylindrical casts 
of the tubes of the kidneys, epithelial cells from the walls of the 
bladder, or foreign matters, such as fibres of wood, cotton, small 
feathers, dust, starch ; these are best recognized by the microscope, 
as will be seen by the following paragraphs and figures on the 
microscopic appearances of both crystalline and organized urinary 
sediments. 

Microscopic Examination of Urinary Sediments. 

Urine containing insoluble matter is usually more or less opaque. 
For a microscopical examination a few ounces should be set aside in 
a conical test-glass for an hour or two, the clear supernatant urine 
poured off from the sediment as far as possible, a small drop of the 
residue placed on a slip of glass and covered with a piece of thin 
glass, and examined under the microscope with different magnifying 
powers. 

[The respective appearances of the various crystalline and or- 
ganized matters are given in the following figures, which were 
kindly drawn by H. B. Brady, F. R. S., from natural specimens (as 
seen with a two-third inch objective and No. 1 eye-piece — i. e., mag- 
nified 60 diameters) in the collections of St. Bartholomew's Hos- 
pital, Dr. Sedgwick, W. W. Stoddart, F. C. S., Mr. Waddington, and 
the author.] 

Uric Acid occurs in many forms, most of which are given in the 
first two figures. Flat, more or less oval crystals, sometimes at- 
tached to each other, their outline then resembling an 8, a cross, or 
a star, are common. Single and grouped quadratic prisms, aigrettes, 
spicula, and crystals recalling dumb-bells are met with. From urine 
acidulated by hydrochloric acid square crystals, two opposite sides 
smooth and two jagged, are generally deposited ; acidulated by 
acetic acid, more typical forms are obtained. A drop of solution 
of potash or soda placed on a glass slip will dissolve a deposit of 
uric acid, a drop of any acid reprecipitating it in minute but charac- 
teristic crystals. 

Cystin is very rarely met with as a urinary deposit ; that from 
which the figure was taken was found in the urine of a patient in 
St. Bartholomew's Hospital. Lamella) of cystin always assume an 
hexagonal character, but the angles are sometimes ill defined anil 
the plates superposed ; in the latter case, a drop of solution o( am- 
monia placed on the glass at once dissolves the deposit, well-marked 
six-sided crystals appearing as the drop dries up. 
48 



566 



MORBID UEINE. 



Fig. 51. 



Fig. 52. 




Uric Acid. Uric Acid. 

Triple Phosphate (phosphate of magnesium and ammonium) is 
deposited as soon as urine becomes alkaline, the ammoniacal con- 
stituent being furnished by the decomposition of urea. It occurs 

Fig. 54. 




Cystin. Triple Phosphate. 

in large prismatic crystals, forming a beautiful object when viewed 
by polarized light ; sometimes also in ragged stellate or arborescent 
crystals resembling those of snow. Both forms may be artificially 
prepared by adding a small lump of carbonate of ammonium to a 
few ounces of urine and setting aside in a test-glass. 

Amorphous deposits are either earthy phosphates (a mixture of 
phosphates of magnesium and calcium) or urates (of calcium, mag- 
nesium, ammonium, potassium, or sodium — chiefly the latter). They 
may be distinguished by the action of a drop of acetic acid placed 
near the sediment on the glass slip, the effect being watched under 



URINARY SEDIMENTS. 



567 



the microscope ; phosphates dissolve, while urates gradually assume 
characteristic forms of uric acid. Urates redissolve when warmed 
with the supernatant urine. 

Urates of Sodium and Magnesium, though generally amorphous, 
occasionally take a crystalline form — bundles or tufts of small 
needles — as shown in the cut. 

Oxalate of Calcium commonly occurs in octahedra requiring high 
magnifying-power for their detection. The crystals are easily over- 
looked if other matters are present, but are more distinctly seen after 
phosphates have been removed by acetic acid. In certain aspects the 
smaller crystals look like square plates traversed by a cross. A 
dumb-bell form of this deposit is also sometimes seen, resembling 
certain forms of uric acid and the coalescing spherules of a much 
rarer sediment, carbonate of calcium. Oxalate of calcium is insol- 
uble in acetic, but soluble in hydrochloric, acid. The octahedra are 
frequently met with in the urine of persons who have partaken of 
garden rhubarb ; the crystals may often be deposited artificially (ac- 
cording to Waddington) by dropping a fragment of oxalic acid into 
several ounces of urine and setting aside for several hours. 



Fig. 55. 



Fig. 56. 




Urates. ") Oxalate of Calcium. | Carbonate of Calcium. Hippuric Acid. 

a, of Sodium ; > 

b, of Magnesium, j 

Carbonate of Calcium is rarely found in the urine of man, but 
frequently in that of the horse and other herbivorous animals. Hu- 
man urine containing carbonate of calcium often reddens litmus- 
paper ; and it is only after the removal, on standing, of the excess of 
carbonic acid that the salt is deposited. It consists of minute spher- 
ules, varying in size, the smaller ones often in process of coalescence. 
The dumb-bell form thus produced is easily distinguished from simi- 
lar groups of uric acid or oxalate of calcium by showing a black 
cross in each spherule when viewed by polarized light. Acetic acid 
dissolves carbonate of calcium, liberating carbonic acid gas, with 
visible effervescence (under the microscope) if the slide has been pre- 
viously warmed and a group of crystals be attacked. 

Hippuric Acid. — The pointed rhombic prisms and acicular ens- 



568 



MOEBID URINE. 



tals are characteristic and easily recognized. The broader crystals 
may possibly be mistaken for triple phosphate, and the narrower for 
certain forms of uric acid ; but insolubility in acetic acid distin- 
guishes them from the former, and solubility in alcohol from the 
latter. These tests may be applied while the deposit is under 
microscopic observation. An alcoholic solution of hippuric acid 
evaporated to dryness, and the residue treated witL water, gives a 
solution from which characteristic crystalline forms of hippuric acid 
may be obtained on allowing a drop to dry upon a slip of glass. 

The organized deposits in urine entail greater care in their deter- 
mination, and usually require a higher magnifying-power for their 
proper examination, than those of crystalline form. The figures are 
drawn to 230 diameters. The following notes will assist the observer : — 

Casts of uriniferous tubuli are fibrinous masses of various forms, 
and often of considerable length — sometimes delicate and trans- 
parent, occasionally granular, and often beset with fat-globules. 
Epithelial debris are frequently present in urine in the form of 
nucleated cells, regular and oval when full, but angular and un- 
symmetrical when partially emptied of their contents — sometimes 
perfect, but more frequently a good deal broken up. 



Fig. 57. 



Fig. 58. 




Epithelial Cells and Tubuli. 



Blood-Corpuscles. 



Blood is easily recognized. Urine containing it is high-colored, 
and the corpuscles appear under the microscope as reddish circular 
disks, either single or laid together in strings resembling piles of 
coin. Their color and sometimes smaller size serve to distinguish 
them from pus-corpuscles. In doubtful cases a minute drop of 
blood taken from a finger by help of a needle should be diluted 
with water and used for comparison. After urine containing blood 
lias stood for some time the corpuscles lose their regular outline and 
become angular. (See a in the figure.) Day of Geelong tests for 
blood in urine or in stains on clothing by emplo}*ing a recently-pre- 
pared alcoholic solution of the inner unoxidizcd portions of guaiacum 
resin and an aqueous or ethereal solution of peroxide of hydrogen, 
when a blue color results. In the case of urine, add to about a 



URINARY SEDIMENTS. 



569 



quarter of an ounce in a test-tube nearly as much of the ethereal^ 
fluid, and then two or three drops of the guaiacum tincture ; on 
gently agitating the tube a bluish-green layer appears at the junc- 
tion of the fluids if blood is present. "If the stain is on a dark- 
colored fabric, the parts moistened by the fluids may be pressed 
with white blotting-paper, when blue impressions will be obtained. 
Contact with many substances causes the blue reaction or oxida- 
tion of guaiacum; the peculiarity of blood is that it does not 
produce this effect unless peroxide of hydrogen or a similar ' auto- 
some' liquid is present. Bodies such as permanganate of potassium, 
whose oxygen is, apparently, in the form of ozone, also give rise to 
a blue color with guaiacum ; peroxide of hydrogen and other com- 
pounds whose oxygen is in the opposite, positive, or, according to 
Schonbein, antagonistic condition, produce no such effect. It would 
seem as if blood or some other constituent of blood has the power 
of converting positive into negative oxygen, and thus bring about 
an effect which negative oxygen alone is able to produce ; for of all 
substances which, like blood, do not alone cause guaiacum to become 
blue, blood is the only one that so affects ' antozonides ' (themselves 
inactive) as to enable them to act as ozonides — that is, to oxidize the 
guaiacum. Both the venous and arterial fluid from any red-blooded 
animal will produce this blue reaction. Fruit-stains are darkened 
by ammonia, which does not alter the color of blood. Iron-stains 
or iron-mould yields no color to water, whereas the red coloring-mat- 
ter of blood is soluble in water. The peroxide of hydrogen should 
be free from more than a trace of acid." 

The blood-corpuscles of ordinary animals are much smaller than 
those of man, but a ^ or -^ of 

an inch lens is necessary for Fig. 59. 

proper differentiation (J. G. 
Richardson). 

Pus and Mucus. — Purulent 
urine deposits, on standing, a 
light-colored layer, easily dif- 
fused through the liquid by 
shaking. Acetic acid does not 
dissolve the sediment, and so- 
lution of potash, of official 
strength, converts it into a 
gelatinous mass. Under the 
microscope, pus-corpuscles ap- 
pear rounded and colorless, 
rather larger than blood-disks, 
and somewhat granular on the 
surface. They generally show 
minute nuclei, which are more 
distinctly seen after treatment with acetic acid. (See the portion of 
the figure marked a.) Mucus possesses no definite microscopic cha- 
racters, but commonly has imbedded in it pus, epithelium, and air- 
bubbles. Mucus is coagulated in a peculiar and characteristic manner 
by acetic acid; and this reaction, together with the ropy appear- 
48* 




l'us-Corpusclee 



570 



MORBID URINE. 



ance it imparts to urine, prevents its being confounded with pus. 
Day's test for pus consists in adding a drop or two of oxidized 
tincture of guaiacum to the urine or other liquid, when a clear blue 
color is produced. It is necessary to moisten dry pus with water 
before applying the test. The 
Fig. 60. test-liquid is made by exposing 

a saturated alcoholic solution of 
guaiacum to the air until it has 
absorbed a sufficient quantity of 
oxygen to give it the property 
of turning green when placed 
in contact with iodide of potas- 
sium. Day's test for mucus 
consists in the application, first, 
of oxidized tincture of guaiac- 
um, which by itself undergoes 
no change in the presence of 
mucus, and then in the addition 
of carbolic acid or creasote, 
which quickly changes the color 
of the guaiacum to a bright 
Fat-Globules. blue. Neither carbolic acid 

nor creasote alone will render 
guaiacum blue. In testing for mucus on cloths or when it is mixed 
with blood, it is necessary to use the carbolic acid pure, but when 
the mucus is in a liquid state it is better to use carbolic acid diluted 
with alcohol. 

Saliva. — Saliva is an aqueous fluid containing less than 1 per 




Fig. 61. 



Fig. 62. 




Spermatozoa. Sarcina ventriculi. 

cent, of solid matter, of which one-third is an albumenoid substance 
termed ptyalin (from Trrvelov, spittle), a body that has power of con- 
verting starch into dextrin and grape-sugar. Alkaline salts, includ- 
ing a trace of sulphocyanate of potassium, and calcareous compounds 
are also present. 



URINARY SEDIMENTS. 571 

Day's test for saliva in urine, etc. is similar to that for mucus, 
with the exception that the blue reaction produced by the oxidized 
tincture of guaiacum and alcoholic solution of carbolic acid is highly 
intensified by the addition of Robbing's aqueous or ethereal solution 
of peroxide of hydrogen. 

Fatty matter occurs either as minute globules partially diffused 
through the urine (as shown at a, Fig. 60) or in more intimate emul- 
sion (as at b). When present in larger quantity it collects as a sort 
of scum on the surface after standing. 

Spermatozoa are liable to escape notice on account of their small 
size and extreme transparency. Suspected urine should be allowed 
to settle some hours in a conical test-glass, and the drop at the bot- 
tom examined under a high power. The drawing (Fig. 61) shows 
their tadpole-like appearance. 

Sarcina ventriculi is a bacterium of a very rare occurrence in urine, 
though not unfrequent in vomited matters. The upper figures (a, 
Fig. 62) are copied from Dr. Thudichum's drawing (from urine) ; 
the larger fronds (6) are from vomited matter. 

Extraneous bodies, such as hair, wool, or fragments of feathers, 
are often found in urinary deposits, and ludicrous mistakes have 
been made by observers not on their guard in respect to such casual 
admixtures. 

Examination of Urinary Calculi. 

The term calculus is the diminutive of calx, a lime- or chalk- 
stone. 

Knowledge of the composition of a calculus or urinary deposit 
affords valuable diagnostic aid to the physician ; hence the import- 
ance of a correct analysis of these substances. 

Nature of Calculi. — Urinary calculi have the same composition 
as unorganized urinary sediments. They consist, in short, of sedi- 
ments that have been deposited slowly within the bladder, particle 
on particle, layer on layer, the several substances becoming so com- 
pact as to be less easily acted on by reagents than when deposited 
after the urine has been passed — the urates less readily soluble in 
warm water, the calcic phosphate insoluble in acetic acid until it 
has been dissolved in hydrochloric acid and reprecipitated by an 
alkali. 

Preliminary Treatment. — If the calculus is whole, saw it in two 
through the centre, and notice whether it is built up of distinct 
layers or apparently consists of one substance. If the latter, use 
about a grain of the sawdust for the analysis; if the former, care- 
fully scrape off portions of each layer and examine them separately. 
If the calculus is in fragments, select fair specimens of about half 
a grain or a grain each, and reduce to a fine powder by placing on 
a hard surface and crushing under the blade of a knife. 

Analysis. — Commence the analysis by heating a portion, 
about the size of a pin's head, on platinum foil, in order to 
ascertain whether organic matter, inorganic matter, or both are 



572 



MORBID URINE. 



present. If both, the ash is examined for inorganic substances, 
and a fresh portion of the calculus for uric acid by the murexid 
test. (In the absence of uric acid any slight charring may be 
considered to be due to indefinite animal matter.) If composed 
of organic matter only, the calculus will in nearly all cases be 
uric acid, the indications being confirmed by applying the mu- 
rexid test, in a watch-glass, to another fragment half the size 
of a small pin's head. If inorganic only, the ash on the plati- 
num foil may be examined for phosphates, and a separate por- 
tion of the calculus for oxalates. Even a single drop of liquid 
obtained in any of these experiments may be filtered by placing 
it on a filter not larger than a sixpence and previously moist- 
ened with water, and adding three or four drops of water one 
after the other as each passes through the paper ; or a drop of 
mixture may be placed on a fragment of damped filter-paper on 
a glass slide, the latter then tilted, and a clear drop be drained 
off from the paper on to the slide ready for the addition of a 
reagent. If the calculus is suspected to contain more than 
one substance, boil about half a grain of the powder in half a 
test-tubeful of distilled water for a few minutes, and pour it on 
a small filter; then proceed according to the following 
Table :— 



Insoluble. 

Phosphates, oxalate of calcium, and free 

uric acid. 

Boil with two or three drops of hydrochloric 

acid, and filter. 



Insoluble. 

Uric acid. 
Apply the 

murexid 
test 

(p. 358). 


Soluble. 

Phosphates and oxalate of 

calcium. 

Add excess of ammonia, and then 

excess of acetic acid ; filter. 



Insoluble. 

Oxalate of 
calcium. 



Soluble. 

Phosphates. 
They may be repre- 
cipitated by ammonia. 



Soluble. 

Urates. 
These will prob- 
ably be redepos- 
ited as the solution 
cools. Small quan- 
tities may be de- 
tected by evaporat- 
ing the solution to 
dryness. They are 
tested for ammo- 
nium, sodium, cal- 
cium, and the uric 
radical by the ap- 
propriate reagents. 



Varieties of Calculi. — Calculi composed entirely of uric acid are 
common ; a minute portion heated on platinum foil chars, burns, 



QUESTIONS AND EXERCISES. 573 

and leaves scarcely a trace of ash. The phosphates frequently 
occur together, forming what is known as the fusible calculus from 
the readiness with which a fragment aggregates, and even fuses to 
a bead, when heated on a loop of platinum wire in the blowpipe- 
flame/ The phosphates may, if necessary, be further examined by 
the method described in connection with urinary deposits. Oxalate 
of calcium often occurs alone, forming a dark-colored calculus hav- 
ing a very rough surface, hence termed the mulberry calculus. 
Smaller calculi of the same substance are called, from their appear- 
ance, hempseed calculi. Calculi of cystin are rarely met with. 
Xanthin (from t-avdbc, xanthos, yellow, in allusion to the color it 
yields with nitric acid) less often occurs as a calculus. The earthy 
concretions, or chalk-stones, which frequently form in the joints of 
gouty persons are composed chiefly of urates, the sodium salt being 
that most commonly met with. Gall-stones, or biliary calculi, occa- 
sionally form in the gall-bladder ; they contain cholesterin (from 
%oM/, chole, bile, and orepebc, stereos, solid), a fatty substance of 
alcoholoid constitution, soluble in rectified spirit or ether, and crys- 
tallizing from such solutions in well-defined, square, scaly crystals. 
Phosphatic and other calculi of many pounds weight are occasion- 
ally found in the stomach and larger intestines of animals. 



QUESTIONS AND EXERCISES. 

907. In breathing, how much carbon (in the form of carbonic acid 
gas) is exhaled from the lungs every twenty-four hours ? 

908. How may the presence of carbonic acid gas in expired air be 
demonstrated ? 

909. Mention an experiment showing the escape of moisture from 
the lungs during breathing. 

910. State the method of testing for albumen in urine. 

911. Give the test for sugar in urine. 

912. What is the average composition of healthy urine? 

913. Give the tests for urea. 

914. Write the rational formulas of some compound ureas in which 
methyl or ethyl displaces hydrogen. 

915. Describe an artificial process for the production of urea, 
giving equations. 

916. Sketch out a plan for the chemical examination of urinary 
sediments. 

917. A deposit is insoluble in the supernatant urine or in acetic 
acid ; of what substance may it consist? 

918. Which compounds arc indicated when a deposit redissolves 
on warming it with the supernatant urine? 

919. Name the salts insoluble in warmed urine, but dissolved on 
the addition of acetic acid. 

920. Mention the chemical characters of cystin. At what stage 
of analysis would it be recognized? 



574 OFFICIAL GALENICAL PKEPAKATIONS. 

921. Describe the microscopical appearance of the following urin- 
ary deposits : Uric acid, cystin, triple phosphate, earthy phosphates, 
urates, oxalate of calcium, carbonate of calcium, hippuric acid, tube- 
casts, epithelial debris, blood, pus, mucus, fat, spermatozoa, sarcina, 
extraneous bodies. 

922. How are Day's tests for blood, pus, and saliva applied? 

923. What is the general, physical, and chemical nature of urinary 
calculi ? 

924. How are urinary calculi prepared for chemical examination? 

925. Draw out a chart for the chemical examination of urinary 
calculi. 

926. Why is the "fusible calculus" so called? and what is its 
composition ? 

927. State the characters of "mulberry" and " hempseed " cal- 
culi. 

928. What are the "chalk-stones" of gout and "gall-stones" or 
" biliary calculi" ? 



THE GALENICAL PREPARATIONS OF THE 
PHARMACOPOEIAS. 

The preparation of Abstracts, Cerates, Confections, Decoc- 
tions, Elixirs, Enemas, Extracts, Glycerins, Infusions, Inhala- 
tions, Juices, Liniments, Lozenges or Troches, Mixtures, Oint- 
ments, Pills, Plasters, Poultices, Powders, Spirits, Suppositories, 
Syrups, Tinctures, Triturations, and Wines includes a number 
of mechanical rather than chemical operations, and belongs to 
the domain of pure Pharmacy. The medical or pharmaceutical 
pupil will have had ample opportunity of practically studying 
those compounds before working at experimental chemistry, and 
will probably have prepared many of them according to the 
directions of the Pharmacopoeias ; if not, he is referred to the 
pages of the last edition of those works for details. 

Among the extracts of the British Pharmacopoeia, however, 
there are five (namely, those of Aconite, Belladonna, Hemlock, 
Henbane, and Lettuce) which are not simply evaporated infu- 
sions, decoctions, or tinctures, like most others, but are evapor- 
ated juices from which vegetable albumen, the supposed source 
of fermentation and decay, has been removed, and chlorophyll 
(the green coloring-mater of plant-juice) retained, practically 
unimpaired in tint. For educational practice either of the 
above-named five raw materials may be employed ; but in order 



OFFICIAL GALENICAL PREPARATIONS. 575 

that attention may be concentrated on the process by which 
the extracts are prepared, rather than on any one of the ex- 
tracts themselves, it suffices to make an extract of some ordi- 
nary green vegetable, such as cabbage or turnip-tops. Bruise 
the green leaves of a good-sized cabbage in a mortar, and press 
out the juice : heat it gradually to 130° F., and remove the 
green flocks of chlorophyll which separate, by filtration through 
calico. When the liquor has all passed through the filter, set 
the chlorophyll aside for a time, heat the strained liquor to 
200° F. to coagulate albumen ; remove the latter by filtration 
and throw it away ; evaporate the filtrate by a water-bath to 
the consistence of thin syrup ; then add to it the chlorophyll, 
and, stirring the whole together assiduously, continue the 
evaporation at a temperature not exceeding 140° F. until the 
extract is of a suitable consistence for forming pills. A higher 
temperature than that indicated would cause the alteration of 
the chlorophyll to a dark-brown substance, any such extract 
used in pharmacy no longer having the green tint which cus- 
tom and the British Pharmacopoeia demand. 



QUESTIONS AND EXERCISES. 

929. Enumerate the different classes into which official galenical 
preparations may be divided. 

930. Describe the general process for the preparation of green 
extracts : — 

Aconite. Hemlock. 

Belladonna. Henbane. 

Lettuce. 

931. Why is vegetable albumen excluded in the preparation of 
green extracts? 

932. How may chlorophyll be removed from vegetable juices, and 
again be introduced into their evaporated residues, without destroy- 
ing its color? 

933. For what reason is exposure of chlorophyll to a boiling tem- 
perature avoided in the manufacture of green extracts ? 



576 QUANTITATIVE ANALYSIS. 



THE CHEMICAL PPEPAKATIONS OF THE 
PHARMACOPOEIAS. 

The process by which every official chemical substance is 
prepared has already been described, and the strict chemical 
character of the processes illustrated by experiments and ex- 
plained by aid of equations. Should the reader, in addition, 
desire an intimate acquaintance with those details of manipu- 
lation on which the successful and economic manufacture of 
chemical substances depends, he is advised to prepare, if he 
has not done so already, a few ounces of each of the salts men- 
tioned in the Pharmacopoeias or commonly used in Pharmacy. 
An additional guide in these operations will be the Pharmaco- 
poeia itself. 

The production of many chemical and galenical substances 
on a commercial scale can only be successfully carried on in 
manufacturing laboratories and with some knowledge of the 
circumstances of supply and demand, value of raw material and 
of by-products, etc. ; for the technical preparation of such sub- 
stances requires much knowledge beyond even a thorough 
acquaintance with Chemistry. Still, in the present day, com- 
mercial Chemistry and Pharmacy can best hope for success 
when founded on the working out of abstract scientific princi- 
ples. The problem of manufacturing success is now only solved 
with certainty by sound and wisely-applied science. 



Memorandum. — The next subject of experimental study will 
be determined by the nature of the student's future pursuits. 
In most cases the operations of quantitative analysis will engage 
attention. These should be of a volumetric and gravimetric 
character ; for details concerning them see the following pages. 



QUANTITATIVE ANALYSIS. 

INTRODUCTORY REMARKS. 

General Principles. — The proportions in which chemical sub- 
stances unite with each other in forming compounds are definite 



QUANTITATIVE ANALYSIS. 577 

and invariable (p. 47). Quantitative analysis is based on this law. 
When, for example, aqueous solutions of a salt of silver and a chlo- 
ride are mixed, a white curdy precipitate is produced containing 
chlorine and silver in atomic proportions ; that is, 35.4 parts of chlo- 
rine to 107.7 of silver. No matter what the chloride or what the 
salt of silver, the resulting chloride of silver is invariable in compo- 
sition. The formula AgCl is a convenient picture of this compound 
in these proportions. The weight of a definite compound being 
given, therefore, the proportional amounts of its constituents can 
be ascertained by simple calculation. Suppose, for instance, 8.53 
parts of chloride of silver have been obtained in some analytical 
operation ; this amount will contain 2.11 parts of chlorine and 6.42 
of silver ; for if 143.1 (the molecular weight) of chloride of silver 
contain 35.4 (the atomic weight) of chlorine, 8.53 of chloride of sil- 
ver will be found to contain 2.11 of chlorine : — 

143.1 : 35.4 : : 8.53 : x. 



143.1)301.962(2.11 
286.2 
15.76 
14.31 



1.452 
1.431 

21 « = 2.11. 

And if 143.1 of chloride of silver contain 107.7 of silver, 8.53 of 
chloride of silver will contain very nearly 6.42 of silver. To ascer- 
tain, for example, the amount of silver in a substance containing, 
say, nitrate of silver, all that is necessary is to take a weighed quan- 
tity of the substance, dissolve it, precipitate the whole of the silver 
by adding hydrochloric acid or other chloride till no more chloride of 
silver falls, collect the precipitate on a filter, wash, dry, and weigh. 
The amount of silver in the dried chloride, ascertained by calcula- 
tion, is the amount of silver in the quantity of substance on which 
the operation was conducted ; a rule-of-three sum gives the quantity 
per cent., the form in which the results of quantitative analysis are 
usually stated. Occasionally a constituent of a substance admits of 
being isolated and weighed in the uncombined state. Thus the 
amount of mercury in a substance may be determined by separating 
and weighing the mercury in a metallic condition ; if occurring as 
calomel (HgCl) or corrosive sublimate (HgCl 2 ), the proportion o( 
chlorine may then be ascertained by calculation (He =199.7; 
CI = 35.4). ' 

Nature of Gravimetric Quantitative Analysis.— As above stated, 
a body may be isolated and weighed, and its quantity thus ascertained, 
or it may be separated and weighed in combination with another body 
49 



578 QUANTITATIVE ANALYSIS. 

whose combining proportion is well known ; this is quantitative anal- 
ysis by the gravimetric method. 

Nature of Volumetric Quantitative Analysis. — Volumetric opera- 
tions depend for success on some accurate initial gravimetric opera- 
tion. A weighed amount of a pure salt is dissolved in a given volume 
of water or other fluid, and thus forms a standard solution. Accu- 
rately measured quantities of such a solution will obviously contain 
just as definite amounts of the dissolved salt as if those amounts were 
actually weighed in a balance, a ud, as measuring occupies less time 
than weighing, the volumetric operations can be conducted with great 
economy of time as compared with the corresponding gravimetric 
operations. Quantitative analysis by the volumetric method consists 
in noting the volume of the standard liquid required to be added to 
the substance under examination before a given effect is produced. 
Thus, for instance, a solution of nitrate of silver of known strength 
may be used in experimentally ascertaining an unknown amount of 
chlorine in any substance. The silver solution is added to a solu- 
tion of a definite quantity of the substance until flocks of chloride 
of silver cease to be precipitated : every 107.7 parts of silver added (or 
169.7 of nitrate of silver: Ag— 107.7, X = 14, 3 =48; total 169.7) 
indicates the presence of 35.4 of chlorine or an equivalent quantity 
of any chloride. The preparation of standard solutions, such as 
that of nitrate of silver, to which allusion is here made, requires 
considerable care, but when made certain analyses can, as already 
indicated, be executed with far more rapidity and ease than by 
gravimetric processes. 

Quantitative Determination of (a) Atmospheric Pressure, (b) Tem- 
perature, and (c) Weight. — The quantitative analysis of solids and 
liquids often involves quantitative determinations of atmospheric 
pressure, temperature, and weight. These processes will now be 
explained, after which an outline of volumetric and gravimetric 
quantitative analysis will be given. The scope of this work pre- 
cludes any attempt to describe all the little mechanical details ob- 
served by quantitative analysts ; essential operations, however, are 
so fully treated that expert manipulators will meet with little 
difficulty. 

Quantitative Determination of Atmospheric Pressure. 

The Barometer. — The analysis of gases and vapors involves de- 
terminations of the varying pressure of the atmosphere as indicated 
by the barometer (from j3dpog, baros, weight, and /nerpov, metron, 
measure). 

TJie ordinary mercurial barometer is a glass tube 33 or 34 inches 
long, closed at one end, filled with mercury, and inverted in a small 
cistern or cup of mercury (fig. 63). The mercury remains in the 
tube, owing to the weight or pressure of the atmosphere on the ex- 
posed surface of the liquid, the average height of the column being 
nearly 30 inches. In the popular form of the instrument, the wheel- 
barometer, the cistern is formed by a recurvature of the tube (fig. 
64) ; on the exposed surface of the mercury a float is placed, from 
which a thread passes over a pulley and moves an index whenever 



TEMPERATURE. 



579 



the column of mercury rises or falls. As supplied to the public, 
these barometers are usually enclosed in ornamental frames with 
thermometers attached. In the wheel- 
Fig. 63. barometer the glass tube and contained Fig, 64. 
y- v column of mercury are altogether en- i**'"*"* 
closed, the index alone being visible. 
In the other variety the upper end of 
the glass tube and mercurial column 
\ 11-30/ are exposed, and the height of the 
mercury is ascertained by direct ob- 
servation. 

The aneroid barometer (from o, «, 
without, and vrjpbc, neros, fluid) con- 
sists of a small, shallow, vacuous metal 
drum, the sides of which approach 
each other when an increase of atmo- 
spheric pressure occurs, their elasticity 
enabling them to recede toward their 
former position on a decrease of pres- 
sure. This motion is so multiplied 
and altered in direction by levers, etc. 
as to act on a hand traversing a plate > 
on which are marked numbers corre- \ 
sponding with those showing the height * 
of the mercurial column of the ordi- 
nary barometer by which the aneroid 
~\ *&> /' was adjusted. The Bourdon barometer 
\.S (from the name of the inventor) is a 

Barometer.- modified aneroid, containing, in the 
place of the round metal box, a flat- 
tened vacuous tube of metal bent nearly to a circle, 
ters are also useful for measuring the pressure in steam-boilers, etc. 
Under the name of pressure-gauges they are sold to indicate pres- 
sure of 500 pounds and upward per square inch. From their porta- 
bility (they can be made of 1 to 2 inches in diameter and 1 inch 
thick) they are excellent companions for travellers wishing to know 
the height of hills, mountains, and other elevations. 

For further information concerning the influence of pressure on 
the volume of a gas or vapor see page 547 ; and for descriptions of 
the methods of analyzing gases refer to Ganot's Physics (translated 
by Atkinson), Miller's Chemical Physics, and "Analysis of Gases '* 
in Watt's Dictionary of Chemistry. 

Quantitative Determination of Temperature. 

General Principles. — As a rule, all bodies expand on the addition 
and contract on the abstraction ol heat, the alteration in volume 
being constant and regular for equal increments or decrements ol' 
temperature. The extent of this alteration in a given substance, 
expressed in parts or degrees, constitutes the usual method ol' in- 
telligibly stating, with accuracy, precision, and minuteness, a par- 
ticular condition of warmth or temperature — that is, of sensible 




These barom- 



580 QUANTITATIVE ANALYSIS. 

heat. The substance commonly employed for this purpose is mer- 
cury, the chief advantages of which are that it will bear a high tem- 
perature without boiling, a low temperature without freezing, does 
not adhere to glass to a sufficient extent to "wet 1 ' the sides of any 
tube in which it may be enclosed, and, from its good conducting- 
power for heat, responds rapidly to changes of temperature. Plati- 
num, earthenware, alcohol, and air are also occasionally used for 
thermometric purposes. 

The Thermometer. — The construction of an accurate ther- 
mometer is a matter of great difficulty, but the following are 
the leading steps in the operation : — Select a piece of glass 
tubing having a fine capillary (cajpillus, a hair) bore and about 
a foot long ; heat one extremity in the blowpipe-flame until the 
orifice closes and the glass is sufficiently soft to admit of a 
bulb being blown ; heat the bulb to expel air, immediately 
plunging the open extremity of the tube into mercury ; the 
bulb having cooled, and some mercury having entered and 
taken the place of expelled air, again heat the bulb and tube 
until the mercury boils and its vapor escapes through the bore 
of the tube : again plunge the extremity under mercury, which 
will probably now completely fill the bulb and tube. When 
cold the bulb is placed in melting ice. The top of the column 
of mercury in the capillary tube should then be within an inch 
or two of the bulb ; if higher, some of the mercury must be 
expelled by heat ; if lower, more metal must be introduced as 
before. The tube is now heated near the open end and a portion 
drawn out until the diameter is reduced to about one-tenth. The 
bulb is next warmed until the mercurial column rises above the 
constricted part of the tube, which is then rapidly fused in the 
blowpipe-flame and the extremity of the tube removed. 

The instrument is now ready for graduation. The bulb is 
placed in the steam just above some rapidly boiling water (a 
medium having, cseter is paribus, an invariable temperature), and 
when the position of the top of the mercurial column is constant 
(the flask containing the water and steam being jacketed to pre- 
vent loss of heat by radiation), a mark is made on the tube 
by a scratching diamond or a file. This operation is repeated 
with melting ice (also a medium having an invariable tempe- 
rature). The space between these two marks is divided into a 
certain number of intervals termed degrees. Unfortunately, 
this number is not uniform in all countries : in England it is 
180, as proposed by Fahrenheit ; in France 100, as proposed 
by Celsius (the Centigrade scale), a number generally adopted 
by scientific men ; in some parts of the Continent the divisions 
are 80 for the same interval, as suggested by Reaumur. Which- 
ever be the number selected, similar markings should be con- 



THERMOMETRIC SCALES. 



581 



tinued beyond the boiling- and freezing-points as far as the 

length of the stem admits. They may be made on the stem 

itself or on any wood, metal, or 

Fig. 65. earthenware frame on which the 

Therinometric Scales. stem IS mounted. 

Thermometric Scales (fig. 65). — 
Gn the Centigrade (C.) and. Reau- 
mur (R.) scales the freezing-point of 
water is made zero, and the boiling- 
point 100 and 80 respectively 5 on 
the Fahrenheit (F.) scale the zero 
is placed 32 degrees below the con- 
gealing-point of water, the boiling- 
point of which becomes, consequent- 
ly, 212. Even on the Fahrenheit 
system, temperatures below the 
freezing-point of water are often 
spoken of as "degrees of frost;" 
thus 19 degrees as marked on the 
thermometer would be regarded as 
"13 degrees of frost." It is to be 
regretted that the freezing-point of 
water is not universally regarded 

as the zero-rpoint, and that the number of intervals between that and 

the boiling-point is not everywhere the same. 

The degrees of one scale are easily converted into those of another 

if their relations be remembered — namely : 180 (P.), 100 (C), 80 

(R.) ; or 18, 10, and 8 ; or, best, 9, 5, and 4. 



Fahrenheit. Centigrade. Reaumur. 



Formulas for the Conversion of Degrees of one Thermometric Scale 
into those of another. 



R = Reaumur. 

If above the freezing-point of water (32° F ; 0° C ; 0° R), 
F into C ..... . (D — 32) -^ 9 X 5. 

F " R (D — 32) -+■ 9 X 4. 

C " F D -=- 5 X 9 + 32. 

R " F D h- 4 X 9 + 32. 

but above 0° F (— 17°.77 C ; — 14°.22 R), 

— (32 — D) -+■ 9 X 5. 

_(3 2 -]))^9X4. 

32 — (D -s- 5 X 9. 

32 — (D -- 4 X 9. 

If below 0° F (— 17°.77 C ; — 14°.22 R), 

F into C ,,....— (D '+ 32) -*- 9 X 5. 
F « R , . , , : . -(I) j 32) h 9 X4. 

C « V — (1> -r 5 X 9) — 32. 

R « F — (I) -f- 4 X 9) — 32, 



If below freezin 
F into C 
F " R 

C " F 
R " F 



582 QUANTITATIVE ANALYSIS. 

For all degrees : 

C into R D-f-5X4. 

E " C D -J- 4 X 5. 

In ascertaining the temperature of a liquid the bulb of a 
thermometer is simply inserted and the degree noted. In de- 
termining the boiling-point also the bulb is inserted in the 
liquid, if a pure substance. In taking the boiling-point of a 
liquid which is being distilled from a mixture, the bulb of the 
thermometer should be near to but not beneath the surface. 

The " boiling-point " of a liquid is the temperature at which 
the elasticity of the vapor of the substance overcomes the 
atmospheric or other pressure to which the liquid is exposed. 
If the pressure is equal to 760 mm. (29.92 inches) of mercurv, 
water will boil at 100° C. (212° F.). The boiling-point of "a 
drop of a fluid is taken by introducing it into the closed ex- 
tremity of a small U-tube, the remaining portion of the closed 
limb being filled with mercury. The tube is lowered into a 
bath, the open limb being above the surface of the fluid of the 
bath. The bath is slowly and equally heated, and the boiling- 
point of the liquid, indicated by che mercury falling until it is 
level in the two limbs, taken by a thermometer whose bulb is 
close to the U-tube. 

The following are the boiling-points of a few substances met 
with in pharmacy : — 

Centigrade. Fahrenheit. 

Alcohol, absolute 78.3 173 

" 84 per cent 79.5 175 

" 49 per cent, (proof spirit) . . . 81.4 178.5 

" amylic 132.2 270 

Benzol 80.6 177 

Bromine 63.0 145.4 

Benzoic acid 239.0 462 

Carbolic acid 187.8 370 

Chloroform 61 142 

Ether (B. P.) (below) 40.5 105 

" pure 35 95 

Mercury in vacuo (as in a thermometer) . 304 580 

" in air (barom. at 30 inches) . . . 350 662 

Water (barom. at 29.92 inches) .... 100 212 

" ( " 29.33 " ) .... 99.5 211 

" ( " 28.74 " ) .... 99 210 

Saturated solutions of — 

Cream of tartar 101 214 

Common salt . r . . . . T . . , 106.6 224 

Sal ammoniac 113.3 236 

Nitrate of sodium . . . . . . ... 119 g46 

Acetate of sodium ........ 124.4 256 

Chloride of calcium ........ 179.4 355 



MELTING-POINTS. 583 

By " gentle heat," U. S. P., is meant any temperature between 
about 32° C. and 38° C. (about 90° and 100° F.). 

To Determine Melting-points of Fat. — Heat a fragment of 
the substance (spermaceti or wax, for example) till it liquefies, 
and then draw up a small portion into a thin glass tube about 
the size of a knitting-needle. Immerse the tube in cold water 
contained in a beaker, and slowly heat the vessel till the thin 
opaque cylinder of solid fat melts and becomes transparent ; a 
delicate thermometer placed in the water indicates the point of 
change to the fifth of a degree. Remove the source of heat 
and note the congealing-point of the substance ; it will be iden- 
tical with or close to the melting-point. 

Pyrometers. — Temperatures above the boiling-point of mer- 
cury are determined by ascertaining to what extent a bar of 
platinum or porcelain has elongated. The bar is enclosed in a 
cavity of a suitable case, a plug of platinum or porcelain placed 
at one end of the bar, and the whole exposed in the region the 
temperature of which is to be found. After cooling, the dis- 
tance to which the bar has forced the plug along the cavity is 
accurately measured and the corresponding degree of tempera- 
ture noted.. The value of the distance is fixed for low tempe- 
ratures by comparison with a mercurial thermometer, and the 
scale carried upward through intervals of equivalent length. 
Such thermometers are conventionally distinguished from ordi- 
nary instruments by the name pyrometer (from -up, pur, fire, 
and pixpov, metron, measure). 

The following are melting points of substances official in the 
British Pharmacopoeia : — 



Acetic acid, glacial 

" " " congeals at 

Benzoic acid 

Carbolic acid 

Oil of theobroma .... (about) 

Phosphorus 

Prepared lard (about) 

" suet 

Spermaceti (not under) 

White wax 

Yellow wax 

The order of fusibility of a few of the metals is as fol- 
io ays: — 



In decrees 


In degrees 


Centigrade. 


Fahrenheit 


8.9 


48 


1.1 


34 


120 


24S 


35 


95 


32 


90 


43.3 


110 


38 


100 


39.5 


L03 


38 


L00 


05.5 


150 


60 


140 



584 QUANTITATIVE ANALYSIS. 

In degrees In degrees 

Centigrade. Fahrenheit. 

Mercury — 39.4 — 39 

Potassium + 62.5 -j- 144.5 

Sodium 97.6 207.7 

Tin 227.8 442 

Bismuth 264 507 

Lead 325 617 

Zinc 411.6 773 

Antimony 621 1150 

Silver 1023 1873 

Copper 1091 1996 

Gold 1102 2016 

Cast iron 1530 2786 



QUESTIONS AND EXERCISES. 

934. On what fundamental laws are the operations of quantitative 
analysis based ? 

935. What is the general nature of gravimetric quantitative 
analysis? 

936. Describe the general principle of volumetric quantitative 
analysis. 

937. How are variations in atmospheric pressure quantitatively 
determined ? 

938. Explain the construction and mode of action of a mercurial 
barometer. 

939. In what respect does a wheel-barometer differ from an instru- 
ment in which the readings are taken from the top of the column of 
mercury ? 

940. Describe the principle of action of an aneroid barometer. 

941. On what general principles are thermometers constructed? 

942. What material is employed in making thermometers ? 

943. Why is mercury selected as a thermometric indicator? 

944. Describe the manufacture of a mercurial thermometer. 

945. How are thermometers graduated ? 

946. Give formulae for the conversion of the degrees of one ther- 
mometric scale into those of another, (a) when the temperature is 
above the freezing-point of water, (b) below 32° F., but above 0° F., 
and (c) below 0°. 

947. Name the degree C. equivalent to 60° F. 

948. What degree C. is represented by — 4° F. ? 

949. Mention the degree F. indicated by 23° C. 

950. Convert 100° R. into degrees C. and F. 

951. State the boiling-points of alcohol, chloroform, ether, mer- 
cury, and water on either thermometric scale. 

952. Describe the details of manipulation in estimating the melt- 
ing-point of fats. 

953. In what respect do pyrometers differ from thermometers? 



WEIGHTS AND MEASURES. 585 

954. Mention the melting-points of glacial acetic acid, oil of theo- 
broma, lard, snet, and wax. 

955. Give the fusing-points of tin, lead, zinc, copper, and cast- 
iron. 



Quantitative Determination of Weight. 

Definitions. 

All bodies, celestial and terrestrial, attract each other, the amount 
of attraction being in direct proportion to the quantity of matter of 
which they consist, and in inverse proportion to the squares of their 
distances. This is gravitation. When gravitation in certain direc- 
tions is exactly counterbalanced by gravitation in opposite directions, 
a body (e. g. the earth) remains suspended in space. Such a body 
in relation to other bodies has gravity, but not weight. Weight is 
the effect of gravity, being the excess of gravitation in one direction 
over and above that exerted in the opposite direction. Weight, 
truly, in any terrestrial substance is the excess of attraction which 
it and the earth have for each other over and above the attraction 
of each in opposite directions by the various heavenly bodies. But, 
practically, the weight of any terrestrial substance is the effect of 
the attraction of the earth only. Specific weight is the definite or 
precise weight of a body in relation to its bulk ; it is more usually 
but not quite correctly termed specific gravity — gravity belonging to 
the earth, and not, in any sensible degree, to the substance. 



QUESTIONS. 

956. What is understood by gravitation? 

957. State the difference between weight and gravity. 

958. Mention a case in which a body has gravity, but no apparent 
weight. 

959. Practically, what causes the weight of terrestrial substances? 



Weights and Measures. 



The Balance. — The balance used in the quantitative operations of 
analytical chemistry must be accurate and sensitive. The points of 
suspension of the beam and pans should be polished steel or agate 
knife-edges working on agate planes. It should turn easily and 
quickly, without too much oscillation, to ^y or ^j of a grain or 
-^ of a milligramme, when 1000 grains or 50 or 60 grammes are 
placed in each scale. (Grammes are weights of the metric system, 
a description of which is given on the next two or three pages.) The 
beam should be light and strong, capable of supporting a load of 
1500 grains or 100 grammes; its oscillations are observed by help 
of a long index attached to its centre, and continued downward tor 



~j9>6 QUANTITATIVE ANALYSIS. 

some distance in front of the supporting pillar of the balance. The 
instrument should be provided with screws for purposes of adjust- 
ment, a mechanical contrivance for supporting the beam above its 
bearing when not in use or during the removal or addition of 
weights, spirit-levels to enable the operator to give it a horizontal 
position, and be enclosed in a glass case to protect from dust. It 
should be placed in a room the atmosphere of which is not liable to 
be contaminated by acid fumes, in a situation free from vibration, 
and a vessel containing lumps of quicklime should be placed in the 
case to keep the enclosed air dry and prevent the formation of rust 
on any steel knife-edges or other parts. During weighing the doors 
of the balance should be shut, in order that currents of air may not 
unequally influence the pans. 

The Weights. — These should be preserved in a box having a sep- 
arate compartment for each. They must not be lifted directly with 
the fingers, but by a small pair of forceps. If grain-weights, they 
should range from 1000 grs. to ^ gr., a -^ weight being fashioned 
of gold wire to act as a "rider" on the divided beam, and thus in- 
dicate by its position lOOths and lOOOths of a grain. From -^ to 
10 grs. the weights may be of platinum : thence upward, to 1000 
grs., of brass. The relation of the weights to each other should be 
decimal. Metric decimal weights may range from 1000 grammes to 
1 gramme of brass, and thence downward to 1 centigramme of plat- 
inum, a gold centigramme rider being employed to indicate milli- 
grammes and tenths of a milligramme. 

Weights and Measures of "the U. S. Pharmacopoeia. — "The 
working formulae of the United States Pharmacopoeia are now so 
constructed that, in their practical application, any system of 
.weights or (in certain cases measures) may be used." " The 
weights and measures referred to by physicians in prescribing, 
and used by pharmacists in dispensing medicines, are, in the 
United States, either those of the ' apothecaries ' or troy system of 
weights and the wine measure, or those of the metric system." 

Troy Weights. — These are derived from the troy pound, and are 
exhibited in the following table, with their signs annexed : — 

One pound, ft) = 12 ounces = 5760 grains. 

One ounce, ^ = 8 drachms = 480 grains. 

One drachm, 3; = 3 scruples = 60 grains. 

One scruple, 9 = 20 grains. 

One grain, gr = 1 grain. 

It is highly important that persons engaged in preparing med- 
icines should be provided with troy weights. But those who are 
not so provided can make their avoirdupois weights available as 
substitute for troy weights by bearing in mind that 42.5 grains, 
added to the avoirdupois ounce, will make it equal to the troy 
ounce, and that 1240 grains, deducted from the avoirdupois pound, 
will reduce it to the troy pound. 

Measures. — These are derived from the wine gallon, and are given 
in the following table, with their signs annexed : — 



WEIGHTS AND MEASURES. 587 

One gallon, C = 8 pints = 61,440 minims. 

One pint, = 16 fluidounces = 7,680 minims. 

One nuidounce, f ^ = 8 fluidrachms = 480 minims. 

One nuidrachm, fg = 60 minims. 

One minim, rr\, = 1 minim. 



Relation of Troy Weight and Wine Measure. 

1 grain = 1.05 minims. 
1 3 = 63.2 " 
1 I = 505.6 " 



1 minim = 0.95 grains. 
If3 = 56.96 " 
1 f § =455.69 " 



The Metric System of weights (the word metric is from the 
Greek fxirpov, metron, measure) is greatly to be preferred to all 
others, the relation of the metric weights of all denominations to 
measures of length, capacity, and surface being so simple as to be 
within the perfect comprehension of a child ; while under the Brit- 
ish and American plans the weights have no such relation either 
with each other or with the various measures. Moreover, the metric 
system is in perfect harmony with the universal method of counting ; 
it is a decimal system. 

[It is perhaps impossible to realize, much more express, the ad- 
vantages we enjoy from the fact that in every country of the world 
the system of numeration is identical. That system is the decimal. 
Whatever language a man speaks, his method of numbering is deci- 
mal 5 his talk concerning number is decimal ; his written or printed 
signs signifying number are decimal. With the figures, 1, 2, 3, 4, 5, 
6, 7, 8, 9, he represents all possible variation in number, the posi- 
tion of a figure in reference to its companions alone determining its 
value, aiigure on the left hand of any other figure in an allocation 
of numeral symbols (for example, 1871) having ten times the value 
of that figure, while the figure on the right hand of any other has a 
tenth of the value of that other. When the youngest pupil is asked 
how many units there are in 1871, he smiles at the simplicity of the 
question, and says 1871. How many tens? 187, and 1 over. How 
many hundreds ? 18, and 71 over. How many thousands? 1, and 
871 over. But if he is asked how many scruples there are in 1871 
grains, how many drachms, how many ounces, he first inquires 
which drachms or which ounces are meant — avoirdupois ounces, 
troy ounces, or wine ounces — and then brings out his slate and 
pencil. And so with the pints or gallons in 1871 fluidounces, or 
the feet and yards in 1871 inches, or the pence, shillings, and 
pounds in 1871 farthings; to say nothing of cross questions, such 
as the value of 1871 articles at 2 dollars and 20 cents per dozen, or 
of the perplexity caused by the varying values of several individual 
weights or of measures of length, capacity, and surface in different 
parts of the country. What is desired is, that there should be an 
equally simple decimal relation among weights and measures and 
coins as already universally exists among numbers. This condition 
of things having already been introduced into most other countries, 
there is no good reason why it should not be accomplished in the 
United States and Great Britain.] 



588 



QUANTITATIVE ANALYSIS. 



The Metric System of weights and measures is founded on the 
metre. The engraving (Fig. 66) represents a pocket folding-meas- 

Fig. Q6. 



lU l\l\\\\\\\\\\U\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\]\\\\\\\\\\\\\\\\\\\\\\\\\\\}\\\\\\\\\\\\\\\\\\\T 

to. la Ta M. fcA 1c \7 |8 ~ r \i ! (in 



m 



The Decimetre. 

ure, the tenth part of a metre in length, divided into ten centimetres, 
and each centimetre into 10 millimetres. 

The units of the system with their multiples and submultiples 
are as follows : — 

Units. 

Length. — The Unit of Length is the Metre, derived from the 
measurement of the quadrant of a meridian of the earth. (Prac- 
tically, it is the length of certain carefully-preserved bars of metal 
from which copies have been taken.) 

Surface. — The Unity of Surface is the Are, which is the square 
of ten metres. 

Capacity. — The Unity of Capacity is the Litre, which is the cube 
of a tenth part of a metre. 

Weight. — The Unity of Weight is the Gramme, which is the weight 
of that quantity of distilled water, at its maximum density (4° C.), 
which fills a cube of the one-hundredth part of the metre. 

Table. 

Note. — Multiples are denoted by the Greek words " Deca," Ten, 

" Hecto," Hundred, "Kilo," Thousand. 
Subdivisions, by the Latin words " Deci," One-tenth, " Centi," 





One-hundredth, 


' Milli," One-thousandth. 


Quantities 




Length. 


Surface. Capacity. 


Weight. 


1000 




Kilo-metre 


. . . Kilo-litre 


Kilo-gramme. 


100 




Hecto-metre 


Hectare Hecto-litre 


Hecto-gramme. 


10 




Deca-metre 


. . . Deca-litre 


Deca-gramme. 


1 


(Units) 


METRE 


ARE LITRE 


GRAMME. 


.1 




Deci-metre 


. . . Deci-litre 


Deci-gramme. 


.01 




Centi-metre 


Centiare Centi-litre 


Centi-gramme. 


.001 




Milli-metre 


. . . Milli-litre 


Milli-gramme. 



When the Metric Method is exclusively adopted these units and this 
table, comprising the entire system of weights and measures, repre- 
sent all that will be essential to be learned in lieu of the numerous 
and complicated tables hitherto in use. Adopting the style of ele- 
mentary books on arithmetic, the Tables may be expanded in the 
following manner : — 



WEIGHTS AND MEASURES. 589 

10 Milligrammes make 1 Centigramme. 
10 Centigrammes " 1 Decigramme. 
10 Decigrammes " 1 Gramme. 
10 Grammes " 1 Decagramme. 

10 Decagrammes " 1 Hectogramme. 
10 Hectogrammes " 1 Kilogramme. 

10 Millilitres make 1 Centilitre, 

etc. 

10 Millimetres make 1 Centimetre, 
etc. 
Abbreviations. — Metre = m. ; decimetre = dm. ; centimetre == cm. ; 
millimetre — mm. ; kilometre =km. Square metre =??i 2 . ; cubric me- 
tre = m 3 . ; and so on. Litre —I. ; decilitre =dl. ; and so on. Kil- 
ogramme = kg.; dekagramme = dkg.; gramme =g. ; decigramme 
= dg. ; centigramme = eg. ; milligramme — mg. 

The following approximate equivalents of metrical units should 
be committed to memory : — 

1 Metre == 3 feet 3 inches and 3 eighths. 
1 Are = a square whose side is 11 yards. 

1 Litre = If pints. 
1 Gramme = 15J grains. 

The Kilometre is equal to 1100 yards. 

The Hectare = 1\ acres nearly. 

The Metric Ton of 1000 Kilogrammes = 19 cwt. 2 qrs. 20 lbs. 10 oz. 

The Kilogramme = 2 lbs. 3 J oz. nearly. 

For exact equivalents in many forms see pages 539 and 540. A 
litre of water at 39° F. weighs 15432 grains; at 50° F., 15429 
grains; at 60° F., it weighs 15418 grains; at 70° F., 15403 grains; 
and at 80° F., 15383 grains (Pile). (The word gramme is, in Eng- 
lish, frequently written gram, which too closely resembles the word 
grain.) 

Decimal Coinage. — In most countries where the metric system of 
weights and measures is employed a decimal division of coins is also 
adopted. This course, conjoined with the ordinary decimal method 
of enumerating, which, fortunately, is in universal use, renders cal- 
culations of all kinds most simple — easy to an extent which cannot 
be conceived in countries like England, where the operations of 
weighing, measuring, paying, and counting have only the most ab- 
surdly intricate relations to each other. 

The General Council under whose authority the British Pharma- 
copoeia is issued encourages medical practitioners and pharmacists 
in the adoption of the metric system, and gives the annexed state- 
ment of metric weights and measures : — 



590 QUANTITATIVE ANALYSIS. 

WEIGHTS AND MEASURES OF THE 
METRICAL SYSTEM. 

(From the British Pharmacopoeia of 1867.) 

Weights. 

1 Milligramme = the thousandth part of one grm., or 0.001 grm. 

1 Centigramme = the hundredth " 0.01 " 

1 Decigramme = the tenth " 0.1 " 

1 Gramme = weight of a cubic centimetre of 

water at 4° C. 1.0 " 

1 Decagramme = ten grammes 10.0 " 

1 Hectogramme = one hundred grammes 100.0 " 

1 Kilogramme = one thousand grammes 1000.0 (1 kilo.). 

Measures of Capacity. 

1 Millilitre = 1 cub. centim., or the meas. of 1 gram, of water. 
1 Centilitre == 10 " " 10 " " 

1 Decilitre = 100 " " 100 " " 

1 Litre =1000 " " 1000 " (lkilo.). 

Measures of Length. 

1 Millimetre = the thousandth part of one metre, or 0.001 metre. 
1 Centimetre = the hundredth 0.01 " 

1 Decimetre = the tenth 0.1 " 

1 Metre = the ten-millionth part of a quarter of the meridian 

of the earth. 

The National Convention for revising the Pharmacopoeia of the 
United States also recognizes the metric system of weights and 
measures by giving, in the last (sixth) edition of the Pharmacopoeia, 
Tables of the units of the metrical system with their multiples and 
submultiples, similar to the foregoing, and the following Tables 
showing the relation to each other of the metrical and troy systems. 
In some parts of the text of the work the metric system is that 
actually employed. 

TABLES OF WEIGHTS AND MEASURES. 

A.— MEASURES OF LENGTH. 

I. Relation of Metric to United States Measures of Length, 

1 Metre = 39.370432 inches. 

1 Decimetre = 3.937043' " 

1 Centimetre = 0.393704 " 

1 Millimetre = 0.039370 " 



WEIGHTS AND MEASURES. 



591 



II. Relation of United States to Metric Measures of Length. 

1 Yard (or 36 Inches) = 0.91439 Metre. 

1 Foot (or 12 Inches) = 30.40 Centimetres. 



nches. 




Centimetres. 


Inches. 




Centimetres. 


Inch. 




Centimetre. 


11 


= 


27.9 


5 


= 


12.7 


1 
2" 


= 


12.5 


10 


= 


25.4 


4 


— 


10.2 


1 


— 


6.25 


9 


= 


22.9 


3 


— 


7.6 


1 
8" 





3.12 


8 


= 


20.3 


2 


= 


5.1 


1 
TO" 


= 


1.54 


7 


= 


17.8 


1 


= 


2.5 


1 
"23 


= 


1.00 


6 


= 


15.2 















B.— MEASURES OF CAPACITY. 
III. Relation of Metric to United States Fluid Measures. 



Cubic Centim. Fluidounces. 


Cubic Centim. Fluidrachms. 


Cubic Centim. 


Minims. 


1,000 


— 


33.81 


15 


= 


4.06 


0.40 


= 


6.49 


950 


= 


32.12 


10 


= 


2.71 


0.35 


— 


5.68 


900 


= 


30.43 


9 


= 


2.43 


0.30 


== 


4.87 


850 


= 


28.74 


8 


= 


2.16 


0.25 


— 


4.06 


800 


= 


27.05 


7 


= 


1.89 


0.20 


= 


3.25 


750 


== 


25.36 


6 


= 


1.62 


0.19 


— 


3.08 


700 


== 


23.67 


5 


= 


1.35 


0.18 


— 


2.92 


650 


== 


21.98 


4 


= 


1.08 


0.17 


= 


2.76 


600 


= 


20.29 








0.16 


= 


2.60 


550 


= 


18.59 


Cubic Centim. 


Minims. 


0.15 





2.43 


500 


= 


16.90 


3 


— 


48.69 


0.14 


= 


2.27 


450 


= 


15.22 


2 


= 


32.46 


0.13 





2.11 


400 


" = 


13.53 


1 


— 


16.23 


0.12 


= 


1.95 


350 


= 


11.84 


0.95 


— 


15.42 


0.11 


= 


1.79 


300 


= 


10.14 


0.90 


— 


14.61 


0.10 


= 


1.62 


250 


= 


8.45 


0.85 


= 


13.80 


0.09 





1.46 


200 


= 


6.76 


0.80 


= 


12.98 


0.08 


= 


1.30 


150 


= 


5.07 


0.75 


= 


12.17 


0.07 


= 


1.14 


100 


= 


3.38 


0.70 


= 


11.36 


0.06 


= 


0.97 


30 


= 


1.01 


0.65 


= 


10.55 


0.05 


= 


0.81 








0.60 


= 


9.74 


0.04 


= 


0.65 


Cubic Centi 


m. Fluidrachms. 


0.55 


= 


8.93 


0.03 


= 


0.49 


25 


- 


6.76 


0.50 


= 


8.12 


0.02 


= 


0.32 


20 


= 


5.41 


0.45 


= 


7.30 


0.01 


= 


0.16 


IV. Relation of U 


nited St 


ATES 


to Metr 


ic Fluid 


Measures. 


Minims. 


Cubic Centim. 


Minims. 


Cubic Centim. 


Minims. 


Cubic Centim. 


1 


= 


0.06 


8 


= 


0.49 


15 


— 


0.92 


2 


= 


0.12 


9 


— 


0.55 


16 


= 


0.99 


3 


= 


0.18 


10 


= 


0.62 


17 


= 


1.05 


4 


= 


0.25 


11 


= 


0.6S 


IS 


=: 


1.11 


5 


= 


0.31 


12 


= 


0.74 


19 


= 


1.17 


6 


= 


0.37 


13 


r^: 


0.80 


20 


= 


1.23 


7 


= 


0.43 


14 


— 


0.86 


21 


= 


1.29 



592 



QUANTITATIVE ANALYSIS. 



Relation of 


United States 


to Metric Fluid Measures. — Cord. 


Mi Dims. 


Cubic Centim. 


Fluidrachms. Cubic Centim. 


Fluidounces. 


Cub. Centim. 


22 


— 


1.36 


3 


— 


11.09 


11 


— 


325.25 


23 


— 


1.42 


4 


— 


14.79 


12 


= 


354.82 


24 


==. 


1.48 


5 


= 


18.48 


13 


— 


384.40 


25 


— 


1.54 


6 


= 


22.18 


14 


= 


413.97 


26 


= 


1.60 


7 


— 


25.88 


15 


= 


443.54 


27 


= 


1.66 


8 


— 


29.57 


16 


= 


473.11 


28 


= 


1.73 


9 


— 


33.27 


17 


— 


502.69 


29 


= 


1.79 


10 


— 


36.97 


18 


= 


532.26 


30 


= 


1.85 


11 


— 


40.66 


19 


= 


561.93 


35 


= 


2.16 


12 


— 


44.36 


20 


— 


591.50 


40 


= 


2.46 


13 


== 


48.06 


21 


= 


'621.08 


45 


= 


2.77 


14 


■ — 


51.75 


22 


= 


650.65 


50 


— 


3.08 


15 


= 


55.45 


23 


= 


680.22 


55 


= 


3.39 


16 


— 


59.10 


24 


— 


709.80 


60 


= 


3.70 








25 


= 


739.37 


70 


= 


4.31 


Fluidounces. 




26 


= 


768.94 


80 


= 


4.93 


3 


= 


88.67 


27 


= 


798.51 


90 


= 


5.54 


4 


— 


118.24 


28 


== 


828.09 


100 


= 


6.16 


5 


= 


147.81 


29 


= 


857.66 


110 


= 


6.78 


6 


= 


177.39 


30 


=z 


887.23 


120 


' = 


7.39 


7 


— 


206.96 


31 


= 


916.80 








8 


= 


236.53 


32 


=z 


946.38 








9 


= 


266.10 


64 


== 


1892.75 








10 


= 


295.68 


128 


= 


3785.51 



C— WEIGHTS. 
V. Relation of Metric to Apothecaries' or Troy Weight. 



Grammes. 




Grains. 


Grammes. 




Grains. 


Grammes. 




Grains. 


0.0010 


— 


0.015 


0.0125 


— 


0.193 


0.120 


= 


1.852 


0.0013 


= 


0.019 


0.0150 


— 


0.231 


0.130 


— 


2.006 


0.0015 


— 


0.023 


0.0200 


— 


0.309 


0.140 


= 


2.161 


0.0020 


= 


0.031 


0.0250 


= 


0.386 


0.150 


= 


2.315 


0.0025 


= 


0.039 


0.0300 


= 


0.463 


0.160 


== 


2.469 


0.0030 


= 


0.046 


0.0350 


= 


0.540 


0.170 


= 


2.623 


0.0035 


= 


0.054 


0.0400 


== 


0.617 


0.180 


= 


2.778 


0.0040 


=± 


0.062 


0.0450 


= 


0.694 


0.190 


= 


2.932 


0.0045 


= 


0.069 


0.050 


= 


0.772 


0.200 


= 


3.086 


0.0050 


— 


0.077 


0.055 


= 


0.849 


0.210 


= 


3.241 


0.0055 


— 


0.085 


0.060 


— • 


0.926 


0.220 


= 


3.395 


0.0060 


= 


0.093 


0.065 


= 


1.003 


0.230 


= 


3.549 


0.0065 


= 


0.100 


0.070 


= 


1.080 


0.240 


= 


3.704 


0.0070 


— 


0.108 


0.075 


= 


1.157 


0.250 


= 


3.858 


0.0075 


— 


0.116 


0.080 


= 


1.235 


0.260 


=z 


4.012 


0.0080 


= 


0.123 


0.085 


= 


1.312 


0.270 


= 


4.167 


0.0085 


= 


0.131 


0.090 


— 


1.389 


0.280 


— : 


4.321 


0.0090 


== 


0.139 


0.095 


= 


1.466 


0.290 


= 


4.475 


0.0095 


= 


0.147 


0.100 


= 


1.543 


0.300 


= 


4.630 


0.0100 


= 


0.154 


0.110 


= 


1.698 


0.310 


= 


4.784 



WEIGHTS AND MEASURES. 



593 



Relation or 


Metric 


to Apothecaries' or 


Troy Weig 


iit. — Cont. 


Grammes. 


Grains. 


Grammes. 


Grains. 


Grammes. 


Grains. 


0.320 = 


4.938 


13 


= 


200.621 


39 


— 


601.862 


0.330 = 


5.093 


14 


= 


216.053 


40 


= 


617.294 


0.340 = 


5.247 


15 


— : 


231.485 


50 


= 


771.617 


0.350 = 


5.401 


16 


= 


246.918 


60 


— 


925.941 


0.360 = 


5.556 


17 


— 


262.350 


70 


= 


1080.264 


0.370 = 


5.710 


18 


= 


277.782 


80 


= 


1234.588 


0.380 = 


5.864 


19 


=■ 


293.215 


90 


= 


1388.911 


0.390 = 


6.019 


20 


— 


308.647 


100 


— 


1543.235 


0.400 = 


6.173 


21 


= 


324.079 


125 


= 


1929.044 


0.500 = 


7.716 


22 


= 


339.512 


150 


E 


2314.852 


0.600 = 


9.259 


23 


— 


354.944 


200 


— 


3086.470 


0.700 = 


10.803 


24 


= 


370.376 


250 


= 


3858.087 


0.800 = 


12.346 


25 


— 


385.809 


300 


= 


4629.705 


0.900 = 


13.889 


26 


— 


401.241 


333 


— 


5144.118 


1 = 


15.432 


27 


= 


416.673 


350 


= 


5401.322 


2 = 


30.865 


28 


— 


432.106 


400 


— 


6172.940 


3 = 


46.297 


29 


= 


447.538 


450 


= 


6944.557 


4 = 


61.729 


30 


= 


462.970 


500 


= 


7716.174 


5 = 


77.162 


31 


= 


478.403 


600 


= 


9259.409 


6 = 


92.594 


32 


= 


493.835 


700 


= 


10802.644 


7 = 


108.026 


33 


= 


509.268 


750 


= 


11574.262 


8 = 


123.459 


34 


= 


524.700 


800 


= 


12345.879 


9 = 


138.891 


35 


= 


540.132 


900 


— 


13889.114 


10 = 


154.323 


36 


= 


555.565 


1000 


= 


15432.350 


11 = 


169.756 


37 


= 


570.997 








12 = 


185.188 


38 


= 


586.429 








VI. The Relation op 


Apothecaries' (or Tro 


y) to Metric Weight. 


Grains. 


Grammes. 


Grains. 




Grammes. 


Grains. 




Grammes. 


A = 


0.00101 


l 


= 


0.01620 


14 


= 


0.90718 


1 — 
TJTJ 


0.00108 


l 


= 


0.02160 


15 


— 


0.97198 


1 

7J7J 


0.00130 


1 
2 


= 


0.03240 


16 


= 


1.037 


A = 


0.00135 


3 

3" 


== 


0.04860 


17 


= 


1.102 


i — 


0.00162 


1 


= 


0.06480 


18 


= 


1.166 


l — 
"3"(T — 


0.00180 


1* 


= 


0.09720 


19 


= 


1.231 


1 — 

¥3" — 


0.00202 


2 


= 


0.12960 


20 


= 


1.296 


* = 


0.00216 


2£ 


= 


0.16200 


21 


= 


1.36] 


A = 


0.00259 


3 


= 


0.19440 


22 


=r 


1.426 


i — 


0.00270 


4 


= 


0.25920 


23 


= 


1.458 


1 — 


0.00324 


5 


zn_- 


0.32399 


24 


= 


1.555 


A = 


0.00360 


6 


= 


0.38879 


25 


= 


1.620 


1 = 


0.00405 


7 


= 


0.45359 


26 


= 


1 .685 


1 = 

A 
A 
* = 

77 


0.00432 


8- 


= 


0.51839 


27 


= 


1.749 


0.00540 


9 


= 


0.58319 


28 


= 


1.814 


0.00648 


10 


= 


0.64799 


29 


= 


1 .869 


0.00810 


11 


= 


0.71297 


30 


= 


1.944 


0.0I0S0 


12 


= 


0.77759 


40 


= 


2.592 


0.01296 


13 


= 


0.84239 


50 


= 


3.240 



594 



QUANTITATIVE ANALYSIS. 



Relation of Apothecaries' (or Troy) to Metric Weight. — Cord. 



Drachn 


s. 


Grammes. 


Ounces. 




Grammes. 


Ounces. 




Grammes. 


{ 


— 


3.888 


1* 


— 


46.655 


11 


— 


342.138 


2 


= 


7.776 


2 


= 


62.207 


12 


= 


373.250 


3 


= 


11.664 


3 


— 


93.310 


13 


= 


404.345 


4 


— 


15.552 


4 


= 


124.414 


14 


= 


435.449 


5 


— 


19.440 


5 


— 


155.517 


15 


— 


466.552 


6 


= 


23.328 


6 


= 


186.621 


16 


= 


497.656 


7 


= 


27.216 


7 


= 


217.724 


17 


= 


528.759 








8 


= 


248.823 


18 


= 


559.863 


Ounces. 






9 


= 


279.931 


19 


— 


590.966 


1 


= 


31.103 


10 


= 


311.035 


20 


= 


622.070 




VII. 


Relation 


of Met 


RIC 


to Avoirdupois 


Weight. 




Avoirdupois Ounces 


Avoirdupois Ounces 




Avoirdupois Ounces 




and Grains. 




and Grains. 




and Grains. 


Grammes. 


Oz. Grs. 


Grammes. 




Oz. Grs. 


Grammes. 


Oz. Grs. 


28.35 : 




50 


— 


1 334 


500 


— 


17 279 


29 


= 


1 10 


60 


= 


2 50J 


550 


= 


19 175 


30 


= 


1 25J 


70 


= 


2 205 


600 


— 


21 72 


31 


= 


1 41 


• 80 


= 


2 359 


650 


= 


22 4051 


32 


= 


1 561 


90 


= 


3 761 


700 


= 


24 303 


33 


— 


1 72 


100 


= 


3 2301 


750 


= 


26 1981 


34 


= 


1 871 


150 


= 


5 127 


800 


= 


28 96 


35 


= 


1 103 


200 


= 


7 24 


850 


= 


29 429 


36 


==z 


1 118 


250 


= 


8 358 


900 


= 


31 326* 


37 


= 


1 1331 


300 


= 


10 255 


950 


= 


33 222 


38 


= 


1 149 


350 


= 


12 1511 


1000 


= 


35 120 


39 


= 


1 164* 


400 


= 


14 48 








40 


= 


1 180 


450 


= 


15 382 










VIII. 


Relatio> 


r of Avoirdupois to I 


Ietric 


Weight. 


Avoirdupois 
Ounces. 


Grammes. 


Avoirdupo 
Ounces. 


is 


Grammes. 


Avoirdi 
Poun 


poia 

Is. 


Grammes. 


tV 


= 


1.772 


7 


= 


198.447 


1 


= 


453.592 


* 


= 


3.544 


8 


= 


226.796 


2 


= 


907.18 


l 

4 


— 


7.088 


9 


= 


255.146 


3 


— 


1360.78 


i 


= 


14.175 


10 


= 


283.496 


4. 


= 


1814.37 


1 


= 


28.350 


11 


= 


311.846 


5 


= 


2267.96 


2 


= 


56.699 


12 


= 


340.195 


6 


= 


2721.55 


3 


= 


85.049 


13 


— 


368.544 


7 


= 


3175.14 


4 


= 


113.398 


14 


= 


396.894 


8 


— 


3628.74 


5 


= 


141.748 


15 


= 


425.243 


9 


= 


4082.33 


6 


= 


170.098 








10 


== 


4535.92 



The following Tables, from the British Pharmacopoeia and the 
Diary of Messrs. De La Rue, will be found useful for reference : — 



WEIGHTS AND MEASURES. 



595 



WEIGHTS AND MEASURES OF THE 
BRITISH PHARMACOPCEIA OF 1867. 



1 Grain 
1 Ounce 
1 Pound 



Weights. 



oz. = 

lb. = 16 ounces - 



437.5 grains. 
7000 " 



1 Minim 
1 Fluidrachm 
1 Fluidounce 
1 Pint 
1 Gallon 



Measures of Capacity. 

min. 

fl. dr. = 

fl. oz. = 

0. = 

C. = 



60 minims. 

8 nuidrachms. 
20 fluidounces. 

8 pints. 



1 line = 
1 inch - 



Measures of Length. 
= 7 9 inch. 



: 39^1393 seconds-pendulum. 

12 " = 1 foot. 

36 " =3 feet = 1 yard. 

Length of pendulum vibrating seconds of mean] 

time in the latitude of London in a vacuum at I 39.1393 inches, 
the level of the sea ) 

(1 cubic inch of distilled water at 62° F. and 30 inches barom. = 
252.458 grains.) 

Relation of British Measures to Weights. 



1 Minim is the measure of 

1 Fluidrachm " 

1 Fluidounce " 1 ounce or 

1 Pint " 1.25 pounds or 

1 Gallon " 10 pounds or 



0.91 grain of water. 
54.68 grains of water. 
437.5 " 

8750.0 " 

70,000.0 " 



(Gtt. == guttce, drops. The term " drop " indicates a quantity which 
is indefinite, and should only be used when approximativeness is 
alone desired.) 

Relation of Wine Measures to Cubic Measure. 

One Gallon = 231. Cubic Inches. 

One Pint = 28.875 Cubic Inches. 

One Fluidounce = L.80468 Cubic [nches. 
One Fluidrachm = 0.22558 Cubic Ench. 
One Minim = 0.00375 Cubic Inch. 



596 



QUANTITATIVE ANALYSIS. 



2 








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598 QUANTITATIVE ANALYSIS. 

QUESTIONS AND EXERCISES. 

960. Mention some advantages of a decimal system of weights and 
measures. 

961. What is the name of the chief unit of the metric decimal 
system of weights and measures ? 

962. Mention the names of the metric units of surface, capacity, 
and weight, and state how they are derived from the unit of length. 

963. How are multiples of metric units indicated? 

964. State the designations of submultiples of metric units. 

965. How many metres are there in a kilometre ? 

966. How many millimetres in a metre ? 

967. How many grammes in 5 kilogrammes ? 

968. How many milligrammes in 13 j grammes? 

969. In 1869 centigrammes how man}' grammes ? 

970. In a metre measure 5 centimetres wide and 1 centimetre 
thick, how many cubic centimetres? 

971. How many litres are contained in a cubic metre of any 
liquid ? 

972. State the British equivalent of the metre. 

973. How many square yards in an are? 

974. How many fluidounces in a litre? 

975. How many ounces in a kilogramme? 

976. Give the relation of a metric ton (1000 kilos.) to a British 
ton. 

977. How many grains are there in 1 ton ? 

978. How many ounces in 1 ton ? 

979. How many grains of water in 1 nuidrachni? 

980. How many minims in 1 pint ? 

981. How many grains in 1 pint of water? 

982. Whence is the British unit of length derived ? 



Specific Weight or Specific Gravity. 

The specific weight of a substance is its weight in comparison with 
weights of similar bulks of other substances. This comparative 
heaviness of solids and liquids is conventionally expressed in rela- 
tion to water : they are considered as being lighter or heavier than 
water. Thus, water being regarded as unity = 1, the relative weight, 
or specific weight, of ether is represented by the figures .720 (it is 
nearly three-fourths, .750, the weight of water), oil of vitriol by 
1.843 (it is nearly twice, 2.000, as heavy as water). The specific 
weight of substances is. moreover, by generally accepted agreement, 
the weight of similar volumes at 15° C. (59° F.), except in the case 
of alcohol and wine, which are at present taken at 15.6° C. (60° F.), 
to maintain consistency with United States laws and regulations; 
for the weight of a definite volume of any substance will vary 
according to temperature, becoming heavier when cooled and lighter 
when heated, different bodies (gases excepted) differing in their rate 
of contraction and expansion. While, then, specific weight — or, 



SPECIFIC GRAVITY. 599 

conventionally, specific gravity — is truly the comparative weight of 
equal bulks, the numbers which in America commonly represent 
specific gravities are the comparative weights of equal bulks at 
15° C. (59° F.), water being taken as unity.* The standard of com- 
parison for gases was formerly air, but is now usually hydrogen. 

Specific Gravity of Liquids. 

Procure any small bottle holding from 100 to 1000 grains 
(fig. 67) and having a narrow neck ; counterpoise it in a deli- 
cate balance ; fill it to about halfway up the neck with pure 
distilled water having a temperature of 15° C. ; ascertain the 
weight of the water, and, for convenience, add or subtract a 
drop or two, so that the weight shall be a round number of 
grains ; mark the neck by a diamond or file-point at the part 
cut by the lower edge of the curved surface of the water. 
Consecutively fill up the bottle to the neck-mark with several 
other liquids, cooled or warmed to 15° C, first rinsing out the 
bottle once or twice with a small quantity of each liquid, and 
note the weights ; the respective figures will represent the 
relative weights of equal bulks of the liquids. If the capacity 
of the bottle is 10, 100, or 1000 grains, the resulting weights 
will, without calculation, show the specific gravities of the 

Fig. 67. Fig. 68. Fig. 69. Fig. 70. 



Specific-Gravity Bottles. 

liquids ; if any other number, a rule-of-three sum must be 
worked out to ascertain the weight of the liquids as compared 
with 1 (or 1.000) of water. Bottles conveniently adjusted to 

* The true weight of the body is its weight in air plus the weight 
of an equal bulk of air, and minus the weight of a bulk of air equal 
to the bulk of brass or other weights employed ; or, in other words, 
its weight in vacuo uninfluenced by the buoyancy of the air; but such 
a correction of the weight of a body is seldom necessary, or, indeed, 
desirable. Density is sometimes improperly regarded as synonymous 
with specific gravity. It is true that the density of a body is in exact 
proportion to its specific gravity, but the former is more correctly the 
comparative bulk of equal weights, while specific gravity is the com- 
parative weight of equal bulks. 



600 



QUANTITATIVE ANALYSIS. 



contain 250, 500, or 1000 grains, or 100 or 50 grammes, of 
water when filled to the top of their perforated stopper (Fig. 
09), and other forms of the instrument (Figs. 68 and 70), are 
sold by all chemical-apparatus makers. Figure 70 is that of a 
bottle extremely useful in ascertaining the specific gravities of 
very volatile liquids. 

Verify some of the following stated specific gravities of substances 
official in the U. S. Pharmacopoeia, 1880: — 



Acid, Acetic 1.048 

" " dil 1.0083 

" " Glacial... 1.056-1 .058 

" Hydrobromic dil 1.077 

" Hydrochloric 1.160 

" " dil 1.049 

" Lactic 1.212 

" Nitric 1.420 

" " dil 1.059 

" Oleic 800-.810 

" Phosphoric 1.347 

" " dil 1.057 

" Sulphuric 1.840 

" " Aromat 955 

" " dil 1.067 

" Sulphurous 1.022-1.023 

either 750 

" Acetic 889-.897 

" Fortior 725 

Alcohol 820 

" dil 928 

Amyl Nitris 872-.874 

Aq. Amnion 959 

" " Fort 900 

Bals.Peru 1.135-1.150 

Benzinum 670-.675 

Bromum 2.990 

Camphora 990-.995 

Carbonei Bisulphidum 1.272 

Cera Alba 0.965-0.975 

CeraFlava 955-.967 

Cetaceum 0.945 

Chloroform Purif. 1.485-1.490 

" Venali 1.470 

Copaiba 940-.993 

Creosote 1.035-1.085 

FelBovis 1.018-1.028 

Glycerinum 1.250 

Hydrargyrum 13.5 

Iodoformum 2.00 

Liq. Ammon. Acet 1.022 



Liq.Calcis 1.0015 

" Ferri Acetatis 1.160 

" " Chloridi 1.405 

•' " Citratis 1.260 

" " Nitratis 1.050 

" " Subsulph 1.555 

" " Tersulph 1.320 

" Hydrarjr. Nit 2.100 

" PlunibfSubacetatis... 1.228 

" Potassee 1.036 

" Potassii Citratis 1.059 

" Sodse 1.059 

" " Chloratse 1.044 

" SodiiSilicatis... 1.300-1.400 

". ZinciChlor 1.555 

Mel 1.101-1.105 

Oleum Adipis 0.900-0.920 

iEthereum 0.910 

, -, . [1.060-1.070 

Amygd.Amar.| L043 _ 1>049 

" Express... .914-.920 

Anisi 976-.990 

AurantiiCort 860 

" Flor... .850-.890 

Bergamii 860-.890 

Cajuputi 920 

Cari 920 

Caryoph 1.050 

Chenapodii 920 

Cinnamomi {Ceylon) 1.040 
" {Chinese) 1.060 

Copaiba.. 890 

Coriandri 870 

Cubebse.. ; 920 

Erigerontis 850 

Eucalypti 900 

Foeniculi 960 

GaultheriEe 1.180 

Gossypii Sem... .920-.930 

Hedeomse 940 

Juniperi 870 



SPECIFIC GRAVITY. 



601 



Oleu 



m Lavendulse 

Flor 

Limonis 

Lini 

Menth. Pip 

Virid 

Morrhuae 920- 

Myrcias 1 

Myristicae 

Ol'ivse 915 

Picis Liquida 

Pimentae 1 

Ricini 950- 



Rosmarini 

Rutae 

Sabinae 

Santali 

Sassafras 1 

Sesami 914— 

Sinapis Yol 1.017—1 



.890 
.890 
.850 
.936 
.900 
.900 
,925 
,040 
.930 
.918 
.970 
040 
,970 
.860 
.900 
.880 
.910 
.945 
.090 
.923 
.021 



Oleum Succini 920 

" Tcrebinthinae 855-870 

" Thymi .880 

" Tiglii 940-.955 

" Valerianae 950 

Petrolatum 835-.860 

Phosphorus (at 50° F.) 1.83 

Resina 1.070-1.080 

Sp. iEtheris Nitrosi... .823-.825 

u Ammoniae 810 

" Ammoniae Aromat 885 

" Frumenti 930-.917 

" ViniGallici 941-.925 

Syrupus 1.310 

Syr. Acidi Hydriodici 1.300 

Thymol 1.028 

Tinct. Ferri Acetatis 0.950 

" " Chloridi 0.980 

Yinum Album 990-1.010 

" Rubrum 989-1.010 

Zincum 6.9 



Hydrometers. -^-The specific gravity of liquids may be ascertained 
without scales and weights by means of a hydrometer, an instru- 
ment usually of glass, having a graduated stem and a bulb or bulbs 
at the lower part. The specific gravity of a liquid is indicated by 
the depth to which the hydrometer sinks in the liquid, the zero of 
the scale marking the depth to which it sinks in pure water. Hydrom- 
eters constructed for special purposes are known under the names 
of saccharometer, galactometer, elaeometer, urinometer, alcohol- 
ometer. Hydrometers require a considerable quantity of liquid to 
fairly float them, and specific gravities observed with them are less 
delicate and trustworthy than those obtained by the balance ; never- 
theless, they are exceedingly useful for many practical purposes where 
the employment of a delicate balance would be inadmissible. 



Specific Gravity of Solids in Mass. 

Weigh a piece (50 to 250 grains) of any solid substance 
heavier than water in the usual manner. Then weigh it in 
water by suspending it from a shortened balance-pan by a tine 
thread or hair and immersing in a vessel of water (Fig. 71). 
The buoyant properties of the water will cause the solid ap- 
parently to lose weight; this loss in weight is the exact weight 
of an equal hulk of loafer. The weight of the substance and 
the weight of an equal bulk of water being thus ascertained. 
a rule-of-three sum shows the proportional weight of the sub- 
stance to 1.000 of water. To express the same tiling by rule, 
divide the weight in air by the loss of weight in water; the 



602 



QUANTITATIVE ANALYSIS. 



resulting number is the specific gravity in relation to 1 part of 
water, the conventional standard of comparison. 

Fig. 71. 




Weighing a Solid in Water. 

Verify some of the following specific gravities : — 



Aluminium 2.56 

Antimony 6.71 



Bismuth., 

Coins, English, gold 

" silver... 
" " bronze . 

Copper 

Gold 

Iron 



9.83 
17.69 
10.30 

8.70 

8.95 
19.34 

7.84 



Lead 11.36 

Magnesium 1.74 

Marble 2.70 

Phosphorus 1.77 

Platinum 21.53 

Silver 10.53 

Sulphur 2.05 

Tin 7.29 

Zinc 7.14 



. . Specific gravities of solid substances should be taken in water 
having a temperature of about 15° C. (59° F.). The body should be 
immersed about half an inch below the surface of the water ; adher- 
ing air-bubbles must be carefully removed ; the body must be quite 
insoluble in water. 

It is assumed that the student is able to work equally well with 
grain or gramme weights. 

Specific Gravity of Solids in Powder or Small 
Fragments. 

Weigh the particles ; place them in a counterpoised specific- 
gravity bottle of known capacity, and fill up with water, taking 
care that the substance is thoroughly wetted ; again weigh. 
From the combined weights of water and substance subtract 
the amount due to the substance ; the residue is the weight of 



SPECIFIC GRAVITY. 603 

the water. Subtract this weight of water from the quantity 
which the bottle normally contains ; the residue is the amount 
of water displaced by the substance. Having thus obtained 
the weights of equal bulks of water and substance, a rule-of- 
three sum shows the relation of the weight of the substance to 
1 part of water — the specific gravity. 

Or suspend a cup, short glass tube, or bucket from a short- 
ened balance-pan ; immerse in water ; counterpoise ; place the 
weighed powder in the cup, and proceed as directed for taking 
the specific gravity of a solid in mass. 

This operation may be conducted on fragments of any of the sub- 
stances the specific gravities of which are given in the foregoing 
Table, or on a powdered piece of marble the specific gravity of 
which has been taken in mass. The specific gravity of one piece of 
glass, first in mass, then in powder, may be ascertained ; the result 
should be identical. The specific gravity of shot is about 11.350; 
sand, 2.600 ; mercury, 13.56. 

Specific Gravity of Solids Soluble in Water. 

Weigh a piece of sugar or other substance soluble in water ; 
suspend it from a balance in the usual manner, and weigh it in 
turpentine, benzol, or petroleum, the specific gravity of which 
is known or has been previously determined ; the loss in weight 
is the weight of an equal bulk of the turpentine. Ascertain 
the weight of an equal bulk of water by calculation : — 

Sp. gr. of , sp. gr. of , . observed m equal bulk 
turpentine ' water bulk of turp. ' of water. 

The exact weights of equal bulks of sugar and water being 
obtained, the weight of a bulk of sugar corresponding to 1.000 
of water is shown by a rule-of-three sum ; in other words, 
divide the weight of sugar by that of the equal bulk of water ; 
the quotient is the' specific gravity of sugar. The stated specific 
gravity of the sugar ranges from 1.590 to 1.007. 

Specific Gravity of Solids Lighter than Water. 

This is obtained in a manner similar to that for solids 
heavier than water ; but the light body is sunk by help of a 
piece of heavy metal, the bulk of water which the latter dis- 
places being deducted from the bulk displaced by both ; the 
remainder is the weight of a bulk of water equal to the bulk 
of the light body. For instance, a piece of wood weighing 1^ 
grammes (or grains) is tied to a piece of metal weighing 22 
grammes, the loss of weight of the metal in water having been 



604 QUANTITATIVE ANALYSIS. 

previously found to be 3 grammes. The two, weighing 34 
grammes, are now immersed, and the loss in weight found to 
be 26 grammes. But of this loss 3 grammes have been proved 
to be due to the buoyant action of the water on the lead ; the 
remaining 23 therefore represent the same effect on the wood ; 
23 and 12 therefore represent the weights of equal bulks of 
water and wood. As 23 are to 12, so is 1 to .5217. Or, 
shortly, as before, divide the weight in air by the weight of an 
equal bulk of water ; .5217 is the specific gravity of the wood. 
Another specimen of wood may be found to be three-fourths 
(.750) the weight of water, and others heavier. Cork varies 
from .100 to .300. 

The specific gravity of a very minute quantity of a heavy or light 
substance may be ascertained by noting the specific gravity of a fluid 
in which it, being insoluble, neither sinks nor swims, or by immers- 
ing it in a weighed piece of paraffin whose specific gravity is known, 
noting the specific gravity of the whole, and deducting the influence 
of the parafnn. 

Specific Gravity of Gases. 

This operation is similar to that for liquids. A globe exhausted 
of air and holding from 1 to 4 litres (or quarts) is suspended from 
the arm of a balance, and counterpoised by a similar flask. Gases 
are introduced in succession and their weights noted. A rule-of- 
three sum shows their specific gravity in relation to air or hydrogen, 
whichever be taken as a standard. 

Correction of the Volume of Gases for Pressure. — The height of 
the barometer at the time of manipulation is noted. Remembering 
the fact that " the bulk of a gas is inversely as the pressure to which 
it is subjected" (Boyle and Mariotte), a simple calculation shows 
the volume which the gas would occupy at 760 millimetres (or 
29.922 inches), the standard pressure (30 inches is sometimes adopted 
as the standard in England*). Thus, 40 volumes of a gas at 740 milli- 
metres pressure are reduced to 39 when the pressure becomes 760 mil- 
limetres (or 90 vols, at 29 ins. barom. become 87 vols, at 30 inches). 

Correction of the Volume of Gases j'or Temperature. — This is don^ 
in order to ascertain Avhat volume the gas would occupv at 0° C. (32° 
F.), or 15° C. (59° F.), or 15°.5 C. (60 o< F.), according to the standard 
taken. Gases are equally affected by equal variations in tempera- 

* In France the conventional standard height of the barometer is 
760 millimetres at 0° C. (32° F.) ; in England it is 30 indies, the 
temperature of the mercurial column being 60° F. 760 millims. is 
equivalent to 29.922 inches, but the expansion of the metal between 
32° F. and 60° F. increases the length of the column to 30.005 inches. 
The standards are therefore almost identical, difference in true length 
being counterbalanced by the temperature at which the length is ob- 
served. 



SPECIFIC GRAVITY. 605 

ture (Charles). They expand about 0.3665* per cent. (^3) of their 
volume at the freezing point of water for every C. degree (0.2036), or 
¥ ^ T for every F. degree (Regnault). Thus, 8 volumes of gas at 3 
C. will become 8.293 at 10° C. ; for if 100 become 103.665 on being 
increased in temperature 10° C, 8 will become 8.293 (or if 100 be- 
come 102.036 on being increased 10° F., 8 will become 8.1629). 

Vapor-Density. — Vapors are those gases which condense to liquids 
at common temperatures. By the density of a vapor is meant its 
specific gravity. The density of a vapor is the ratio of any given 
volume to a similar volume of air or hydrogen at the same tempera- 
ture and pressure. But for convenience of comparison this experi- 
mental specific gravity is referred, by calculation as just described 
for permanent gases, to a temperature of 0° C. and 760 millimetres 
barom. A teaspoonful or so of liquid is placed in a weighed flask 
of about the capacity of a common tumbler and having a capillary 
neck 5 the flask is heated in an oil-bath to a temperature considerably 
above the boiling-point of the liquid ; at the moment vapor ceases 
to escape the neck is sealed by a blowpipe-flame and the tempera- 
ture of the bath noted 5 the flask is then removed, cooled, cleaned, 
and weighed ; the height of the barometer is also taken. The neck 
of the flask is next broken off beneath the surface of water or mer- 
cury (which rushes in and fills it), and again weighed, by which its 
capacity in cub. centims. is found. From these data the volume of 
vapor yielded by a given weight of liquid is ascertained by a few 
obvious calculations. The capacity of the globe having been ascer- 
tained, the weight of an equal bulk of airf is obtained by a rule-of- 
three sum. This weight of air is deducted from the original weight 
of the flask, which gives the true weight of the glass. The weight 
of the glass is next subtracted from the weight of the flask and con- 
tained vapor (now condensed), which gives the weight of material 
used in the experiment. The volume which this weight of material 
occupied at the time of experiment is next corrected for temperature 
(to 0° C.) and pressure (760 millimetres) in the manner just described. 
The weight of a similar volume of hydrogen is next found.J The 
weights of equal volumes of hydrogen and vapor being thus deter- 
mined, the amount of vapor corresponding to one of hydrogen (the 

* Correeted for the difference between the mercurial and air thermo- 
meters, the coefficient of expansion of air is 0.003656 (Miller). The 
coefficient of expansion of different gases varies very slightly, being 
somewhat higher for the more liquefiable gases. 

f 1 cub. centim. of air at 0° C. and 760 millims. weighs 0.001203 
gramme. 

% 1 litre (1000 cub. centims.) of hydrogen at 0° C. and 760 milli- 
metres (the barometer being at 0° C.) weighs 0.0896 gramme — a quan- 
tity sometimes termed a crith (from icpidq, krithe, a barley-corn — figu- 
ratively, a small weight); thus a litre of oxygen weighs 16 criths, 
chlorine 35.5 criths, etc. 100 cubic inches of hydrogen at 32° F. weigh 
2.265 grains; at 60° F., 2.143 grains (the barometer being 30 ins. at 
60° F. in both cases). 100 cubic inches of air at 32° F. weigfc 32.698 
grains; at 60° K., 30.035 (barom. 30 ins. at 60° F.). 1 cubic inch of 
water weighs 252.5 (25.2.458 at 62° F. and 30 ins. bar.) grains. 1 gallon 
of water contains 277] (277.27 1 at 62° V.) cubic inches, 



606 QUANTITATIVE ANALYSIS. 

specific gravity or vapor-density) is shown by a short calculation. 
This process of finding the weight of a given volume of vapor is by 
Dumas. Gay-Lussaos consists in determining the volume of a given 
weight ; it has been improved by Hofmann. An excellent method 
by V. and C. Meyer consists, like that of Gay-Lussac. in determin- 
ing the volume of the vapor of a given weight of a fluid or solid, but 
differs in the volume of the vapor being ascertained from an equal 
volume of air which the vapor is made to displace. (For a detailed 
description of this method ar.d a drawing of the apparatus see any 
of the larger manuals of physics.) 

Experiment shows that the specific gravities of many gases and 
vapors on the hydrogen scale, and the proportions in which they 
combine by weight, are identical. Thus, chlorine is 35.5 times as 
heavy as hydrogen, and 35.5 parts unite with 1 of hydrogen to form 
hydrochloric acid gas. Hence, if the specific gravity of a gas or 
vapor is known, its combining proportion may be predicated with 
reasonable certainty, and vice versa. In applying this rule to gas- 
eous or vaporous compounds attention must be paid to the extent to 
which their constituent gases contract at the moment of combination 
or expand at the moment of decomposition. Thus, steam is found to 
be composed of two volumes of hydrogen and one of oxygen, the 
three volumes of constituents condensing to two at the moment of 
combination. Hence, steam may be expected to be nine times as 
heavy as hydrogen ; which experiment confirms. 

These relations may be so expressed as to include both element- 
ary and compound gases and vapors ; thus, molecular iceights and 
specific iceights are identical. Molecular weights represent two vol- 
umes of a gas ; specific gravity conventionally represents the relative 
weight of a gas compared with 1 volume of hydrogen or air : hence 
the specific gravity of a gas or vapor on the H scale is found by cal- 
culation on simply dividing the molecular weight by 2 : on the air- 
scale, by dividing the hydrogen numbers by 14.44. For example, 

Specific Gravit}'. 



Name. 


Molecular 
formula. 


Molecular 
weight. 


H = 2. 


H = l. 


Air=l. 


Hydrogen . . . 


. H 2 


2 


2 


1 


.069 


Chlorine . . . 


. CL 


71 


71 


35.5 


2.460 


Oxygen . . . 


. 0, 


32 


32 


16 


1.108 


Nitrogen . . . 


. n; 


28 


28 


14 


.970 


Steam .... 


. H 2 


18 


18 


9 


.625 


Ammonia gas 


• NH 3 


17 


17 


8.5 


.589 


Carbonic acid gas 


. C0 2 


44 


44 


22 


1.524 


Alcohol (vapor) 


. C 2 H 6 


46 


46 


23 


1.593 


Air 






28.88 


14.44 


1.000 



These specific gravities closely correspond with those obtained by 
actual experiment. The specific gravity of any gas or vapor may 
therefore be calculated if the following data are at hand : (a) form- 
ula, (b) atomic weight of constituent elements ; these give the mo- 
lecular weight, and the molecular weight divided by 2 is the specific 
gravity on the hydrogen-scale. Specific gravity on the air-scale is 
then deducible, if {<) the specific gravity of "air (14.44) in relation 



SPECIFIC GRAVITY. 607 

to Irydrogen be remembered. The absolute weight of any volume 
of a gas or vapor on the metric system is then obtainable if (d) the 
weight of a litre of hydrogen (0.0896 gramme) be known, or on the 
English plan by remembering (e) that 100 cubic inches of hydrogen 
at 60° F. weigh 2.143 grains (100 cubic inches of air at 60° F. weigh 
30.935 grains). 

In confirmation of these statements regarding the mutual relation of 
specific gravity and atomic weight a remarkable fact may be mentioned. 
Regnault several years ago found the weights of I litre of hydrogen and 
oxygen to be respectively .089578 and 1 .429802 grammes. The latter 
number divided by the former gives 15.96 as the specific gravity of 
oxygen. Stas, in recent experimental researches on combining pro- 
portions, finds the atomic weight of oxygen to be not 16, but 15.96. 
' Exceptions to the law occur in a few compounds and in arsen- 
icum and phosphorus, whose vapor-densities are twice that indicated 
by the rule. Possibly, in these cases the temperature employed is 
insufficient to dissociate an unusually complex molecule into mole- 
cules of usual complexity. As regards compounds, and, possibly, 
as regards those elements in which the observed density is only half 
that indicated by the rule, heat may, and in some cases probably 
does, produce molecular dissociation (thermolysis) into free atoms 
(uniatomic molecules) or into less complex molecules. 

Relation of the Specific Heat of Elements to their Atomic Weights. 
— Reference may here appropriately be made to a physical fact of 
great importance as regards molecular and atomic weights. In the 
earlier pages of this manual it was stated that elements do not com- 
bine chemically in haphazard proportions, but in fixed weights ; and 
abundant evidence of the truth of the statement has already been 
afforded, and will also be found in this section on Quantitative An- 
alysis. Secondly, it has been shown that elements do not combine 
in haphazard proportions by volume, but in certain constant bulks : . 
and the weights of these bulks have been found to be identical with 
the combining weights themselves. Thirdly (this is the point to 
which attention is now drawn), if equal amounts of heat be given 
to elements in the solid state (that is, to solid elements or tosolid 
compounds of volatile elements), and the quantity of the element be 
increased or diminished until each is thus heated through an equal 
number of degrees, it will be found that the different weights of ele- 
ments required are (in relation to a common standard) identical with 
the combining weights of the elements and with the weights of the 
combining volume of the elements. Thus, where 108 parts of silver 
would be employed, 207 of lead would be necessary.- Hence, in the 

* Obviously, if equal weights of silver and lead were heated through 
an equal number of degrees, the silver would absorb nearly twice as 
much heat as the lead. In fact, as regards all the solid elements, "spe- 
cific heats and atomic weights are inversely proportional." This law 
was discovered by Dulong and Petit. It follows that the product o( 
the multiplication of the figures representing the specific heat of an 
element with the figures representing its atomic weight is, in the case 
of every such element, the same number. 



608 QUANTITATIVE ANALYSIS. 

determination of (a) combining proportion, (6) specific gravity in 
gaseous state, and (c) specific heat, three distinct methods of ascer- 
taining atomic weight are available. In cases where one method is 
inapplicable, recourse is had to either, or, if practicable, both, of the 
others, and thus the trustworthiness of observations and generaliza- 
tions placed more or less be^^ond question. The specific heat of a 
solid element is the same in the free as in the combined condition ; 
therefore the specific heat of a molecule is the sum of the specific 
heat of its constituent atoms. From the specific heat of a solid 
compound of a volatile element (chlorine, for example) can thus be 
calculated the specific heat of an element in the solid state, even 
though the free element cannot itself be solidified. For the pro- 
cesses by which experimentally to determine specific heat the reader 
is referred to books on Physics. 

There is equivalency, also, between electrical and chemical action. 
The amount of electricity which would set free 127 parts of iodine 
would set free 80 parts of bromine. 



QUESTIONS AND EXERCISES. 

983. Define specific weight, or, as it is commonly termed, specific 
gravity. 

984. In speaking of light and heavy bodies especially, what stand- 
ard of comparison is conventionally employed ? 

985. How are specific gravities expressed in figures ? 

986. Why should specific gravities be taken at one constant tem- 
perature ? 

987. How does the buoyancy of air affect the real weight of any 
material ? 

988. Describe the difference between density and specific gravity. 

989. Give a direct method for the determination of the specific 
gravity of liquids. 

990. A certain bottle holds 1 60 parts, by weight, of water or 135.7 of 
spirit of wine ; what is the specific gravity of the latter ? A us. 0.9046. 

991. An imperial fluidounce of a liquid weighs 366£ grains; what 
is its specific gravity ? Ans. .838. 

992. Equal volumes of benzol and glycerin weigh 34 and 49 parts 
respectively, and the sp. gr. of the benzol is 0.850 ; what is the spe- 
cific gravity of the glycerin ? Ans. 1.225. 

993. Explain the process employed in taking the specific gravity 
of solid substances in mass and in powder. 

994. State the method by which the specific gravity of a light 
body, such as cork, is obtained. 

995. "What modifications of the usual method are necessary in 
ascertaining the specific gravity of substances soluble in water? 

996. How is the specific gravity of gases determined ? 

997. By what law can the volume of a gas at any required pres- 
sure be deduced from its observed volume at another pressure? 

998. To what extent will 78 volumes of a gas at 22.3 inches 
barometer alter in bulk when the pressure, as indicated by the 
barometer, is 30.2 inches? 



SPECIFIC GRAVITY. 609 

999. Write a short account of the means by which the volumes of 
gases are corrected for temperature. 

1000. At the temperature of 15° C. 40 volumes (litres, pints, 
ounces, cubic feet, or other quantity) of a gas are measured. To 
what extent will this amount of gas contract on being cooled to the 
freezing-point of water (0° C.)? 

Answer. As 1 vol. of any gas at zero expands or contracts .003665 
of a vol. for each rise or fall of 1° C, 1 vol. at 0° C, if heated to 15° 
C, will become increased by .054975 (that is .003665 multiplied by 
15); 1 vol. will expand to 1.054975. Conversely, 1.054975 vol. will 
contract to 1 vol. if cooled from 15° C. to 0° C. And if 1.054975 
becomes 1 in cooling through 15° C, 40 vols, will (as found by rule 
of three) contract to 37.916. 

The following five problems and solutions are from Williamson's 
Chemistry : — 

1001. 10 litres of oxygen are measured off at 14° F. Required 
the volume of the gas at 15° C. 

Answer. The first operation must be to reduce the temperature 
quoted in Fahrenheit's degrees to an equivalent value on the Centi- 
grade scale. 14° F. is 18° below 32° F., the freezing-point of water, 
and a range of 9° on the Fahrenheit scale is equal to a range of 5° 
on the Centigrade scale, so that the temperature at which the oxygen 
is measured off is — 10° C. The rise of temperature up to 0° ex- 
pands the gas in such proportion that its volume at 0° is to its vol- 
ume at —10 as 1 is to 1 —0.03665 ; i. e. as 1 to 0.96335. The further 
rise of temperature from 0° C. to 15° expands the gas in the propor- 
tion of 1 to 1 + 15 X 0.003665 ; i. e. 1 to 1.054975. The total rise 
of temperature therefore expands the gas in the proportion of 
of 0.96335 to 1.054975. 

0.96335 : 1.054975 :- : 10. : x; 
. x = 10XL054975 
0.96335 

1002. 230 cubic centimetres of oxygen are measured off at 14° C. 
and 740 millimetres mercurial pressure. Required the volume of 
the gas at the normal temperature and pressure (0° C. and 760 
millimetres). 

Answer. Let the reduction for change of temperature be made 
first. The proportion 

1 + (14 X 0.003665) : 1 : : 230 : x 
gives 

230 m Q ^ . 

x= = 218./ 74. 

1.05131 

To reduce this volume of 740 millimetres pressure to the volume 
corresponding to the pressure of 760 millimetres, we have the 
proportion 

38 : 37 : : 218.77 : x; 
whence 

, = 37X218,77 =21302 . 
38 



610 QUANTITATIVE ANALYSIS. 

1003. A litre of oxygen is confined in a glass flask at 10° C. by the 
atmospheric pressure, added to that of a column of mercury 60 milli- 
metres high. The flask must be heated to 300° C. without any in- 
crease of volume taking place in the oxygen. How high must the 
column of mercury then be which presses on the gas, supposing the 
atmospheric pressure to remain constant at 760 millimetres ? 

Answer. The oxygen is given at 10° C. and 820 millimetres pres- 
sure. If the pressure remained constant, the rise of temperature 
from 10° C. to 300° C. would expand the gas in such proportion 
that 1.03665 volumes would expand to 2.0995 volumes. In order to 
prevent any expansion the pressure must be increased in the same 
proportion, whence 

1.03665 : 2.0995 : : 820 : x ; 

820X2.0995 irAnA 

/. x = — = 1660.6. 

1.03665 

From this total pressure the atmospheric pressure of 760 millimetres 
has to be deducted, leaving 900.6 millimetres as the height of the 
required mercurial column. 

1004. A litre of oxygen is required of the density of 100 at 0° C. 
What weight of potassic chlorate must be used for its preparation, 
and what total pressure must be applied to it ? 

Answer. The pressure required to compress oxygen from the den- 
sity of 16 to that of 100 is found by the proportion 

16 : 100 : : 760 : x ; 
76000 . 



16 



-. 4750. 



At the pressure of 4750 millimetres of mercury the weight of a litre 
of oxygen (16 grammes measure 11.2 litres at 0° C. and 760 millims. 
pressure) is found by the proportion 

760 : 4750 : : -I®- : x: 
11.2 
whence 

16 X 4750 Q no 
x = - — — — — = 8.93 grammes. 
11.2X760 & 

The weight of chlorate required for the evolution of 8.93 grammes 
of oxygen is found from the proportion 

48 : 122.5 : : 8.93 : x- 
.'. x = 22.8 grammes. 

1005. What is the volume of 12 grammes of hydrogen at 15° C? 

Answer. One gramme of hydrogen measures 11.2 litres at 0° C. ; 
therefore 12 grammes measure 12X11-2 = 134.4 litres at 0°. To 
find their volume at 15° C. we have the proportion 
1 : 1 + 15X0.003665 : : 134.4 : x: 



VOLUMETRIC QUANTITATIVE ANALYSIS. 611 

whence 

z = 134.4 X 1.054975 = 141.788 litres. 

1006. What interest for chemists have the specific heats of sub- 
stances ? 



VOLUMETRIC QUANTITATIVE ANALYSIS. 

Preliminary Note. — Great care should be observed in selecting a 
fair sample of any bulk of material that is to be examined either by 
volumetric or gravimetric quantitative analysis. If the whole quan- 
tity is in separate parcels, and there is any ground for believing that 
the parcels differ in quality, they should, if practicable, be carefully 
mixed, or, technically, " bulked." Small portions should be taken 
from different parts of the resulting heap and well mixed in a mortar 
or other vessel, or in certain cases dissolved and the solution well 
stirred or shaken. A specimen of the powder or a portion of the 
solution may then be selected for analysis. 

Introduction. — The operations of volumetric analysis consist (a) 
in carrying out some definite chemical reaction, already well known 
to the operator, with (b) definite quantities of chemicals or salts ; (c) 
the exact termination of the reaction between the two salts or chem- 
icals being ascertained — usually by some chemical indicator (litmus, 
starch, etc.). A portion of the chemical or salt, etc. to be tested is 
carefully weighed. To this is gradually added the second chemical 
or salt contained in the testing-fluid, commonly termed the Stand- 
ard Volumetric Solution. The usefulness and, indeed, the prepara- 
tion, of this Standard Solution is founded (as already indicated on 
page 521).on some accurate initial gravimetric operation. A iveighed 
amount of a pure salt is dissolved in a given volume of water. "Ac- 
curately measured quantities of such a Standard Volumetric Solu- 
tion will obviously contain just as definite amounts of the dissolved 
salt as if those amounts were actually iveighed in a balance, and, as 
measuring occupies less time than weighing, the volumetric opera- 
tions can be conducted with great economy of time as compared with 
the corresponding gravimetric operations." 

APPARATUS. 

The only special vessels necessary in volumetric quantitative oper- 
ations are — 1. A Hire flask (Fig. 73), which, when filled to a mark 
on the neck, contains 'at 15° C, or about <)0° F., one litre (1000 
cubic centimetres — ?'. e. 1000 grammes of water*) ; it serves for pre- 
paring solutions in quantities of one litre. 2. A tall cylindrical 
graduated litre jar (Fig. 72) divided into 100 equal parts; it serves 
for the measurement and admixture of decimal or centesimal parts 

* A cubic centimetre is, strictly speaking, the volume occupied by 
one gramme of distilled water at its point of greatest density — namely, 
4° C; metrical measurements, however, are uniformly taken at L5°.55 

C. (00° F.). 



612 



VOLUMETRIC QUANTITATIVE ANALYSIS. 



of a litre. 3. A graduated tube or burette (Fig. 74), which, when 
filled to "0, holds 100 cubic centimetres (a decilitre), and is divided 
into 100 equal parts ; it is used for accurately measuring small vol- 
umes of liquids. 



Fig. 72. 



Fig. 73. 



Fig. 74. 




A litre jar. 



A burette, etc. 



The best form of burette is Mohr's. It consists of a glass tube, 
commonly about the width of a little finger and the length of an 
arm from the elbow, contracted at the lower extremity and gradu- 
ated. The width and length of burettes, however, as well as the 
extent and fineness of their graduation, vary considerably. To the 
contracted portion is fitted a small piece of vulcanized caoutchouc 
tubing, into the other end of which a small spout made of narrow 
glass tube is tightly inserted. A strong wire clamp effectually pre- 
vents any liquid from passing out of the burette unless the knobs 
of the clamp are pressed by the finger and thumb of the operator, 
when a stream or drops flow at will. In place of the India-rubber 
tubing and clamp a stopcock is sometimes employed, and other 
modes of arresting the flow of liquid may be adopted. The accu- 
rate reading of the height of a solution in the burette is a matter 
of great importance ; it should be taken from the bottom of the 
curved surface of the liquid. It may be still more exactly meas- 
ured by the employment of a hollow glass float or bulb (Erdmann's 
float 5 see Fig. 74), of such a width that it can move freely in the 
tube without undue friction, and so adjusted in weight that it shall 
sink to more than half its length in any ordinary liquid. A fine 
line is scratched round the centre of the float ; this line must 
always be regarded as marking the height of the fluid in the 
burette. In charging the burette a solution is poured in, not 
until its surface is coincident with 0, but until the mark on the 
float is coincident with 0. 



ESTIMATION OF ALKALIES, ETC. 613 

ESTIMATION OF ALKALIES, ETC. 

Volumetric Solution of Oxalic Acid. 
(Crystallized Oxalic Acid, H 2 C 2 4 ,2H 2 == 126.) 

On account of the bivalent character of the oxalic radical, and the 
univalent character of most of the metals contained in the salts 
which are estimated by oxalic acid, it is convenient that each litre 
of the volumetric solution should contain half a molecular weight 
in grammes of the acid (H 2 C 2 4 ,2H 2 = 126 ~ 2 = 63). 

If pure crystallized oxalic acid be at hand, the solution is made 
by dissolving 63 grammes in water, and making the volume up with 
more water to exactly one litre. 

Pure oxalic acid, however, not being easy to obtain, the solution 
may be made from the commercial acid by dissolving 65 to 70 
grammes in enough water to make a litre of solution, and then de- 
termining the strength of this solution by a titration with pure car- 
bonate of sodium, making use of the following memoranda : — 

Na 2 C0 3 + H 2 C 2 4 ,2H 2 = Na 2 C 2 4 + C0 2 + 3H 2 



Pure anhydrous carbonate of sodium is easy to obtain, for com- 
mercial bicarbonate is usually of such purity that when a few 
grammes are heated to redness for a quarter of an hour the result- 
ing carbonate is practically free from impurity. The bicarbonate 
should, however, be tested, and if more than traces of chlorides 
and sulphates are present, these may be removed by washing a few 
hundred grammes, first with a saturated solution of bicarbonate of 
sodium, and afterward with pure distilled water. After drying, the 
salt is ready for ignition. 

About half a gramme of the carbonate of sodium is accurately 
weighed and placed in a half-pint flask, around the neck of which is 
tied calico or leather to protect the fingers when the heated vessel is 
shaken by the operator. The salt is dissolved in water to about 
one-third the capacity of the flask, and a few drops of the indicator, 
blue tincture of litmus, is added. The acid solution to be " set" or 
" standardized " is then poured into a burette, and run therefrom into 
the flask until the reddened litmus indicates the presence of free 
acid. This will be due in the first place to carbonic acid liberated 
and remaining dissolved in the solution. The contents of the flask 
are therefore boiled for several minutes, when the blue color will 
have returned. More acid is then run in until the mixture, after 
boiling, remains of a neutral color, indicating that just enough acid 
has been added to complete the reaction expressed in the foregoing 
equation. 

Let it be supposed that 0.6 gramme of carbonate of sodium was 

taken, and that this required II CO. of oxalic acid solution; how 

many c.c. of this solution would contain 63 grammes ol' oxalic acid 

crystals? or, what is equivalent in the reaction, how many c.c. would 

52 



614 VOLUMETRIC QUANTITATIVE ANALYSIS. 

be required to neutralize 53 grammes of carbonate of sodium ? As 
0.6 gramme Na 2 C0 3 is to 11 c.c. sol., so are 53 grammes Na 2 C0 3 to 
x e.c. sol. ; x = 972 c.c. 972 c.c. (nearly) are equivalent to 53 grammes 
of carbonate of sodium, and contain 63 grammes of oxalic acid. 

This solution may either be used as it is, or may be diluted with 
water, every 972 c.c. to be diluted to 1000 c.c, so that 1000 c.c. shall 
contain 63 grammes of oxalic acid. 

The following official substances are tested by this solution accord- 
ing to the United States Pharmacopoeia : — 

Solutions of Ammonia. — 2 or 3 grammes of dilute, or about 1 
gramme of strong, solution of ammonia is a convenient quantity to 
operate upon. The weighing is most conveniently accomplished by 
taking a small stoppered bottle containing half an ounce or so of 
the substance, and, having ascertained its total weight, transfer 
about the quantity desired to the flask in which the estimation is 
to be conducted, and again weigh the bottle with what remains in 
it. The difference is the exact quantity taken. The weighing of 
the ammonia solution having been accomplished, water is added to 
about one-third the capacity of the flask (or, better, the ammonia is 
added to water already in the flask), and a few drops of tincture of 
litmus introduced. The titration is then conducted as described be- 
fore, except that no heat is employed. 

2NH 4 HO + H 2 CA,2H 2 = (NH 4 ) 2 C 2 4 + 4H 2 
2)70 2)126 

35 63 = grammes in 1000 c.c. of standard solution. 

2NH 3 H 2 + H 2 C 2 4 ,2H 2 = (NH 4 ) 2 C 2 4 + 4H 2 
2)34 2)126 

17 63 = grammes in 1000 c.c. of standard solution. 

1000 c.c. of standard solution, or its equivalent of a solution of 
any other strength, would, according to this reaction, neutralize 17 
grammes of ammonia gas (NH 3 ) or 35 grammes of hydrate of am- 
monium (NH 4 HO). If 3 grammes of ammonia solution had been 
taken, and it had required 15 c.c. of standard oxalic acid solution, 
then the amount of ammonia gas or hydrate of ammonium it con- 
tained would be seen by the following calculations : — 

1000 c.c. : 17NH 3 : : 15 c.c. : x = .255 grammes NH 3 
1000 c.c. : 35NH 4 HO : : 15 c.c. : x = .525 grammes NH 4 HO 

Three grammes, then, would contain .255 grammes of the gas or 
.525 grammes of hydrate of ammonium. Or, in percentage, 

3gr.sol.:.255gr.NH 3 :: lOOgr. sol.:xgr.NH s = 8.5%NH 3 
'3gr.sol. : .525 gr. NH 4 HO : : 100 gr. sol. : zgr. NH 4 HO = 17.5%NH 4 HO 

The solution would therefore contain 8.5 per cent, of ammonia gas 
(NH 3 ) or 17.5 per cent, of hydrate of ammonium (NH 4 HO). If the 
oxalic acid solution was not of full standard, the number of c.c. which 
contained 63 grammes of oxalic acid — which was, in fact, equivalent 



ESTIMATION OF ALKALIES, ETC. 615 

to 1000 c.c. of standard solution — would be substituted for 1000 c.c. 
in the preceding proportions. 

A comparison should now be made with the requirements of the 
Pharmacopoeia. It is useful to express results as percentage of sub- 
stance of pharmacopoeial strength in the material examined. Thus 
the U. S. Pharmacopoeia requires dilute ammonia solution (both Aqua 
Ammonice and Spiritus Ammonia?) to contain 10 per cent, of the gas 
(NH 3 ). The solution supposed to have been operated on contained 
8.5 per cent. NH 3 (10 : 8.5 : : 100 : x = 85). Therefore it contains 85 
per cent, of the dilute ammonia of the U. S. Pharmacopoeia.* 

Strong Solution of Ammonia, U. S. P., contains 28 per cent, of 
ammonia gas (NH 3 ). 

Note. — The calculations just described for ammonia are similar to 
those employed throughout volumetric analysis ; they will not be re- 
peated, therefore, in the case of every substance. 

Carbonate of Ammonium. — The reactions indicated by the fol- 
lowing equations occur between commercial carbonate of ammonium 
and oxalic acid : — 



2N 3 H U C 2 5 + 3H 2 C 2 4 ,2H 2 = 3(NH 4 ) 2 C 2 4 + 8H 2 + 4C0 2 




grammes in 1000 c.c. of standard solution. 



About 1 gramme is a convenient quantity to operate upon. Tinc- 
ture of litmus is the indicator, and the titration is conducted at a 
temperature just short of boiling. The estimation is not very satis- 
factory, because the heat employed, while scarcely sufficient to expel 
the carbonic acid gas, is enough to occasion loss of ammoniacal salt. 
Practised analysts usually add excess of the standard acid, and thus 

* Extremely minute quantities of ammonia — 1 part in many millions 
of water — may be estimated volumetricallv by adding excess of a color- 
less, strongly alkaline solution of red iodide of mercury (Nessler's 
test), then in a similar vessel, containing an equal amount of pure 
water with excess of the Nessler reagent, imitating the depth of yellow 
or reddish-yellow color thus produced by adding an ammoniacal solu- 
tion of known strength. The amount of ammonia thus added represents 
the amount in the original liquid. 

The Nessler Reagent. — A litre may be made by dissolving 30 or 40 
grammes of iodide of potassium in a small quantity of hot water, add- 
ing a strong hot solution of perchloride of mercury until the precip- 
itate of mercuric iodide ceases to redissolve even by the aid of rapid 
stirring and heat, slightly diluting, filtering, adding a strong solu- 
tion of (120 to 140 grammes) caustic soda or (160 to 180 grammes) 
caustic potash, and diluting to 1 litre. A few c.c. (5 or 6 or more) oi' a 
strong solution of perchloride of mercury are finally stirred in, the 
whole set aside till all precipitated red iodide has deposited, and the 
clear liquid decanted for use. The reaction of this Nessler test with 
ammonia is as follows: — 

NII 3 -I 2HgI a + 3KHO = NHg 2 I + 3KI + 311 ,0. 
Potassio-morcurie Iodide, without alkali, is commonly known as 
Mayer's Reagent, HgI 2 2KI. 



G16 VOLUMETRIC QUANTITATIVE ANALYSIS. 

fix every trace of ammonia ; then gently boil to get rid of carbonic 
acid gas ; bring back the liquid to neutrality by an observed volume 
of standard alkaline solution, and deduct an equivalent volume of 
acid from the quantity first added. The United States Pharmaco- 
poeia requires 5.232 grammes to neutralize 100 c.c. of standard solu- 
tion of oxalic acid. This corresponds to 100 per cent, of carbonate 
having the formula N 3 H n C 2 5 . 

Borax. — Two or three grammes is a convenient quantity. 

Na 2 B 4 O 7 ,10H 2 O + H 2 C 2 4 ,2II 2 = Na 2 C 2 4 + H 2 B 4 7 + 12H 2 



2 )382 2)126 

191 63 = grammes in 1000 c.c. of standard solution. 

Tincture of litmus is the indicator, and the titration may be carried 
on without heat. The liberation of boracic acid colors the litmus 
wine-red. This is not regarded, the titration being continued until 
the bright red due to the action of free oxalic acid makes its appear- 
ance. Both the British and United States Pharmacopoeias require 
borax to be pure (= 100 per cent.). 

Lead Acetate and Solution of Subacetate. — Operate upon about 
three grammes of acetate of lead and from five to ten grammes of 
solution of subacetate. 

Pb2C 2 H 3 2 ,3H 2 + H 2 C 2 4 ,2H 2 = PbC 2 4 + 2HC 2 H 3 2 + 5H 2 

2 )378.5 2 )126 

189.25 63 = grammes in 1000 c.c. of standard solution. 

Pb 2 02C 2 H 3 2 + 2(II 2 C,0 4 ,2H 2 0) = 2PbC 2 4 + 2IIC 2 H 3 2 + 5H 2 
4 ML i)252~ 

136.75 63= grammes in 1000 c.c. of standard solution. 

The flask in which the estimation is being conducted should contain 
one third of a flaskful of water. In the case of both acetate and 
solution of subacetate of lead a little acetic acid should be added to 
prevent precipitation of basic salt on dilution. The only indicator 
of complete reaction is cessation of production of the precipitate — 
oxalate of lead. The United States Pharmacopoeia requires acetate 
of lead to be pure (100 per cent.), and solution of subacetate to con- 
tain 25 per cent. 

Lime- Water and Saccharated Solution of Lime. — Measure about 
half a litre of lime-water for the estimation, and of saccharated 
solution weigh about 25 grammes. The following equations, etc. 
are quantitative expressions of the reactions : — 

Ca2HO -4- H,C 2 4 = CaC 2 4 + 2H 2 

2)126 

63 = grammes in 1000 c.c. of standard solution. 



ESTIMATION OF ALKALIES, ETC. 617 

Or, 

CaO,H 2 + H 2 C 2 4 = CaC 2 4 + 2H 2 

2)56 2)126 

28 63 = grammes in 1000 c.c. of standard solution. 

Litmus is used as an indicator. 

Caustic Potash and Soda, Potassium and Sodium Carbonates and 
Bicarbonates . — Litmus is the indicator throughout, and heat is used 
in all cases, for the caustic alkalies always contain some carbonate. 

2KHO + H 2 C 2 4 ,2H 2 = K 2 C 2 4 + 4H 2 
2)112 2)126 

56 63 = grammes in 1000 c.c. of standard solution. 

2NaIIO + H 2 C 2 4 ,2H 2 = Na 2 C 2 4 + 4H 2 
2)80 2)126 

40 63 = grammes in 1000 c.c. of standard solution. 

K 2 C0 3 + H 2 C 2 4 ,2H 2 = K 2 C 2 4 + C0 2 + 3H 2 
2)138 2)126 

69 63 = grammes in 1000 c.c. of standard solution. 

Or, 

K 2 C0 3 + 16%H 2 + H 2 C 2 4 ,2H 2 = K 2 C 2 4 + C0 2 + xH 2 

2)16L28 2)126 

^82.14 63 = grammes in 1000 c.c. of standard solution. 

Na 2 C0 3 + H 2 C 2 4 ,2H 2 = Na 2 C 2 4 + C0 2 + 3H 2 
2) 106 2)126 

53 63 = grammes in 1000 c.c. of standard solution. 

Or, 

Na 2 C0 3 ,10H 2 + H 2 C 2 4 ,2H 2 = Na 2 C 2 4 + C0 2 + 13H 2 

2)286 2)126~ 

143 63 = grammes in 1000 c.c. of standard solution. 

2KIIC0 3 + H 2 C 2 4 ,2H 2 = K 2 C 2 4 + 2C0 2 + 4H 2 
2)200 2)126 

100 63 = grammes in 1000 c.c. of standard solution. 

2NalIC0 3 + II 2 C 2 4 ,2II,0 = Na 2 C 2 4 + 2C0 2 + 4II 2 
2)168 2)126 

84 63 = grammes in 1000 C.C. of standard solution. 

Convenient quantities to operate with arc: Of caustic potash, 
1 gramme; caustic soda, .5 to 1 gramme; potassium carbonate or 



618 VOLUMETRIC QUANTITATIVE ANALYSIS. 

bicarbonate, 1 to 2 grammes ; sodium carbonate or bicarbonate, 
2 to 3 grammes ; dried sodium carbonate, .5 to 1 gramme ; and of 
solutions a corresponding quantity. The United States Pharma- 
copceial requirements are : Caustic potash or soda, 90 per cent, 
of KHO or NallO ; potassium carbonate, 81 per cent, of K 2 C0 3 ; 
sodium carbonate, 98 per cent, of Na 2 CO 3 ,10H 2 O ; potassium bicar- 
bonate, 100 per cent, of KHC0 3 ; sodium bicarbonate, 99 per cent, 
of NaHC0 3 5 and commercial bicarbonate, at least 95 per cent. The 
dried carbonate (Sodii Carbonas Exsiccatus, U. S. P.) is to contain 
72.0 per cent, of real carbonate. Liquor Potassce and Liquor Sodce 
must contain 5 per cent, of pure hydrate. 

The strength of soda-ash is often reported in terms of "soda" — 
that is, oxide of sodium (Na 2 = 62). The old molecular weight 
of carbonate of sodium, 54 (it should have been 53), derived from 
that of " soda," 32 (it should have been 31), is still employed in 
Great Britain in reporting the strength of soda-ash. The true 
amount of soda equivalent to 54 parts of carbonate is 31.41 parts. 
A modern analyst having found the true amount of soda in a sample 
of soda-ash is expected by some manufacturers to report 31 as 31.41 
parts, or 53 of carbonate as 54, and other quantities in proportion 
to thes • figures. 

Tartrates and Citrates of Potassium and Sodium and Acetate of 
Potassium. — When tartrates or citrates of alkali-metals are burned 
in the open air the whole of the metal remains in the form of 
carbonate. Each molecular weight of a neutral tartrate gives one 
molecular weight of carbonate, and every two molecular weights of 
an acid tartrate give one molecular weight of carbonate. Advantage 
is taken of these reactions to estimate indirectly the quantity of 
citrate or tartrate in presence of substances with which they are 
generally associated. One to two grammes of any of these salts is 
a convenient quantity to operate upon. The ignition may be con- 
ducted in a platinum or porcelain crucible. A low red heat only 
should be used, and the vessel removed when complete carbonization 
has been effected — that is to say, when nothing remains but the 
carbonate and free carbon. The mixture is in this case treated with 
hot water, and the carbon separated by filtration. If too little heat 
has been used and carbonization is not complete, the filtrate will be 
more or less colored. If this should be the case the operation must 
be repeated with a fresh quantity of material. The carbonate is 
titrated in the usual way. The following equations, etc. explain 
the reactions : — 

2K 2 C 4 H 4 O fi ,H 2 _j_ 50 2 = 2K 2 C0 3 + 6C0 2 + 4H 2 



4)470 4)276 

1 17.5 69 = 1000 c.c. of standard oxalic acid solution. 

2KIIC 4 II 4 6 + 50 2 = K 2 C0 3 + 7C0 2 + 5H 2 
2) 376 2 )138 

188 69 = 1000 c.c. of standard oxalic acid solution. 



ESTIMATION OF ALKALIES, ETC. 619 

2(K 3 C 6 H 5 7 ,H 2 0) + 90 2 = 3K 2 C0 3 + 9C0 2 + 7H 2 




6 )648 6 )414 

1 08 69 = to 1000 c.c. of standard oxalic acid solution. 

2(KNaC 4 H 4 6 ,4H 2 0) + 50 2 = 2KNaC0 3 -}- 6C0 2 + 8H 2 
4 )244 

61 =1000 c.c. of standard oxalic acid sol. 

= K 2 C0 3 +3C0 2 + 3H 2 
2 )138 

69 = 1000 c.c. of standard oxalic acid solution. 

It will be readily understood that in the first (for example) of the 
reactions just expressed 113 weights of tartrate of potassium are 
equivalent to 69 weights of carbonate of potassium ; and as in a 
previous reaction it has been shown that 69 weights of carbonate of 
potassium are equivalent to 63 weights of oxalic acid, it follows that 
113 weights of tartrate of potassium are equivalent to 63 weights of 
oxalic acid. Let these weights be grammes, and then 113 grammes 
of tartrate of potassium are equivalent to 63 grammes of oxalic 
acid, or to 1000 c.c. of the standard solution of oxalic acid. If the 
substance estimated be a crude sample of tartrate of potassium, and 
the number of c.c. of oxalic acid used has been 15 c.c, then as 1000 
c.c. of the acid solution are to 113 grammes of tartrate of potassium, 
so are 15 c.c. of the solution to 1.695 grammes of tartrate of potas- 
sium. Now, if the weight of the sample taken was 2 grammes, 
then as 2 grammes of the sample contain 1.695 of real tartrate of 
potassium, 100 will contain x = 84.75 per cent, of real tartrate. 
These salts are required to be 100 per cent, pure by the United 
States Pharmacopoeia, except acetate of potassium, which is to have 
98 per cent, of real acetate. Trade samples are practically pure as 
a rule. If sulphate of calcium be present in tartrates or citrates, 
loss of carbonate of potassum will ensue, sulphate of potassium 
being formed. In estimating acid tartrate of potassium, which is 
the salt most likely to contain sulphate of calcium, direct titration 
without ignition may be followed. 

Permanganate of Potassium. — The reaction is shown in the fol- 
lowing equation : K 2 Mn 2 8 + 3H 2 S0 4 + 5(II 2 C 2 4 ,2H..O) = K.,S(V- 
+ 2MnS0 4 + 18H 2 + 10CO 2 . 

K 2 Mn 2 8 and f)(TI,0,0,,2II,0) 
10)630 

63 = grammes in 1000 C.C, of standard solution. 

The salt satisfies official requirements if it contains 98.8 per cent, of 
real permanganate of potassium. 



620 VOLUMETRIC QUANTITATIVE ANALYSIS. 

Notes. 

Alkalimetry. — The foregoing processes are often spoken of as those 
of alkalimetry (the measurement of alkalies). 

Neutral solution of litmus is prepared by digesting the commercial 
fragments in about 1 5 or 20 times their weight of water for a few hours, 
decanting, dividing into two equal portions, adding acid to one till it 
is faintly red, then pouring in the other and mixing. The solution 
may be kept in a stoppered bottle and occasionally exposed to the air. 
It should never be filtered, but gradually allowed to deposit. 

Standard sulphuric acid may be used in the place of oxalic acid, 
1000 c.c. of the liquid containing half of the molecular Aveight of 
the pure acid in grammes. It is prepared by diluting oil of vitriol 
with from 3 to 4 times its bulk of distilled water, ascertaining how 
much of the acid liquid is required to exactly neutralize -£$ of the 
molecular weight of pure carbonate of sodium, taken in grammes 
(5.3), and adding water until the observed volume of acid is in- 
creased to 100 c.c, the whole of the fluid being similarly diluted. 

Weighing. — In the case of substances which are liable to alter by 
exposure to air it is important that a selected quantity should be 
quickly weighed, rather than selected weights be accurately balanced 
by material, the former operation occupying much the shorter time. 

Salts other than the official may be quantitatively analyzed by the 
volumetric solutions of the Pharmacopoeia, slight modifications of 
manipulation even enabling the processes to be adapted to fresh 
classes of salts. Ample instructions for extending operations in this 
manner will be found in Sutton's Handbook of Volumetric Analysis. 



QUESTIONS AND EXERCISES. 

1007. Describe the various pieces of apparatus used in volumetric 
determinations. 

1008. One hundred cubic centimetres of solution of oxalic acid con- 
tain 6.3 grammes of the crystallized acid : work sums showing what 
weights of bicarbonate of potassium and anh}*drous carbonate of sodium 
that volume will saturate. Ans. 10 grammes and 5.3 grammes. 

1009. Show what weight of hydrate of potassium is contained in 
solution of potash. 48.02 grammes of which are saturated by 50 c.c. 
of the standard solution of oxalic acid. Ans. 5.83 per cent. 

1010. Calculate the percentage of hydrate of calcium in lime-water, 
438 grammes of which are neutralized by 20 c.c. of the volumetric 
solution of oxalic acid. Ans. 0.1689. 

1011. Eight grammes of a sample of Rochelle salt, after ignition, 
etc., require 54.3 c.c. of the official oxalic acid solution for complete 
saturation ; work sums showing what is the centesimal proportion 
of real salt present. Ans. 95.7. 



ESTIMATION OF ACIDS. 



In the previous experiments a known amount of an acid has been 
used in determining unknown amounts of alkalies. In those about 



ESTIMATION OF ACIDS. G21 

to he described a known amount of an alkali is employed in esti- 
mating unknown amounts of acids. The alkaline salt selected may 
be either a hydrate or a carbonate ; but the former is to be pre- 
ferred, for the carbonic acid set free when a strong acid is added to 
a carbonate interferes to some extent with the indications of 
alkalinity, acidity, or neutrality afforded by litmus. The alkali 
most convenient for use is soda, a solution of which has probably 
already been made the subject of experiment in operations with the 
standard solution of oxalic acid. It should be kept in a stoppered 
bottle and exposed to air as little as possible. 



Volumetric Solution of Soda. 

(Hydrate of Sodium, NaHO = 40.) 

This aqueous solution of soda is most conveniently made of such 
a strength that each 1000 c.c. contains one molecular weight in 
grammes of the alkali (NallO = 40). It will be seen from the fol- 
lowing equation that 40 grammes of soda convert 63 grammes of 
oxalic acid into neutral oxalate of sodium. Therefore, 1 litre of 
this solution, containing 40 grammes of soda, will form a neutral 
solution of oxalate with 1 litre of standard oxalic acid solution, 
or with a chemically equivalent quantity of oxalic acid solution of 
any other strength. 

II 2 C 2 4 ,2II 2 + 2NaIIO = Na 2 C 2 4 + 4H 2 

2)126 2 )80 

63 = 1000 c.c. of stand, sol. 40 = 1000 c.c. of standard solution. 

If pure soda were at hand, it would only be necessary to weigh 
40 grammes, dissolve this in water, and dilute to 1 litre. But 
pure soda cannot readily be produced. Therefore weigh about 45 
grammes of hydrate of sodium of trade, and add water to 1 litre. 
When dissolved take, say, 14 c.c, dilute with more water in a flask, 
add a few drops of tincture of litmus, and titrate with oxalic acid 
solution of known strength. Suppose that the volume of standard 
acid solution required to neutralize the 14 c.c. of soda solution the 
strength of which is to be estimated has been 15 c.c, or an equiva- 
lent amount of acid solution of another strength ; then, how many 
c.c of soda solution is equivalent to 1000 c.c of standard acid solu- 
tion ? or, what comes to the same thing, how many C.C. of soda solu- 
tion contain 40 grammes of real soda. (XallO)? As 15 c.c. stand- 
ard acid are to 14 c.c soda solution, so arc 1000 c.c. standard arid 
to x c.c. sc = 933 c.c 933 C.c. of the soda solution contain, there- 
fore, 40 grammes of soda, This may cither be diluted, every 933 
c.c. to L000 c.c, so that it may be standard (1000 c.c. 40 grammes 
NallO), or the solution may he used without dilution (933 C.C. -10 
grammes NallO). It has already been mentioned that soda nearly 
always contains carbonate. To remove resulting carbonic acid, 
therefore, gentle heat should be employed toward the close of each 



622 VOLUMETRIC QUANTITATIVE ANALYSIS. 

titration in all the estimations with this solution. Litmus is used 
throughout as an indicator of completion of the reaction. The 
following substances are officially estimated with this solution. 
The list admits of considerable extension (see Sutton's Volumetric 
Analysis). 

Acetic Acid. — Operate upon about 1 gramme of glacial acid, 
about 20 grammes of dilute acid, or about 3 grammes of ordinary 
acetic acid. 

NaHO = NaC 2 H 3 2 + H 2 

40 = 1000 c.c. standard solution. 

Acetic Acid, U. S. P., should contain 36 per cent of real acid 
(HC 2 H 3 2 ) ; Dilute Acetic Acid, U. S. P., 6 per cent ; Glacial 
Acetic Acid, U. S. P., 99 per cent. 

Citric Acid. — Operate on about 1 gramme. The reaction is ex- 
pressed by the following equation, etc. : — ■ 

H 3 C 6 H 5 7 ,H 2 + 3NaHO = Na 3 C 6 H 5 7 + 4H 2 
3)210 3 )120 

70 40 = 1000 c.c. standard solution. 

Citric Acid, U. S. P., should be pure (= 100 per cent. 
H 3 C 6 H 5 7 ,H 2 0). 

Hydrochloric Acid. — Operate on from 1 to 2 grammes of the con- 
centrated acid or on about 4 grammes of the dilute acid. 

NaHO = NaCl + H 2 

40 = 1000 c.c. standard solution. 

Hydrochloric Acid, U. S. P., should contain 31.9 per cent, of real acid 
(HC1), and Dilute Hydrochloric Acid, U. S. P., 10 per cent. 
Dilute Hydrobromic Acid. — Operate on from 8 to 12 c.c. 

HBr + NaHO = NaBr -j- H 2 

80.8 40 = 1000 c.c. standard solution. 

Dilute Hydrobromic Acid, U. S. P., should contain 10 per cent, of 
real acid (HBr). 

Lactic Acid. — Operate on 1.5 to 2 grammes. The reaction is ex- 
pressed by the following equation : — 

HC 3 H 5 3 + NaHO = NaC 3 H 5 3 + H 2 

90 40 = 1000 c.c. of standard solution. 

Lactic Acid, U. S. P., should represent 75 per cent, of absolute lactic 
acid (HC 3 H 5 3 ). 

Nitric Acid. — Operate on from 1 to 2 grammes of concentrated or 
on from 4 to 5 grammes of dilute acid. 



ESTIMATION OF ACIDULOUS RADICALS. 623 

HN0 3 + NaHO = NaN0 3 + H 2 

63 40 = grammes in 1000 c.c. standard solution. 

Nitric Acid, U. S. P., should contain 69.4 per cent., and Dilute Nitric 
Acid, U. S. P., 10 per cent., of real acid (HN0 3 ). 

Sulphuric Acid. — Operate upon from .5 to 1 gramme of concen- 
trated acid or from 4 to 5 grammes of either Dilute or Aromatic Sul- 
phuric Acid. 

H 2 S0 4 + 2NaHO = Na 2 S0 4 + 2H 2 
2)98 2)80 

49 40 = grammes in 10U0 c.c. standard solution. 

Sulphuric Acid, U. S. P., should contain not less than 96 per cent., 
Dilute, U. S. P., 10 per cent, of real acid, and Aromatic, U. S. P., 
18 per cent., of sulphuric acid (H 2 S0 4 ), partly as ethyl-sulphuric 
acid. 

Tartaric Acid. — Operate upon about 1 gramme of the acid. The 
following equation, etc. represents the reaction : — 

H 2 C 4 H 4 6 + 2NaHO = = Na 2 C 4 H 4 6 + 2H 2 
2 )150 

75 40 = grammes in 1000 c.c. standard solution. 

Tartaric Acid, U. S. P., should contain 100 per cent, of H 2 C 4 H 4 6 . 

Notes. — 1. Pure acetates, citrates, more especially, tartrates, and 
some other organic salts have an alkaline action on litmus, but not 
to an important extent. If the soda solution be added to acetic, 
citric, or tartaric acid containing litmus until the liquid is fairly 
blue, the operator will obtain trustworthy results. In delicate experi- 
ments turmeric, "methyl-orange," " phenolphthalein," etc. may be 
used instead of litmus. 

2. The operations for the quantitative analysis or measurement of 
acids are often collectively spoken of under the name of acidimetry. 



QUESTIONS AND EXERCISES. 

1012. Calculate the percentage of real acid present in diluted sul- 
phuric acid, 30 grammes of which are neutralized by 84 c.c. of the 
official volumetric solution of soda. Ans. 13.72. 

1013. Show how much real nitric acid is contained in a solution 
36 grammes of which are saturated by 94 c.c. of the standard solu- 
tion of soda. Ans. 16.45 per cent. 



ESTIMATION OF ACIDULOUS RADICALS PRECIP- 
ITATED BY NITRATE OF SILVER. 

The purity of many salts and the strength of their solutions may 
be determined by this process. Diluted Hydrocyanic Acid, Bromide 



624 VOLUMETRIC QUANTITATIVE ANALYSIS. 

of Potassium, Bromide of Ammonium, Cyanide of Potassium, Bro- 
mide of Sodium, Syrup of Hydriodic Acid, Syrup of Bromide of 
Iron, and Syrup of Iodide of Iron are quantitatively analyzed by 
standard solution of nitrate of silver. 

Standard Solution of Nitrate of Silver. 

(Nitrate of Silver, AgN0 3 = 169.7.) 

Dissolve 16. 97 grammes of crystals of pure nitrate of silver 

in 1 litre of water. 1000 c.c. of this solution contain -J^- of 

the molecular weight in grammes of nitrate of silver. It is 

therefore a decinormal solution. 

Pure crystals of nitrate of silver can readily be obtained. When 
this is not the case, and pure chloride of sodium is at hand, a solu- 
tion may be made of approximate strength, and then be standardized 
by means of that salt. The method may be thus indicated : — 
NaCl + AgN0 3 = AgCl + NaN0 3 

10)58.5 10) 169.7 

5.85 16.97 = grammes in 1000 c.c. of standard solution. 

Take rather less than 1 gramme of the chloride of sodium (NaCl) 
and dissolve in water. The salt (AgCl) precipitated in the reaction 
is an insoluble salt, and the end of its precipitation will serve as a 
good indication of the completion of the reaction. A better in- 
dicator, however, is a few drops of neutral chromate of potassium 
(which should previously be purified by recrystallization). The 
nitrate of silver does not act upon the chromate until all the chlo- 
ride is converted into chloride of silver, after which a deep-red pre- 
cipitate of chromate of silver is produced. This indication is ex- 
tremely delicate, and in practice is noticed when the white color due 
to chloride of silver changes to yellowish from formation of the first 
traces of chromate of silver. The titration being accomplished, sup- 
pose that .1 gramme of the chloride of sodium has taken 17 c.c. of 
the nitrate of silver solution of unknown strength ; how many c.c. 
of the solution are equivalent to 5.85 of the chloride of sodium ? 
that is, how many c.c. of solution contain 16.97 grammes of nitrate 
of silver? As .1 gramme of NaCl is to 17 c.c, so are 5.85 NaCl 
to x c.c. = 994 c.c. 994 c.c. of the solution of nitrate of silver are 
equivalent, therefore, to 1000 c.c. of official standard solution, and 
contain 16.97 grammes of the nitrate of silver. They may be di- 
luted to 1000 c.c. if desired. 

Hydrocyanic Acid. — Three to four grammes of the dilute acid 
form a convenient quantity to operate upon. The HCN is first 
converted into KCN or NaCN with potash or soda. The following 
equations, etc. explain the reactions : — 

2HCN 4- 2NaIIO = 2NaCN + 2ILO 



ESTIMATION OF ACIDULOUS RADICALS. 625 

2NaCN + AgN0 3 = AgCN,NaCN + NaNO s 
10)169.7_ 

16.97 = grammes in 1000 c.c. of standard solution. 

It is seen that 5.4 grammes of real hydrocyanic acid (HCy) are 
equivalent to 9.8 grammes of cyanide of sodium, and represent 
16.97 grammes of nitrate of silver, or 1000 c.c. of standard solution 
of nitrate of silver. 

The cyanide of sodium having been obtained, the titration is carried 
on until it is converted into the soluble double salt (NaCy,AgCy), 
immediately after which a permanent turbidity occurs, due to pre- 
cipitation of cyanide of silver, thus : — 

AgCy,NaCy + AgN0 3 = 2AgCy + NaN0 3 . 

This turbidity affords a delicate and satisfactory proof of the com- 
pletion of the above reaction, which is the B. P. process. 

There is, however, a difficulty in the conversion of the acid into 
the cyanide (Siebold) to which it is necessary to pay particular atten- 
tion. Tincture of litmus is added to the acid diluted largely with 
water, and the soda poured in. Owing to the strong alkaline reac- 
tion of the cyanide of sodium formed, the mixture becomes blue 
when only a small proportion of the acid has been converted. If 
then the titration be conducted until the turbidity appears, only the 
cyanide of sodium will be estimated, leaving free hydrocyanic acid 
still unacted upon. Indeed, cyanide of sodium may be estimated in 
presence of hydrocyanic acid in this way. Thus the following reac- 
tion (expressed approximately) might occur : 

NaCy + 4HCy + AgN0 3 = AgCy + NaN0 3 + 4HCy 

Alkaline. Turbid and acid. 

In this case only one-fifth of the acid originally present would be 
estimated. The mixture would, however, become acid. If this 
acidity be prevented all difficulty is overcome. The following de- 
tails (Senier) will be found to answer well : To the diluted hydro- 
cyanic acid add soda solution to a strong alkaline reaction, deter- 
mined by means of tincture of litmus. Then add the silver solution, 
drop by drop, from the burette, when in most cases the mixture will 
become acid. When it does so, add more soda solution, and repeat 
this process until the final reading, when the solution must be alka- 
line. In this way the addition of too much soda at the commence- 
ment, which would use up silver solution and make the reading a 
trifle too high, is avoided. 

Dilute Hydrocyanic Acid, U. S. P., should contain 2 per cent, of 
real acid (HON), as shown by the following process: — 

The following is the quantitative test of purity ordered by the 
United States Pharmacopoeia: — "6.75 gm. diluted with 30 c.c. of 
water, and mixed with enough of an aqueous suspension of mag- 
nesia to make the mixture quite opaque, and afterward with a few 
drops of solution of chromate of potassium, should require 50 c.c. of 



626 VOLUMETRIC QUANTITATIVE ANALYSIS. 

the volumetric solution of nitrate of silver before the red color 
caused by the latter ceases to disappear on stirring (corresponding 
to the presence of 2 per cent, of absolute Hydrocyanic Acid)." By 
this method the whole of the HCy is precipitated as AgCy before the 
chromate of silver is permanertly precipitated. 

Bromide of Ammonium. — Operate upon .075 to .1 gramme of the 
salt, using chromate of potassium (or Bichromate, U. S. P.) as an 
indicator of the close of the reaction : — 

NH 4 Br + AgN0 3 = AgBr + NH 4 N0 3 . 

10 )97.8 10)169.7 

9.78 16,97 = 1000 c.c. of standard solution. 

Bromide of Ammonium, U. S. P., should be of 97 per cent, purity, 
but as the impurity is chloride of ammonium, this too will be pre- 
cipitated by the nitrate of silver, and must be calculated in finding 
the percentage of bromide. 

NH 4 C1 + AgN0 3 = AgCl + NH 4 NO s . 
1 0)53.5 10 )169.7 

5.35 16.97 = 1000 c.c. of standard solution. 

The amount of the salt equivalent to 1000 c.c. of standard solution 
is first calculated by simple proportion : Let x represent this ; then 
9.78 — x=y, the excess of standard solution used up by the chloride 
of ammonium, reckoned in terms of bromide (XH 4 Br) ; and since 
5.35 grammes of NH 4 C1 = 9.78 grammes of NH 4 Br, the excess 
which ammonium chloride can consume is represented by 9.78 — 
5.35=4.43; 

therefore, as 4.43 : 5.35 : : y : z = the amount of chloride of am- 
monium present in x grammes of the sample taken ; lastly, the per- 
centage is calculated by simple proportion : 

Asa; : 100 : : z : p = percentage. For example: .075 gramme 
of the salt required, 7.8 c.c. of standard solution, 

1. 7.8 : 1000 : : .075 : x: 

x = 9M5. 

2. 9.78 — 9.615 = ?/5 

# = .165. 

3. 4.43 : 5.35 : : .165 : g; 

2 = .19926. 

4. 9.615 : 100 : : .19926 : p) 

^ = 2.072 per cent, of NH 4 C1. 

Bromide of Potassium. — Operate upon rather less than .1 
gramme, and conduct the titration in the same manner as with 
chloride of sodium, using chromate of potassium as an indicator 
of the close of the reaction : — 



ESTIMATION OF ACIDULOUS RADICALS. 627 

KBr + AgN0 3 = AgBr + KN0 3 
10)118.8 10)169.7 

11.88 16.97 = grammes in 1000 c.c. of standard solution. 

To calculate the KC1, proceed as for NH 4 C1, 74.5 of KC1 being 
equal to 118.8 of KBr. 

The United States Pharmacopoeia requires Bromide of Potassium 
to contain 97 per cent, of the salt. 

Bromide of Sodium. — Operate upon .1 gramme, and proceed 
exactly as for bromide of ammonium : — 

NaBr + AgN0 3 = AgBr + NaN0 3 
10 )102.8 10 )169.7 

10.28 16.97 = 1000 c.c. of standard solution. 

Bromide of Sodium, U. S. P., should be of 97 per cent, purity, and 
the chloride may be calculated in the same manner as chloride of 
ammonium, 5.85 grammes of chloride being equal to 10.28 grammes 
of bromide of sodium. 

Cyanide of Potassium. — Operate upon from .1 to .2 gramme of 
the salt, conducting the titration as for hydrocyanic acid. The 
following reaction occurs : — 

2KCy + AgN0 3 = AgCy,KCy + KN0 3 
10)130 10 )169.7 

13 16.97 = W00 c.c. of standard solution. 

The United States Pharmacopoeia requires Cyanide of Potassium 
to contain 90 per cent, of real cyanide (KCy). 

Syrup of Hydriodic Acid. — Operate upon 10 to 15 grammes. 
The reaction which occurs is as follows : — 

HI + AgN0 3 = Agl + HN0 3 
10)1 27.6 10)169.7 

12.76 16.97 = 1000 c.c. of standard solution. 

The close of the reaction is shown by the cessation of the formation 
of iodide of silver, the nitric acid liberated rendering chromate of 
potassium inadmissible as an indicator. 

Syrupus Acidi Hydriodici, U. S. P., should contain 1 per cent. 
of anhydrous hydriodic acid (HI). 

Syrup of Bromide of Iron. — About 1 gramme should be used : — 

FeBr 2 + 2AgNO^ == 2AgBr + Fe (N0 8 ) a 
20 )215.5 20)339.4 

10.775 16.97 = 1000 c.c. of standard solution. 

It should correspond to 10 per cent, of bromide of iron (FeBr.) to 
fulfil the requirements of the United States Pharmacopoeia. 



628 VOLUMETRIC QUANTITATIVE ANALYSIS. 

Syrup of Iodide of Iron. — Operate upon 1 to 2 grammes of the 
syrup until no further precipitate is formed : — 

Fel 2 + 2AgN0 3 = 2AgI + Fe(N0 3 ) 2 
20)3 09.1 20 )339.4 

15.455 16.97 = 1000 c.c. of standard solution. 

Syrupus Ferri Iodidi, U. S. P., should contain 10 per cent, of 
iodide of iron (Fel 2 ). 

Spirit of Wine (Spiritus Rectificatus, B. P.) may contain traces 
of amylic alcohol and aldehyd ; these may be detected by nitrate of 
silver, which is reduced by them to the metallic state. Any quan- 
tity beyond a mere trace of such bodies renders spirit of wine too 
impure for use in medicine. " Four nuidounces with thirty grain- 
measures (about 2 c.c.) of the volumetric solution of nitrate of 
silver exposed for twenty-four hours to bright light, and then de- 
canted from the black powder which has formed, undergoes no 
further change when again exposed to light with more of the test." 
— B. P. " If 20 c.c. are shaken in a glass-stoppered vial, previously 
well rinsed with the same alcohol, with 2 c.c. of test-solution of 
nitrate of silver, the mixture should not be rendered more than 
faintly opalescent during one day's exposure to direct sunlight (abs. 
of more than traces of foreign organic matters, fusel oil, etc.)." — 
U.S. P. 

Iodide of Potassium may be volumetrically estimated by a semi- 
decinormal solution of mercuric chloride, the termination of the 
operation being indicated by the formation of a red precipitate : — 

(1) 4KI + HgCl 2 = 2KC1 + HgI 2 ,2KI ; 

(soluble) 

(2) HgI 2 ,2KI + HgCl 2 = 2KC1 + 2IIgI 2 . 

The author of this process, M. Personne, states that neither chlo- 
rides, * bromides, nor carbonates interfere. Carles dissolves the 
iodide in spirit of wine of 17 J per cent., as much excess of water 
decomposes the double iodide. 

Iodide of Iron.- — Messrs. Naylor and Hooper have demonstrated 
that Personnel solution is applicable to ferrous iodide, even in the 
state of syrup : — 

(1) 2FeI 2 + IIgCl 2 = FeCl 2 + FeI 2 ,HgI 2 ; 

(soluble) 

(2) FeI 2 ,HgI 2 + HgCl 2 = FeCl 2 + 2HgI 2 . 



QUESTIONS AND EXERCISES. 

1014. Explain the volumetric method of estimating the strength 
of aqueous solutions of hydrocyanic acid. 

1015. Work a sum showing how much nitrate of silver will indi- 
cate, by the official volumetric process, the presence of 1 part of real 
hydrocyanic acid. Ans. 6.2853 parts. 



ESTIMATION OF SUBSTANCES READILY OXIDIZED. 629 

ESTIMATION OF SUBSTANCES READILY OXIDIZED. 

Any deoxidizer — that is, any substance which quickly absorbs a 
definite amount of oxygen or is susceptible of any equivalent action 
— may be quantitatively tested by ascertaining how much of an 
oxidizing agent of known power must be added to a given quantity 
before complete oxidation is effected. The oxidizing agents em- 
ployed for this purpose in the United States Pharmacopoeia are 
iodine and the red chromate of potassium. Permanganate of potas- 
sium is often used for the same purpose. Iodine acts indirectly by 
taking hydrogen from water and liberating oxygen 5 the red chro- 
mate of potassium directly, by the facility with which it yields three- 
sevenths of its oxygen, as indicated by the equations and statements 
given on p. 575 ; permanganate of potassium, by affording five- 
eighths of its oxygen in presence of acid, 

2K 2 Mn 2 8 + 6H 2 S0 4 = 2K 2 S0 4 + 4MnS0 4 + 6H 2 + 50 3 . 

Standard Solution op Iodine. 
(Iodine, 1 = 126.6.) 

If pure iodine be not at hand, it may be prepared by mixing the 
commercial article with about a fourth of its weight of iodide of 
potassium and subliming. Sublimation may be effected by gently 
warming the mixture in a beaker the mouth of which is closed 
by a funnel ; the iodine vapor condenses on the funnel, while 
fixed impurities are left behind, and any chlorine which the 
iodine may contain is absorbed by the iodide of potassium, an 
equivalent quantity of iodine being liberated. Small quantities 
may be similarly treated between two watch-glasses placed edge to 
edge. Any trace of moisture in the resublimed iodine is removed 
by exposure for a few hours under a glass shade near a vessel con- 
taining oil of vitriol. 

Place 12.66 grammes of pure iodine and about 18 grammes of 
pure iodide of potassium (an aqueous solution of which is the best 
solvent of iodine ; the salt plays no other part in these operations) 
in a litre flask, add a small quantity of water, and agitate until the 
iodine is dissolved ; dilute to 1 litre. 

The following substances are officially estimated by this volu- 
metric solution : — 

Sulphurous Acid. — Operate on about .5 of a gramme of the acid, 
and dilute with water as usual. If the sulphurous acid be diluted 
to a less degree than .04 or .05 'per cent., there will be some risk of 
the sulphuric acid formed being again reduced to sulphurous acid, 
with liberation of iodine. In delicate experiments the distilled 
water used for dilution should previously be freed from air by boil- 
ing, to prevent the small amount of oxidizing action which dissolved 
air would exert. The solution of iodine is then added until a slight 
permanent brown tint is produced, showing the presence of free 
iodine. A better indicator of the termination of the reaction is 
mucilage of starch, which gives a blue color with the slightest trace 
of free iodine. 

The following equations, etc. show the reaction that takes place: — 



630 VOLUMETRIC QUANTITATIVE ANALYSIS. 

H 2 S0 3 + H 2 + I 2 = 2HI + H 2 S0 4 

20)82 20 )253.2 

4.1 1 2.66 = grms. in 1000 c.c. of standard solution. 

H 2 0,S0 2 + H 2 + I 2 = 2HI + H 2 S0 4 

20)64 ' 20 )253.2 

3.2 12.66 = grms. in 1000 c.c. of standard solution. 

The official (U. S. P.) sulphurous acid should contain 3.5 per- 
cent, of sulphurous anhydride (S0 2 ). 

Arsenic. — About .1 gramme of solid arsenic, accurately weighed, 
should be dissolved in the usual quantity of water, heated to boil- 
ing, by help of about .5 gramme of bicarbonate of sodium. The 
arsenious acid is only partly, if at all, converted into arsenite or ar- 
seniate of sodium, but the iodine reaction occurs more readily in an 
alkaline solution. When the liquid is quite cold, mucilage of starch 
is added, and the iodine solution allowed to flow in until, after well 
stirring, a permanent blue color is produced. The official solution 
of arsenite of potassium, already containing some carbonate of 
potassium, requires somewhat less. 10 grammes is a convenient 
quantity to operate upon. To this should'be added the usual quan- 
tity of water and about .3 of a gramme of bicarbonate of sodium. 
After boiling and cooling the titration is carried on as before. — 
About 10 grammes of the official solution of arsenic in dilute hydro- 
chloric acid is also a convenient quantity to operate upon. This 
quantity requires about .6 gramme of bicarbonate of sodium. The 
usual quantity of water is added, and the titration performed as be- 
fore. The following equation exhibits the reaction : — 

As 2 0, + 5H 2 + 2I 2 = 4HI + 2H 3 As0 4 




4 0)506.4 

12.66 = grms. in 1000 c.c. of standard solution. 

Arsenic, U. S. P., should contain 97 per cent., and both solutions^ 
U. S. P., contain .97 per cent, of arsenic. 

In the foregoing operation, if ebullition be continued longer than 
is necessary for the solution of the arsenic, more monocarbonate of 
sodium may be formed than will be reconverted into bicarbonate by 
the liberated carbonic acid ; loss of iodine will then ensue. E. J. 
Wooiley has shown that borax may be usefully employed in the 
place of the bicarbonate of sodium. Antimony also passes from 
lower to higher active quantivalence under the influence of nascent 
oxygen, iodine, or an equivalent acidulous radical. The following 
equation illustrates the reaction with tartar emetic and iodine. The 
student should make several determinations on, say, 20 c.c. of a solu- 
tion of 2 grammes of pure crystals of tartar emetic in 200 c.c. of 
water. To the 20 c.c. add about an equal amount of strong solution 
of bicarbonate of sodium, a couple of c.c. of starch mucilage, and 
then the iodine solution, until, after stirring, the blue color is fairly 
persistent. The whole operation should be quickly conducted or a 



ESTIMATION OF SUBSTANCES READILY OXIDIZED. 631 

precipitate of antimonious hydrate will be formed ; and it is only 
when in solution that the antimony is properly attacked. This pro- 
cess is by Mohr. It has been tested by Fresenius and in the Re- 
search Laboratory of the Pharmaceutical Society of Great Britain, 
and is trustworthy : — 

(KSbOC 4 H 4 6 ) 2 H 2 + 2F 2 + 3H 2 0=4HT + 2KHC 4 H 4 6 + 2HSb0 3 

40)664 40)5 06.4 

16.6 12.66 grammes in 100 c.c. of s. s. 

Hyposulphite of Sodium. — About .4 of a gramme is a convenient 
quantity to employ. It is dissolved in water, starch mucilage added, 
and the iodine solution slowly run in, the whole being frequently 
stirred, until a permanent blue color is produced. This is the B. P. 
process ; the U. S. P. orders a solution of sodium hyposulphite to 
be shaken with solid iodine. 

In the previous reactions iodine has acted as an indirect oxidizing 
agent by uniting with the hydrogen and thus liberating the oxygen 
of water. In the present case it unites with an analogue of hydro- 
gen — namely, sodium — a new salt (tetrathionate of sodium) being 
simultaneously produced, thus : — 

2(Na 2 S 2 3 ,5H 2 0) + I 2 = 2NaI + Na 2 S 4 6 + 10H 2 O 

2 0)496 2 0)253.2 

24.8 12.66 = grms. in 1000 c.c. of standard solution. 

The United States Pharmacopoeia requires 98 per cent, purity in 
the case of hyposulphite of sodium. 

Sulphite^ of Potassium. — About .1 gramme is a convenient quan- 
tity to take, using starch paste as an indicator, as before. The re- 
action as below occurs : — 

K 2 SQ 3 ,2H 2 + I 2 = 2KI + H 2 S0 4 + H 2 

2.0)1 9.4_ 20)2 53.2 

9.7 12.66 = 1000 c.c. of standard solution. 

Sulphite of potassium, U. S. P., should contain 90 per cent, of the 
crystallized salt (K 2 S0 3 ,2II 2 0). 

Bisulphite of Sodium. — Operate upon .05 to .07 gramme, as 
before : — 

NaIIS0 3 + I 2 + II 2 == NaT + H 2 S0 4 + HI 

2 0)104 20)253.2 

5.2 12.66 = 1000 c.c. of standard solution. 

The United States Pharmacopoeia requires bisulphite of sodium to 
contain 90 per cent, of the pure salt (NaHS0 8 ). 

Sulphite of Sodium. — -Use for this estimation about 1. to .15 
gramme, and proceed as before : — 



632 VOLUMETRIC QUANTITATIVE ANALYSIS. 

Na 2 S0 3 ,7H 2 + I 2 == 2NaI + H 2 S0 4 + 6H 2 
20 )252 20)253^2 

12.6 12.66 = 1000 c.c. of standard solution. 

This also should contain 90 per cent, of the crystallized salt to sat- 
isfy the demands of the United States Pharmacopseia. 



QUESTIONS AND EXERCISES. 

1016. Give equations illustrative of the reactions on which the 
use of a standard volumetric solution of iodine is based. 

1017. From what point of view may iodine be regarded as an 
oxidizing agent ? 

1018. What reagent indicates the termination of the reaction be- 
tween deoxidizing substances and moist iodine ? 

1019. How much sulphurous acid gas will cause the absorption of 
2.54 parts of iodine in the volumetric reaction ? Ans. .642. 

1020. What quantity of iodine will be required, under appropri- 
ate conditions, to oxidize 5 parts of arsenic? Ans. 12.008. 

1021. Find by calculation the amount of hyposulphite of sodium 
and of sulphite of sodium which will react with 13 parts of iodine 
in volumetric analysis. Ans. 25.466 and 12.9384. 



VOLUMETRIC SOLUTION OF RED CHR0MATE OF 
POTASSIUM. 

(Red Chromate of Potassium, K 2 Cr 2 7 = 294.8.) 

One molecule of red chromate of potassium in presence of an 
acid, under favorable circumstances, yields 4 atoms of oxygen to 
the hydrogen of the acid, leaving three available either for direct 
oxidation or for combination with the hydrogen of more acid, an 
equivalent proportion of acidulous radical being liberated for any 
required purpose. 

When used as a volumetric agent the red chromate always yields 
the whole of its oxygen to the hydrogen of the accompanying acid, 
a corresponding quantity of acidulous radicals being set free — four- 
sevenths of this radical immediately combining with the potassium 
and chromium of the red chromate, three-sevenths becoming avail- 
able. Ferrous may thus be converted into ferric salts with sufficient 
rapidity and exactitude to admit of the estimation of an unknown 
quantity of iron by a known quantity of the red chromate. As 1 
atom of any liberated bivalent acidulous radical will convert 2 mole- 
cules of ferrous into 1 of ferric salt, 1 molecule of red chromate 
causes 6 of ferrous to become 3 of ferric, as shown in the following 
equation : — 

K 2 Cr0 4 ,Cr0 3 + 7H 2 S0 4 + 6FeS0 4 = K 2 S0 4 ,Cr 2 3S0 4 + 7H 2 
+ 3(Fe 2 3S0 4 ). 



RED CHROMATE OF POTASSIUM. 633 

The volumetric solution is made by dissolving 14.74 grammes 
(2V of a molecular weight in grammes) of red chromate of potas- 
sium in water, and diluting to one litre. It is used in determining 
the strength of the ferrous preparations. It is known that the 
whole of the ferrous has been converted to ferric salt when a small 
drop of the liquid placed in contact with a drop of fresh and very- 
dilute solution of ferridcyanide of potassium on a white plate ceases 
to strike a blue color. 

If the red chromate employed in making this standard solution is 
not known to be pure and dry, the strength of the solution may be 
checked by dissolving a small, accurately weighed piece of piano- 
forte wire (0.4 or 0.5 gramme) in diluted sulphuric acid in a small 
flask, warming, and then running in the solution of red chromate 
until conversion is effected. 

The reactions which take place may be thus expressed : — 

6Fe + 6II 2 S0 4 = 6FeS0 4 + 6H 2 

20)335.4 20)9 11.4 

16.77 45.57 

6FeS0 4 + K 2 Cr 2 7 + 7II 2 S0 4 = 

20)91jL4_ 20)2 94.8 

45.57 14.74 = grammes in 1000 c.c. of standard solution. 

K 2 S0 4 ,Cr 2 3S0 4 + 7H 2 + 3(Fe 2 3S0 4 ) 

It is evident that 16.77 grammes of iron are equivalent in the re- 
actions to 14.74 of red chromate or 1000 c.c. of standard solution of 
the chromate. Now suppose that 0.5 of a gramme of pianoforte wire 
has been employed, and the quantity of solution of red chromate of 
unknown strength used has been 28 c.c. How many c.c. of this solu- 
tion contain 14.74 of red chromate ? that is, how many c.c. must be 
required to oxidize ferrous salt containing 16.77 of iron? As .5 of 
iron is to 28 c.c. sol., so are 16.77 of iron to x c.c. sol. = 939.12 c.c. 
Of the supposed solution, then, 939.12 c.c. would contain 14.74 
grammes of red chromate, and would be equivalent to 1000 c.c. of 
standard solution. It might be employed without being diluted, or, " 
better, be diluted to official standard strength. 

Special care should be taken in all these estimations of substances 
readily oxidized to avoid atmospheric oxidation. Flasks may usually 
be loosely corked, or corked closely with a gas exit-tube passing just 
beneath a little mercury, and in all cases the estimation should be 
performed quickly. When standardizing with iron wire any slight 
oxidation may be remedied by a fragment of zinc, the last portions 
of which must be removed or dissolved before the titration is com- 
menced. 

The ferrous salt in the following substances is estimated by this 
solution. 

Arsehiate of Iron. — Operate upon 1 to 2 grammes. Dissolve in 
excess of dilute sulphuric or hydrochloric acid. Sulphuric acid is 
preferable in most cases, because ferrous sulphate absorbs oxygen 



634 VOLUMETRIC QUANTITATIVE ANALYSIS. 

much less readily than ferrous chloride. The reaction that occurs 
is shown in the following equation, the ferrous arseniate being con- 
verted into ferric arseniate : — 

2(Fe // 3 2AsOJ + 7H 2 S0 4 + K 2 Cr 2 0- = 
20)891_ 20)294.8 

44.55 14.74 = grammes in 1000 c.c. of standard sol. 

K 2 S0 4 ,Cr 2 3SO, - Fe /// 2 3S0 4 + 2(Fe /// 2 2AsOJ -f 7H 2 

Arseniate of Iron, B. P., is supposed to contain 37.9 per cent, of fer- 
rous arseniate. The compound is more nearly a ferric than a ferrous 
arseniate. 

Phosphate of Iron. — Operate upon 1 to 2 grammes. Proceed as 
with arseniate. The following equation indicates the reaction, the 
ferrous phosphate being converted into ferric phosphate : — 



2(Fe // 3 2POJ + 7H 2 S0 4 -f K 2 Cr 2 7 = 




= 1000 c.c. of standard solution, 

K 2 S0 4 ,Cr 2 3S0 4 + Fe'" 2 3S0 4 + 2(Fe /// 2 2P0 4 ) - 7H 2 

The official (B. P.) requirement is nearly 45 per cent, of real ferrous 
phosphate. Phosphate of Iron, U. S. P., is Ferric Phosphate, and 
therefore cannot be estimated by this solution. 

Saccharated Carbonate. — Proceed as with arseniate, using about 
the same quantity : — 

6FeC0 3 + 13H 2 S0 4 + K 2 Cr 2 7 = 
20)695^4 20) 294.8 

34.77 14.74 = lOOO c.c. of standard solution. 

K 2 S0 4 Cr 2 3S0 4 4- 3(Fe 2 3SOJ + 13H 2 + 6C0 2 

The official (U. S. P.) strength is 15 per cent. Trade samples yield 
from 20 to 30, and sometimes 35, per cent., according to the care with 
which oxidation has been prevented. The theoretical percentage ob- 
tainable from the ingredients is 45.5, the quantity that would be 
present if the compounds were anhydrous and unoxidized — condi- 
tions never obtained in practice. Howie has suggested that as 
hydrochloric acid is known to so rapidly convert ordinary sugar 
into inverted sugar as to render it easily attacked by chromic acid, 
while phosphoric acid very slowly affects sugar, the latter acid in- 
stead of the former should be employed in dissolving the saccharated 
carbonate of iron for volumetric analysis. Another mode of elim- 
inating the action of sugar is to char with oil of vitriol before 
analyzing. 

Magnetic Oxide of Iron. — Use about the same quantity, and pro- 
ceed as with arseniate or phosphate. The reaction may thus be 
shown :— 



RED CHROMATE OF POTASSIUM. 635 

6Fe 3 4 + 31H 2 S0 4 + K 2 Cr 2 7 = 




= grammes in 1000 c.c. of standard solution. 

K 2 S0 4 ,Cr 2 3S0 4 + 9(Fe 2 3S0 4 ) + 31H 2 
or, 
6(Fe 2 3 ,FeO) + 31H 2 S0 4 + K 2 Cr 2 7 = 

20)431.4 20)294,8 

21 .57 14.74 = grammes in 1000 c.c. of stand, solution. 

K 2 S0 4 ,Cr 2 3S0 4 + 9(Fe 2 3S0 4 ) + 31H 2 

Absolutely pure magnetic oxide of iron contains 31 per cent, of 
ferrous oxide. Oxidation occurs, however, during manufacture, as 
in the case of the ferrous salts just described. The British Pharma- 
copoeia recognizes magnetic oxide containing nearly 25 per cent, of 
ferrous oxide. 

Sulphate of Iron. — Operate upon about 1 gramme of the crystal- 
lized or precipitated salt in presence of excess of sulphuric acid ; 
the reaction which occurs has been already given when treating 
of the standardizing of solution of Bichromate of Potassium on 
page 575. 

The United States Pharmacopoeia demands almost absolute 
purity for both Ferri Sulphas and Ferri Sulphas Precipitatus 
(FeS0 4 ,7H 2 0). 

Note. — The use of this volumetric solution in quantitative analy- 
sis admits of great extension. The student should at least employ 
it in the case of a few iron ores. 



QUESTIONS AND EXERCISES. 

1022. Write equations explanatory of the oxidizing power of red 
chromate of potassium. 

1023. One hundred cubic centimetres of an aqueous solution of 
red chromate of potassium contain 2^0 °f ^he molecular weight of 
the salt in grammes ; with what weight of metallic iron, dissolved 
in hydrochloric acid, will this volume react? Ans. 1.677 grammes. 

1024. If 8.34 grammes of impure crystallized ferrous sulphate, 
dissolved in acidulated water, require 93 c.c. of the standard solution 
of chromate for complete conversion into ferric salt, what percentage 
of ferrous sulphate is present? Ans. 92.966. 

1025. Work a sum showing how much red chromate of potassium 
is required for the conversion of 10 parts of ferrous sulphate into 
ferric salt. A71S. 1.768. 

1026. Show what quantity of pure ferrous carbonate is indicated 
by I.475 parts of red chromate as applied in volumetric analysis. 
Ans. 3.479. 

1027. Prove what amount of official saccharated carbonate of 
iron is equivalent to .7375 part of red chromate in the volumetric 
reaction. Ans. 11.598. 



636 VOLUMETRIC QUANTITATIVE ANALYSIS. 

ESTIMATION OF SUBSTANCES READILY DEOXIDIZED. 

Any substance which quickly yields a definite amount of oxygen 
may be quantitatively tested by ascertaining how much of a deoxi- 
dizing agent of known power must be added to a given quantity 
before complete deoxidation is effected. The chief compounds which 
may be used for this absorption of oxygen (deoxidizers or reducing 
agents, as they are commonly termed) are hyposulphite of sodium, 
sulphurous acid, ferrous sulphate,* oxalic acid, arsenious acid. The 
first named is officially employed ; it is only used in the estimation 
of free iodine, and, indirectly, of chlorine and chlorinated compounds. 
Iodine and chlorine are regarded as oxidizing agents, because their 
great affinity for Irydrogen enables them to become powerful indirect 
oxidizers in presence of water. 

Standard Solution of Hyposulphite of Sodium. 
(Crystallized Hyposulphite of Sodium. Na 2 S 2 3 ,5H 2 = 248.) 
Dissolve about 27 grammes of hyposulphite of sodium in a litre 
or less of water. Fill a burette with this solution, and allow it to 
flow into a beaker containing, say, 15 c.c. of the volumetric solution 
of iodine until the brown color of the iodine is just discharged, or, 
starch being added, until the blue iodide of starch is decolorized. 
(The latter affords the more delicate indication.) AVhen iodine and 
hyposulphite of sodium react, 2 atoms of iodine remove 2 of sodium 
from 2 molecules of the hyposulphite, tetrathionate of sodium being 
formed, as indicated in the following equation : — 

I 2 + 2(Xa 2 S 2 Q 3 ,5H 2 Q) ^ 

20)253.2 20)496_ 

12.66 = grais. of iodine in 1000 c.c. 24.8 = grms. of hypo, in 1000 c.c. 

2XaI — Xa 2 S,0 6 + 10H 2 O 

Now, suppose the number of c.c. required to deoxidize the 15 c.c. 
of standard iodine were 14 cc, how man} 7 c.c. of this hyposulphite 
solution would be equivalent to 1000 c.c. of standard iodine solution ? 
In other words, how many c.c. would contain 24.8 grammes of hypo- 
sulphite? As 15 c.c. iodine sol. are to 14 c.c. hyposulph. sol., so 
are 1000 iodine sol. to x hyposulph. sol. = 933 c.c. Therefore, 933 
c.c. of this solution of hyposulphite would contain 24.8 grammes 
of the salt, and be equivalent to 1000 c.c. of the official standard 
solution. The 933 c.c. would be diluted to 1000 c.c, or be used 
without dilution. In either case its strength would, as usual, be 
recorded on the label. The following substances are estimated 
officially by means of this solution. 

Chlorine- Water. — About 10 grammes are operated upon. Excess 
of iodide of potassium is added ; that is, to 10 grammes of solution 

* Five grains of permanganate of potassium dissolved in water re- 
quire for decoloration a solution of forty-four grains of granulated sul- 
phate of iron acidulated with two fluidrachms of diluted sulphuric 
acid. 



VOLUMETRIC ESTIMATION OF OXIDIZERS. 637 

of chlorine about half a gramme of iodide. An amount of iodine 
is set free by the chlorine exactly in proportion to their atomic 
weights. The titration is then conducted as already described. 
The following shows the reaction : — 

Cl 2 + 2KI = I 2 + 2KC1 

20yn 2 0)253.2 

3.55 12.66 

I 2 + 2(Na 2 S 2 3 ,5H 2 0) = 2NaI + Na 2 S 4 6 + 10H 2 O 



20 )253.2 20)496 

12.66 24.8 = grammes in 1000 c.c. of standard solution. 

It is evident, then, that 1000 c.c. of standard solution of hypo- 
sulphite of sodium, or a corresponding quantity of a solution of 
different strength, is equivalent to 3.55 grammes of chlorine gas. 
Chlorine-Water of the United States Pharmacopoeia contains .4 per 
cent, of chlorine gas. 

Iodine. — Solid iodine is dissolved in solution of iodide of potas- 
sium, and titrated as already described. About .2 of a gramme is a 
convenient quantity to employ. 1000 c.c. of standard hyposulphite 
solution are equivalent, as seen in the equation, to 12.66 of iodine. 
The United States Pharmacopoeia requires "iodine" to contain 100 
per cent, of real iodine. It is assumed in this operation that the 
iodine has been shown by qualitative analysis to be free from chlo- 
rine and bromine. These elements resemble iodine in reacting 
upon hyposulphite of sodium, hence would reckon as iodine in a 
volumetric assay. 

Chlorinated Lime. — Operate on from .1 to .2 of a gramme. Dis- 
solve in the usual quantity of water, and add excess either of dilute 
hydrochloric or dilute sulphuric acid and of iodide of potassium : 
.1 to .2 of a gramme of chlorinated lime would require .4 to .8 of a 
gramme of iodide of potassium. The following equations show the 
reactions : — 

CaOCl 2 + 2HC1 = CaCl 2 + H 2 + Cl 2 ; 
or, 

CaOCl 2 + H 2 S0 4 = CaSO, + H 2 + Cl 2 . 

The chlorine thus set free liberates an equivalent amount of iodine, 
and this is titrated as before. (See the equations for solution of 
chlorine.) This chlorine, liberated from chlorinated lime by acids, 
is its available chlorine for indirect oxidizing action. It should 
correspond (U. S. P.) to 25 per cent. 

Solution of Chlorinated Lime. — About 2 grammes is a convenient 
quantity to operate upon. 1 gramme of iodide of potassium and 
excess of acid should be added, and the available chlorine deter- 
mined as in the case of the solid. The official (U. S. P.) require- 
ment is 2.9 per cent, of available chlorine. 

Solution of Chlorinated Soda. — About 2 grammes are mixed w ith 
the usual quantity of water, excess of acid added, and about 1 



638 VOLUMETRIC QUANTITATIVE ANALYSIS. 

gramme of iodide of potassium. The available chlorine is esti- 
mated as in the case of chlorinated lime. The reaction by which 
the chlorine is evolved is similar : — 

.NaCl,NaOCl + 2HC1 = 2NaCl + H 2 + Cl 2 . 

The action of the liberated chlorine on the iodide of potassium 
and the iodine on the hyposulphite solution has been given under 
" Solution of Chlorine." The official (U. S. P.) requirement is 2 
per cent, of available chlorine. 

Compound Solution of Iodine. — Process as before, using 1 or 2 
grammes ; the reaction has already been given. The requirements 
of the United States Pharmacopoeia are 5 per cent, of free iodine. 

Tincture of Iodine. — Use about 1 gramme. It will contain 8 per 
cent, of free iodine when of official strength. 



QUESTIONS AND EXERCISES. 

1028. For what purposes is the official volumetric solution of 
hyposulphite of sodium used ? 

1029. On what reaction is based the quantitative employment of 
hyposulphite of sodium? 

1030. How much hyposulphite of sodium is required to show the 
presence of 10 parts of iodine ? Ans. 19.527. 

1031. To what amount of chlorine is 4.96 parts of hyposulphite 
of sodium equivalent in volumetric analysis? Ans. 0.71. 

1032. Describe the operation included in the estimation of the 
strength of bleaching-powder. 

1033. By what reagent is the complete absorption of free iodine 
by hyposulphite of sodium indicated ? 

MISCELLANEOUS PROBLEMS. 

1034. Work sums showing how much bicarbonate of potassium is 
contained in an eight-ounce bottle of medicine, seven fluiddrachms of 
which are saturated by two and a half grains of crystallized oxalic 
acid. Ans. 36.3 grains. 

1035. A sample of soda-ash is said to contain 78 per cent, of pure 
anhydrous carbonate of sodium ; if the statement is true, how much 
of the official volumetric solution of oxalic acid will saturate 5 
grammes of the specimen ? Ans. 73.6. 

1036. 2.69 grammes of common brown sulphuric acid are satu- 
rated by 43.5 cubic centimetres of the official volumetric solution of 
soda ; how much acid of 96.8 per cent, is present ? Ans. The 2.69 
contained 2.2. 

1037. Four grammes of a litre and a half of concentrated hydro- 
cyanic acid are neutralized by 89 cubic centimetres of volumetric 
solution of nitrate of silver of official strength by the official process ; 
to what volume must the bulk of the acid be diluted for the produc- 
tion of acid of pharmacopceial strength ? Ans. 4j litres. 

1038. 3.18 grammes of a powder containing arsenic require for 



ESTIMATION OF POTASSIUM. 639 

complete reaction 84 cubic centimetres of a volumetric solution of 
iodine, which is 1.43 per cent, weaker than the standard solution of 
the United States Pharmacopoeia ; what percentage of pure arsenic 
is contained in the powder? Ans. 12.863. 

1039. How much pure metal is present in a sample of iron 1.68 
of a gramme of which, dissolved in dilute sulphuric acid, is exactly 
attacked by 95.7 cubic centimetres of semi-decinormal volumetric 
solution of red chromate of potassium which is 6 per cent, too 
strong ? 

GRAVIMETRIC QUANTITATIVE ANALYSIS. 

ESTIMATION OF METALS. 

POTASSIUM. 

Outline of the Process. — This element is usually estimated in the 
form of double chloride of potassium and platinum. Qualitative 
analysis having proved the presence of potassium and other radi- 
cals in a substance, a small quantity of the material is accurately 
weighed, dissolved, and the other elements removed by appropriate 
reagents 5 the precipitates are well washed, in order that no trace 
of the potassium salt shall be lost, the resulting liquid concentrated 
over a water-bath (to avoid loss that would occur mechanically 
during ebullition), hydrocholoric acid added if necessary, solution of 
perchloride of platinum poured in, and evaporation continued to 
dryness 5 excess of the perchloride is then dissolved out by adding 
to the dried residue spirit of wine containing half its bulk of ether 
(a liquid in which the double chloride is insoluble), the mixture 
carefully poured on to a tared and dried filter, washed with the spirit 
till every trace of free perchloride of platinum is removed, the whole 
dried and weighed 5 from the resulting amount the proportion of 
potassium, or equivalent quantity of a salt of potassium, is ascer- 
tained by calculation. 

Note. — From this short description it will be seen, first, that the 
chemistry of quantitative is the same as that of qualitative analysis ; 
second, that the principle of gravimetric is the same as that of 
volumetric quantitative analysis : the combining proportions being 
known, unknown quantities of elements may be ascertained by 
calculation from known quantities of their compounds. 

Apparatus. — In addition to a delicate balance and weights 
and the common utensils, a few special instruments are used in 
quantitative manipulation ; some of these may be prepared 
before proceeding with the estimation of potassium. 

Filtering-paper may be of the kind known as' ".Swedish," 
the texture of which is of the requsite degree of closeness 
and its ash small in amount. A large number of circular pieces 
of one size, six to eight centimetres in diameter, should be cut 
ready for use. In delicate experiments, where a precipitate on 
a filter has to be ignited and the paper consequently burnt, the 



640 



GRAVIMETRIC QUANTITATIVE ANALYSIS. 



weight of the ash of the filter must be deducted from the weight 
of the residue. The ash is estimated after burning ten or 
twenty of the cut filters. These are folded into a small com- 
pass, a portion of a piece of platinum wire twisted a few times 
round the packet, so as to form a cage, the whole held by the 
free end of the wire over a weighed porcelain crucible placed 
in the centre of a sheet of glazed paper, the bundle ignited by 
a spirit-lamp or smokeless gas-flame, the flame allowed to im- 
pinge against the charred mass till it falls into the crucible 
below, any stray fragments on the sheet carefully shaken into 
the crucible, the latter placed over a flame till carbon has all 
burnt off and nothing but ash remains, the whole cooled, 
weighed, and the weight of the crucible deducted ; the weight 
of the residue divided by the number of pieces used gives the 
average amount of ash in each filter. 

A pair of weighing-tubes (Fig. 75), for holding dried filters 
during operations at the balance, may be made from two test- 
tubes, one fitting closely within the other. About five cen- 
timetres of the closed end of the outer and seven of the 
inner are cut off by leading a crack round the tube with a 



Fig. 75. 



Fig. 76. 



A pair of weighing-tubes. 



Clamped watch-glass for weighing. 



pencil of incandescent charcoal, and the sharp edges fused in 
the blowpipe-flame. A filter, after drying, is quickly folded 
and placed in the narrower tube, the mouth of which is then 
closed by the wider tube. This prevents reabsorption of moist- 
ure from the air. 

A pair of watch-glasses, having accurately ground edges 
and clamped, as shown in Fig. 76, also form 
Fig. 77. a convenient arrangement for weighing fil- 

ters, etc. 

The washing-bottle, holding the spirit of 
wine and ether, is a common flask through 
the cork of which a short straight tube passes. 
The outer end of the tube should be suffi- 
ciently narrowed to enable it to deliver a 
very fine stream of the liquid. The flask 
being inverted, the warmth of the hand ex- 
The washing-bottle, pands the air and vapor to a sufficient extent 
to force out the liquid. 




ESTIMATION OF POTASSIUM. 641 

The ordinary washing-bottle for quantitative operations should 
be formed of a flask in which water may be boiled, fitted up as 
usual (vide p. 108). 

A water-oven is the best form of drying-apparatus. It is a small 
square copper vessel, jacketed on five sides and having a door on the 
sixth ; water is poured into the space between J^he inner and outer 
casing, and the whole placed over a gas-lamp or source of heat, 
moist air and steam escaping by appropriate apertures. Desiccation 
at higher temperatures than the boiling-point of water may be prac- 
tised by using oil or paraffin instead of water, inserting a ther- 
mometer in the fat. The apparatus may be purchased of any maker 
of chemical instruments. 

Pure distilled water must be used in all quantitative determina- 
tions. 

Note. — In practising the operations of quantitative analysis, ex- 
periments should at first be conducted on definite salts of known 
composition, for the accuracy of results may then be tested by 
calculation. 

Estimation of Potassium in the Form of Double Chloride of 
Potassium and Platinum. — Select two or three crystals of pure 
nitrate of potassium, powder them in a clean mortar, dry the 
powder by gently heating in a porcelain crucible over a flame 
for a few seconds, place about a couple of decigrammes (0.2 
grm.) of the powder in a counterpoised watch-glass, accurately 
weigh the selected quantity, transfer to a small dish, letting 
water from a wash-bottle flow over the watch-glass and run 
into the dish, warm the dish till the nitrate is dissolved, acid- 
ulate with hydrochloric acid, add excess of aqueous solution of 
perchloride of platinum (a quantity containing about 0.4 of 
solid salt), evaporate to dryness over a water-bath. While 
evaporation is going on place a filter and the weighing-tubes 
in the water-oven, exposing them to a temperature of 100° C. 
for about half an hour ; fold the filter and insert it in the tubes, 
place them on a plate under a glass shade, and when cold 
accurately note their weight. Arrange the weighed filter in a 
funnel over a beaker. Transfer the dried and cooled platinum 
salt from the dish to the filter by moistening the residue with 
the mixture of alcohol and ether, and when the salt is loosened 
pouring the contents of the dish into the paper cone. Any 
salt still adhering may be freed by the finger, which, together 
with the dish, should be washed in the stream of spirit, the 
rinsings at once flowing into the filter. The filtrate should 
have a yellowish-brown color, due to the excess of perchloride 
of platinum. If it is colorless, an insufficient amount of per- 
chloride has been added, and the whole operation must be 
repeated. The washed precipitate and filter are finally dried 
54* 



642 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

in the water-oven, folded and placed in the weighing-tubes, the 
drying continued until the whole, after repeated weighing when 
cold, ceases to alter ; the final weight is noted. 

Note. — If filters are not freed from all trace of acid by thorough 
washing, the paper wUl be brittle when dry, falling to pieces on being 
folded. 

Analytical memoranda in the note-book may have the fol- 
lowing form : — 

Watch-glass and substance . . 

Watch-glass 

Substance . 

Weighing tubes, filter, and Pt salt 
Weighing tubes and filter . . . 
PtCl 4 ,2KCl 
The calculations are simple : — 

As \ _ £k . r> [■ are equivalent io -j ^_ ono 3 r > 

f the weight of ^ 
so I double chloride > is equivalent to x. x will be the amount 
( obtained j 

of pure nitrate of potassium in the quantity of substance ope- 
rated on. x should, in the present instance, be identical with 
the weight of substance taken, because, for educational pur- 
poses, pure nitre is under examination. Only after analyses of 
pure substances have yielded the operator results identical with 
those by calculation can analyses of substances of unknown 
degree of purity be undertaken with confidence. A Table of 
Atomic Weights, from which to find molecular weights, is given 
in the Appendix. 

Platinum residues should be preserved, and the metal recovered 
from them from time to time (vide p. 245). 

Hot alcohol sometimes reduces perchloride of platinum, the metal 
being thrown out of solution in a finely-divided form known as plati- 
num black ; only aqueous solutions, therefore, of the salt should be 
used where heat is employed. Hence, also, in washing out excess of 
perchloride of platinum from the double chloride of platinum and 
potassium by spirit the application of heat should be avoided. 

Effervescing Potash-ivater (Liquor Potassce Fffervescens, B. P.) 
is most easily estimated volumetrically (p. 561). Any adulteration 
by an equivalent amount of bicarbonate of sodium would, however, 
by that process be undetected ; hence the Pharmacopoeia directs that 



ESTIMATION OF POTASSIUM. 



643 



"5 fluidounces, evaporated to one-fifth, and 12 grains of tartaric 
acid added, yield a crystalline precipitate which, when dried, weighs 
not less than 12 grains." Five fluidounces of this preparation should 
contain 7.5 grains of bicarbonate, convertible into 14.1 grains of acid 
tartrate of potassium by 11.25 grains of tartaric acid. The method 
is somewhat rough, but quite efficient for " potash-water" containing 
nothing but bicarbonates of alkali-metals. 

Proportional Weights of Equivalent Quantities of Potassium 
and its Salts. 



Metal 

Oxide (" potash ") . 
Hydrate (" caustic potash ") 
Carbonate (anhydrous) 
Carbonate (crystalline) 



K 2 ..... . 78 

K 2 94 

2KHO 112 

K 2 C0 3 138 

K 2 C0 3 + 16 % aq. . 164.285 



Bicarbonate 2KHC0 3 . . . . 200 

Nitrate 2KN0 3 202 

Platinum salt ..... PtCL2KCl . . . 484.8 



SODIUM. 

Sodium is usually estimated as sulphate. Accurately weigh 
a porcelain crucible and lid, place within about .3 grm. of pure 
rock-salt, and again weigh, making a memorandum of the weights 
in a note-book. Add rather more strong sulphuric acid than 
may be considered sufficient to convert the chloride into acid 
sulphate "of sodium. Heat the crucible gradually, the flame 
being first directed against the side of the crucible to avoid 
violent ebullition, until fumes of acid cease to be evolved, 
toward the end of the operation dropping in one or two frag- 
ments of carbonate of ammonium to facilitate complete expul- 
sion of all excess of acid. When cold, weigh the crucible and 
contents. The weight of the crucible having been deducted, 
the amount of sulphate obtained should be the exact equivalent 
of the quantity of chloride of sodium employed. 

2NaCl + H 2 SO, = Na 2 SO, + 2HC1. 



117 



142 



Proportional Weights of Equivalent Quantities of Sodium and 
its Salts. 



Metal 

Oxide (" soda ") . . . 
Hydrate (" caustic soda ") 
Carbonate (anhydrous) . 
Carbonate (crystals) . . 



Na, . 
Na 2 . 
2NaHO 

Na.,CO, 
Na 2 CO„10II 



,0 



46 

(52 

80 

106 

286 



644 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

Bicarbonate 2NaHC0 3 . . . 168 

Chloride 2NaCl .... 116.8 

Sulphate (anhydrous) . . . ' . Na 2 S0 4 .... 142 

Sulphate (crystals) Na 2 SO 4 ,10H 2 O . . 322 

AMMONIUM. 

Salts of ammonium are, for purposes of quantitative analysis, 
generally converted into the double chloride of ammonium and 
platinum (PtCl 4 ,2NH 4 Cl), the details of manipulation being the 
same as those observed in the case of potassium. About 0.15 
grm. of pure, white, dry chloride of ammonium may be taken 
for experiment. 

Composition of the Platinum Salt. 



Pt . . 

Cl 6 . . 
N 2 . . 
H 8 . . 


. 194.4 

35.4 X 6 . 
14.0 X 2 . 

1.0X8 . 

. 336 

. 53.4 X 2 . 


In 1 molec. wt. 

. . 194.4 . 
. . 212.4 . 
. . 28 
. . 8 
442.8 

In 1 molec. wt. 

. . 336 
. . 106.8 . 
442.8 


In 100 parts. 
. . 43.903 

. . 47.967 
. . 6.324 
. . 1.806 


or, PtC! 4 . 
2NH 4 C1 


100.000 

In 100 parts- 

. . 75.88 

. . 24.12 

100.00 



The proportion of nitrogen, ammonium, or chloride of am- 
monium in the double chloride may also be ascertained from 
the weight of platinum left on igniting the double chloride ; 
indeed, this operation must be performed if any variety of am- 
monium other than the ordinary hydrogen ammonium may be 
present. The heat must be applied slowly, or platinum will be 
mechanically carried off with the gaseous products of decom- 
position. 

Proportional Weights of Equivalent Quantities of Ammoniacal 
Compounds. 

Ammonia (gas) 2NH 3 .... 34 

Ammonium (NH 4 ) 2 ? . . . . 36 

Chloride of ammonium .... 2NH 4 C1 . . . . 106.8 

Platinum salt PtCl 4 ,2NH 4 CI . . 442.8 

" Carbonate of ammonium " . . (N 4 H 16 C 3 8 ) -*- 2 . 118 

Sulphate of ammonium .... (NH 4 ) 2 S0 4 . ; . 132 

BARIUM. 

Barium is estimated in the form of anhydrous sulphate of 
barium (BaS0 4 ). 



ESTIMATION OF BARIUM. 645 

Process. — Dissolve 0.3 or 0.4 grm. of pure crystallized and dried 
chloride or nitrate of barium in about half a litre of water in a 
beaker, heating to incipient ebullition, and slightly acidulating 
with hydrochloric or nitric acid. Add diluted sulphuric acid 
(prepared some days previously, so that sulphate of lead may 
have deposited) so long as a precipitate forms ; keep the mix- 
ture hot for some time, set aside for half an hour, pass the 
supernatant liquid through a filter, gently boil the residue two 
or three times with more water; finally, collect the precipitate 
on the filter, removing adherent particles from the beaker by 
the finger and cleansing by a stream of hot water from the 
wash-bottle. The precipitate must be washed with hot water 
until the filtrate ceases to turn litmus-paper red or give any 
cloudiness when tested with chloride of barium. The filter and 
sulphate of barium, having thoroughly drained, are dried in a 
warm place, commonly by supporting the funnel in an inverted 
bottomless beaker over a sand-bath or hot plate. 
. The sulphate of barium is now removed from the filter, 
heated to drive off every trace of moisture, and weighed. This 
is accomplished by placing a weighed porcelain crucible (and 
cover) on a sheet of glazed paper, holding the filter over it, 
and carefully transferring the precipitate ; the sides of the 
filter are then gently rubbed together and detached powder 
dropped into the crucible, the paper folded, encased in two or 
three coils of one end of a platinum wire and burnt over the 
crucible, ash and any particles in the sheet of paper dropped 
into the sulphate of barium, the open crucible exposed over a 
flame till its contents are quite white, covered, cooled, and 
weighed. 

Formula*. Molecular 

weights. 

Chloride of barium .... BaCl 2 ,2H 2 . 243.(3 
Nitrate of barium .... Ba2N0 3 . 260.8 

Sulphate of barium . . . BaS0 4 . 232.8 

Composition of Sulphate of Barium. 

Ba 130.8. . 

S 32 . . 

4 ..... 16X4. 

In these educational experiments it is unnecessary to take 
filter-ash into account. Inevitable mistakes of manipulation 
by students commonly cause far greater errors. 



Inl 
molec. wt. 

130.8 


Tn 100 
parts. 

. 5S.TT 


32 . 


. 13.73 


64 . 


. 27.50 


532.8 


100.01) 



646 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

CALCIUM. 

Calcium is usually thrown out of solution in the form of oxa- 
late, the precipitate ignited, and the resulting carbonate weighed. 

Process. — Dissolve 0.3 grm. or 0.4 of dried colorless crystals 
of calc-spar in about a third of a litre of water acidulated with 
hydrochloric acid, heat the solution to near the boiling-point, 
add excess of solution of oxalate of ammonium, then ammonia, 
until, after stirring, the liquid smells strongly ammoniacal ; set 
aside in a warm place for twelve hours. Carefully pour off 
the supernatant liquid, passing it through a filter; add hot 
water to the precipitate, set aside for half an hour, again 
decant, and after once more washing transfer the precipitate to 
the filter, allowing all contained fluid to pass through before a 
fresh portion is added. Wash the precipitate with hot water, 
avoiding a rapid stream or the precipitate may be driven 
through the pores of the paper. Dry, transfer to a weighed 
crucible, and incinerate, as described for sulphate of barium, 
and slowly heat the precipitate till the bottom of the crucible 
is just visibly red when seen in the dark. As soon as the 
residue is white or only faintly gray remove the lamp, cool, 
and weigh. 

The resulting carbonate of calcium should have the same 
weight as the calc-spar from which it was obtained. If loss 
has occurred, carbonic acid gas has probably escaped. In 
that case moisten the residue with water, and after a few 
minutes test the liquid with red litmus- or turmeric-paper ; if 
an alkaline reaction is noticed, it is due to the presence of 
caustic lime. Add a small lump of carbonate of ammonium, 
evaporate to dryness over a water-bath, and again ignite, this 
time being careful not to go beyond the prescribed temperature. 
The treatment may, if necessary be repeated. 

Proportional Weights of Equivalent Quantities of Calcium 
Salts. 

Oxide (quicklime) CaO 56 

Hydrate (slaked lime) .... Ca2HO . . . . 74 

Carbonate CaC0 3 .... 100 

Sulphate (anhydrous) CaS0 4 .... 136 

Sulphate (crystalline or precipitated) CaS0 4 ,2H 2 . . 172 

Chloride CaCl 2 .... 110.8 

Phosphate (of bone) (Ca 3 2PO 4 )310 ■+■ 3 103.3 

Superphosphate CaH 4 2PO, ... 234 



ESTIMATION OF MAGNESIUM. 647 

MAGNESIUM. 

Process 1. — The light or heavy carbonate of magnesium of 
pharmacy may be estimated by heating a weighed quantity to 
redness in a porcelain crucible. If it has the composition 
indicated by the formula given in the British Pharmacopoeia 
(3Mg0O 3 ,Mg2HO,4H 2 O), it will yield 42 per cent, of mag- 
nesia (MgO). According to that work, the purity of even 
sulphate of magnesium (MgS0 4 ,'7H 2 0) may be determined by 
boiling a weighed quantity with excess of carbonate of sodium, 
collecting the precipitate, washing, drying, igniting, and weigh- 
ing the resulting magnesia (MgO). The crystalline sulphate 
should afford 16.26 per cent, of oxide. The official solution of 
carbonate of magnesium in carbonic acid water (Liquor Mag- 
nesise Carbonatis, B. P.) should yield five grains of pure oxide 
of magnesium per fluidounce. 

Process 2. — The general form in which magnesium is precip- 
itated is as phosphate of ammonium and magnesium (MgN 
H 4 P0 4 ,6H 2 0) ; this, by heat, is converted into pyrophosphate 
of magnesium (Mg 2 P 2 7 ). Accurately weigh a small quantity 
(0.4 to 0.5 grm.) of pure dry crystals of sulphate of magne- 
sium, dissolve in two or three hundred cubic centimetres of cold 
water in a beaker, add chloride of ammonium, ammonia, and 
phosphate of sodium or ammonium, agitate with a glass rod 
(without touching the sides of the vessel, or crystals will firmly 
adhere to the rubbed portions), and set aside for twelve hours. 
Collect orr a filter, wash the precipitate with water containing 
a tenth of its volume of the strongest solution of ammonia, 
until the filtrate ceases to give a precipitate with an acidulated 
solution of nitrate of silver. Dry, transfer to a crucible, burn 
the filter in the usual way, heat slowly to redness, cool, and 
weigh. 

Proportional Weights of Equivalent Quantities of Magnesium 
Salts. 

Pyrophosphate . . Mg 2 P 2 7 222 

Sulphate .... 2(MgS0 4 ,7H a O) 492 

Oxide 2(MgO) 80 

Official carbonate . (3MgC0 3 ,Mg2HO ; 4II 2 0)-f-2 . . 191 

ZINC. 

Zinc is usually estimated as oxide (ZnO), occasionally as 
sulphide (ZnS). Zn = 64.0. 

Process. — Dissolve a weighed quantity (0.5 to 0.6 grm.) of sul- 



648 



GRAVIMETRIC QUANTITATIVE ANALYSIS. 



pliate of zinc in about half a litre of water in a beaker, heat to 
near the boiling-point, add carbonate of sodium in slight excess, 
boil, set aside for a short time ; pass the supernatant liquid 
through a filter, gently boil the precipitate with more water, 
again decant ; repeat these operations two or three times ; col- 
lect the precipitate on the filter, wash, dry, transfer to a 
crucible, incinerate, ignite, cool, and weigh. 286.9 (= molec. 
weight) of sulphate should yield 80.9 (= molec. weight) of 
oxide. 

MANGANESE. 

To ascertain its value for evolving chlorine from hydrochloric 
acid a weighed quantity of finely-powdered black oxide of 
manganese is heated in a small flask with pure hydrochloric 
acid, and the resulting chlorine conveyed into a U-tube con- 
taining solution of iodide of potassium. The amount of iodine 
thus freed is estimated by the volumetric solution of hypo- 
sulphite of sodium. 126.6 of iodine indicate 35.4 of chlorine. 
Manganese may also be estimated by the reaction and apparatus 
described under " Oxalates," page 665. (See Fig. *78). 



Fig. 78. 




ALUMINIUM. 

Aluminium is always precipitated as hydrate (Al 2 6HO) and 
weighed as oxide (A1 2 3 ). 

Process. — Dissolve about 2 grammes of pure dry ammonium 
alum in half a litre of water, heat the solution, add chloride 
of ammonium and a slight excess of ammonia, boil gently till 
the odor of ammonia has nearly disappeared, set aside for the 
hydrate to deposit, pass the supernatant liquid through a filter, 
wash the precipitate three or four times by decantation, trans- 
fer to the filter, finish the washing, dry, burn the filter, ignite 
in a covered crucible, and weigh. 



ESTIMATION OF ALUMINIUM. 649 

A1 2 3S0 4 K 2 S0 4 ,24H 2 948 

A1 2 3S0 4 ,(NH 4 ) 2 S0 4 ,24H 2 906 

A1 2 3 102 

Per cent, of A1 2 3 yielded by ammonium alum . . 11.26 



QUESTIONS AND EXERCISES. 

1040. Give details of the manipulations observed in gravimetric- 
ally estimating salts of potassium or ammonium. 

1041. What quantity of chloride of sodium is contained in a sam- 
ple of rock-salt 0.351 gramme of which yields 0.426 of sulphate of 
sodium? Ans. 99.83 per cent. 

1042. To what amount of the ammonium alum is 10.888 of a 
gramme of the double chloride of platinum and ammonium equiva- 
lent? Ans. 1.817 grammes. 

1043. Find the weight of sulphate of barium obtainable from 
0.522 of nitrate. Ans. 0.466. 

1044. Describe the usual method by which salts of calcium are 
estimated. 

1045. By what quantitative processes may the official salts of 
magnesium be analyzed ? 

1046. Calculate the proportion of pure sulphate of zinc in a sam- 
ple of crystals 0.574 of which yield 0.161 of oxide. Ans. 99.46 per 
cent. 

1047. Ascertain the weight of alumina (A1 2 3 ) which should be 
obtained from 1.812 grammes of ammonium alum. 



IRON. 

Iron and its salt are gravimetrically estimated in the form 
of ferric oxide (Fe 2 Q 3 ). 

Compounds containing organic acidulous radicah are simply 
incinerated, and the resulting oxide weighed. Thus, 1 gramme 
of the official citrate of iron and ammonium (Ferri ct Ammom'se 
Citras, B. P.), incinerated, with exposure to air, leaves not 
less than .27. of ferric oxide. A small quantity of the salt is 
weighed in a tared covered porcelain crucible, flame cautiously 
applied until vapors cease to be evolved, the lid then removed, 
the crucible slightly inclined and exposed to a red heat until 
all carbonaceous matter has disappeared. The residual ferric 
oxide is then weighed. The tartrate of potassium and iron 
(Ferrum TaHaratum ) 1>. P.) is treated in the same manner, 
except that the ash must be washed and again heated before 
weighing, in order to remove carbonate" of potassium produced 
during incineration : 5 grammes should yield 1.5 grammes of 
ferric oxide. 

55 



650 



GRAVIMETRIC QUANTITATIVE ANALYSIS. 



From other compounds of iron, soluble in water or acid, the 
metal is precipitated in the form of hydrate (Fe 2 6HO) by solu- 
tion of ammonia, and converted into oxide (Fe 2 60 3 ) by ignition. 
Dissolve a piece (about 0.2 grm.) of the purest iron obtainable 
(piano wire), accurately weighed, in water acidulated with 
hydrochloric acid ; add a few drops of nitric acid and gently 
boil ; pour in excess of ammonia, stir, set aside till the ferric 
hydrate has deposited, pass the supernatant liquid through a 
filter, treat the precipitate three or four times with boiling 
water ; transfer to the filter, wash till the filtrate yields no 
trace of chlorine (for chloride of ammonium will decompose 
ignited ferric oxide, with volatilization of ferric chloride), dry 
and ignite as usual, and weigh. Iron in the official solutions 
(Liquor Ferri Perchloridi Fortior, Liquor Ferri JVitratis, and 
Liquor Ferri Tersuljphatis) may be estimated by this general 
process. 

The proportion of metallic iron in a mixture of iron and ox- 
ides of iron may be determined by digestion in a strong solu- 
tion of iodine in iodide of potassium, which attacks the metal . 
only. The reduced iron of pharmacy (Ferrum Redaction) is 
in good condition so long as it contains, as shown by this 
method, half its weight of free metal. 

Another Method. — Reduced iron is converted into ferrous 
chloride by a hot, strong solution of corrosive sublimate, while 
the oxides are not affected. The filtrate may be treated gravi- 
metrically or volumetrically (Wilner). 

Proportional Weights of Equivalent Quantities of Iron and its 

Salts. 



Metal .... 
Ferric oxide . . 
Ferric hydrate . 
Ferric chloride . 
Ferric sulphate . 
Ferrous sulphate 



Fe 2 . . . . 
Fe 2 3 . . . 
Fe,6HO . . 

Fe 2 Cl c . . . 
Fe 2 3SO, . . 
2(FeSO„7H.,0) 



111.8 
159.8 
213.8 
324.2 
399.8 
555.8 



ARSENICUM. 

Arsenic (As 2 3 ) is usually estimated volumetrically (vide p. 
573). With certain precautions arsenicum may also be pre- 
cipitated and weighed as sulphide (As 2 S 3 ). 

Process 1. — The pure, white, massive arsenic (about 0.2 grm.) 
is dissolved in a flask in a small quantity of water containing 
bicarbonate of sodium or potassium, the liquid being heated. 
A slight excess of hydrochloric acid is then added, and sul- 



ESTIMATION OF ARSENICUM. 651 

phuretted hydrogen gas passed through the solution so long as 
a precipitate falls, the mouth of the flask being stopped by a 
plug of cotton-wool (to prevent undue access of air and conse- 
quent decomposition of the gas, resulting in precipitation of 
sulphur). The mixture is warmed in the flask, and carbonic 
acid gas passed through it until the odor of sulphuretted hydro- 
gen has nearly disappeared ; the precipitate collected on a tared 
filter, washed as quickly as possible with hot water containing 
a little sulphuretted hydrogen, dried in a water-oven, and 
weighed. 197.8 parts of arsenic should yield 245.8 of sul- 
phide of arsenicum. 

Process 2.— The arsenicum must be present in the arsem'c 
condition. If the operator is not certain that this is the case, 
the solution must be warmed with a little hydrochloric acid 
and a few grains of chlorate of potassium added until a distinct 
odor of chlorous vapor is evolved, which is then allowed to 
escape by continued application of heat. To the solution 
thus obtained ammonia, which must produce no turbidity, is 
added in excess, and then magnesia mixture (see p. 665). The 
solution is set aside for twenty-four or forty-eight hours. The 
precipitate is collected on a filter and washed with as little 
ammonia-water (1 to 3) as possible until the filtrate ceases to 
give a reaction for chlorides. The precipitate is then dried on 
the filter, the precipitate and filter-paper burned, and the whole 
gently ignited in a crucible and weighed. The residue is rep- 
resented by the formula (Mg. 2 As 2 7 ). 

ANTIMONY. 

The metal is precipitated in the form of sulphide (Sb 2 S 3 ), 
with the precautions observed in estimating arsenicum, a small 
quantity of tartaric acid, as well as hydrochloric, being added 
to prevent the precipitation of an oxysalt. If the sulphuretted 
hydrogen be passed through a hot solution, the particles of pre- 
cipitate aggregate better, and the latter may be more quickly 
filtered out and washed. Tha experiment may be performed 
on about half a gramme of pure tartar-emetic : the salt should 
yield slightly more than half its weight (50.6 per cent.) of 
sulphide. According to Fresenius, the sulphide dried at 100° 
C. still contains 2 per cent, of water, and must be heated in a 
current of carbonic acid gas until it turns from an orange to a 
black color before all moisture is expelled. In the United 
States Pharmacopoeia the purity of tartar-emetic (Antimonium 
Tartaratum) and the strength of solution of chloride of anti- 
mony (Liquor Autimonii Chloiidi) are determined by the 



652 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

above process. Sulphurated Antimony of official quality, when 
dissolved in hydrochloric acid and the solution boiled and 
poured into a considerable volume of water, should yield a 
precipitate of oxychloride, which, after washing and drying, 
should weigh 85 per cent, of the sulphurated antimony. 

(For the volumetric estimation of antimony in antimonious 
salts, see p. 573.) 

COPPER. 

Copper is precipitated from its solutions and weighed (1) as 
metal (Cu 2 ) or (2) as oxide (CuO). 

Process 1. — Dissolve about half a gramme of dry crystal- 
lized sulphate of copper in a small quantity of water in a tared 
porcelain crucible or beaker, acidulate with hydrochloric acid, 
introduce a fragment or two of pure zinc, cover the vessel with 
a watch-glass, and set aside till evolution of hydrogen has 
ceased and the still acid liquid is colorless. The copper is 
then washed with hot water by decantation until no trace of 
acid remains, the precipitate drained, rinsed with strong spirit 
of wine, dried in the water-oven, and weighed. 

Process 2. — About three-fourths of a gramme of sulphate 
of copper is accurately weighed, dissolved in half a litre of 
water, the liquid boiled; dilute solution of potash or soda is 
then added till no more precipitate falls, ebullition continued 
for a short time, and the beaker set aside ; the supernatant 
liquid is decanted, the precipitate boiled with water, twice or 
thrice collected on a filter, washed, dried, transferred to a cru- 
cible, the filter incinerated, and its ash moistened with a drop 
of nitric acid ; the whole is finally heated strongly, cooled, and 
weighed. 

Process 3. — From a solution acidulated by sulphuric acid 
and placed in a platinum crucible copper may be entirely de- 
posited in a coherent form by a weak current of electricity, 
the crucible being connected with the zinc pole of the battery, 
a platinum spatula suspended in the solution forming the posi- 
tive pole. The crucible may afterward be freed from the de- 
posited copper by nitric acid. 

249.2 parts of sulphate of copper yield 79.2 of oxide or 
63.2 of metal. 

Other processes are occasionally employed. 

BISMUTH. 

Dissolve 0.3 or 0.4 grm. of pure oxycarbonate of bismuth 
(2Bi 2 2 C0 3 ,H 2 0) (Bismuthi Subcarbonas, U. S. P.) in a small 



ESTIMATION OF MERCURY. 653 

quantity of hydrochloric acid, dilute with water slightly acidu- 
lated by hydrochloric acid, pass excess of sulphuretted hydro- 
gen through the liquid, collect the precipitate on a tared filter, 
wash, dry at 100° C, and weigh. The sulphide must not be 
exposed too long in the water-oven, or it will increase in 
weight, owing to absorption of oxygen ; hence it should be 
tested in the balance every half hour during desiccation. 521 
of oxycarbonate should yield 516 of sulphide (Bi 2 S 3 ). The 
atomic weight of bismuth is 210. 



MERCURY. 

This element may be (1) isolated and estimated in the form 
of metal, or precipitated and weighed as (2) mercurous chlo- 
ride, or (3) mercuric sulphide. 

Process 1. — The process by which the metal itself is sepa- 
rated is one of distillation into a bulb surrounded by water. 
About half a metre of the difficultly fusible German glass 
known as combustion-tubing is sealed at one end after the 
manner of a test-tube (Fig. T9) ; a mixture of bicarbonate of 
sodium and dry chalk is then dropped into the tube to the 
height of 2 or 3 centimetres, and, next, several small frag- 
ments of quicklime so as to occupy another centimetre : a 
mixture of about a gramme of pure calomel or corrosive sub- 
limate with enough powdered quicklime to occupy 10 or 12 
centimetres of the tube is added ; then the lime-rinsings of the 
mixing-mortar, a layer of a few centimetres of powdered quick- 
lime, and finally a plug of asbestos (a fibrous mineral unaf- 

Figs. 79, 80, 81. 



fected by heat), The whole powder should occupy two-thirds 
of the length of the tube. The part of the tube just above 
the asbestos is now softened in the blowpipe-flame and drawn 
out about a decimetre to the diameter of a narrow quill ; it 
is again drawn out to the same extent at a point about two 
or three centimetres nearer the mouth, and any excess of tub- 
ing cut oil". The bulb thus formed may be enlarged by soften- 
ing and blowing. The tube is next softened at a point close 



654 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

to but anterior to the asbestos, and bent to form an obtuse 
angle ; the tube is then softened close to the bulb and slightly 
bent, so that the bulb may be parallel with the large tube ; then 
softened on the other side of the bulb, and the terminal tube 
bent to an obtuse angle, so that, the tube being held in a hori- 
zontal position, the bulb may be sunk in water and the terminal 
tube point upward (Fig. 81). The long tube is now laid in 
the gas-furnace found in most laboratories (Fig. 82), a basin 
so placed that the bulb of the apparatus may be cooled by 
being surrounded by water, the part of the tube occupied by 
asbestos heated to redness, and the flame slowly lengthened 
until the whole tube is red hot. Under the circumstances just 
described the mercurial compound volatilizes, is decomposed by 
the lime, and its acidulous radical fixed, the mercury carried to 
and condensed in the bulb, the carbonic acid gas evolved from 
the bicarbonate of sodium and chalk washing out the last por- 
tions of mercury vapor from the tube. When the distillation 
is considered to be complete, the dish of water is removed, the 
bulb dried, and then detached by help of a file at a point 
beyond any sublimate of mercury. The bulb is lastly weighed, 
the mercury shaken or dissolved out, and the tube again dried 
and weighed. 

Process 2. — The process by which mercury is separated in 
the form of calomel consists in adding hydrochloric and phos- 
phorous acids (vide p. 348) to an aqueous or even acid solu- 

Fig. 82. 




Distillation of Mercury for Quantitative Purposes. 



tion of a weighed quantity of the mercurial compound, setting 
the mixture aside for twelve hours, collecting the precipitate 
on a tared filter, washing, drying at 100° C, and weighing 
(Rose). The experiment may be tried on half a gramme to a 
gramme of corrosive sublimate. 

Process 3.— Two or three decigrammes of corrosive subli- 
mate are dissolved in water, the solution acidulated with hy- 



ESTIMATION OF LEAD. 655 

drochloric acid, excess of sulphuretted hydrogen passed through 
it, the precipitate collected on a tared filter, washed with cold 
water, dried at 100° C, and weighed. 

Proportional Weights of Equivalent Quantities of Mercury and 
its Salts. 

Metal ...... Hg 199.7 

Mercurous chloride . . . HgCl 235.1 

Mercuric chloride . . . HgCl 2 270.5 

Mercuric sulphide . . . HgS 231.7 

LEAD. 

Lead is generally estimated either as (1) oxide, (2) sulphate, 
(3) chromate, or (4) metal. 

Process 1. — Weigh out 1 or 2 grammes of pure acetate of 
lead in a covered crucible previously tared, and heat slowly 
until no more vapors are evolved. Remove the lid, stir down 
the carbonaceous mass with a clean iron wire, and keep the 
crucible in the flame so long as any carbon remains unconsumed. 
Introduce some fragments of fused nitrate of ammonium, and 
again ignite until no metallic lead remains and all excess of 
the nitrate has been decomposed. Cool and weigh the result- 
ing oxide (PbO). 

Process 2. — Dissolve 0.4 or 0.5 of a gramme of acetate of 
lead in a small quantity of water, drop in diluted sulphuric 
acid, add to the mixture twice its bulk of methylated spirit of 
wine, and set aside. Decant the supernatant liquid, collect the 
sulphate on a filter, wash with spirit, dry, transfer to a porce- 
lain crucible, removing as much of the sulphate as possible 
from the paper, incinerate on the crucible-lid (not in the plati- 
num coil, for the particles of reduced lead would unite with the 
platinum by fusion), ignite, cool, and weigh. 

Process 3. — About half a gramme of acetate of lead is dis- 
solved in 200 or 300 c.c. of water, acetic acid added, and then 
solution of red chromate of potassium. Collect the precipitate 
on a tared filter, wash, dry at 100° C, and weigh. 

Process J/.. — In certain cases, notably in that of commercial 
white lead, the lead may be estimated in the metallic state by 
means of cyanide of potassium. The lead paint (about 20 
grammes) is weighed and carefully incinerated. The residue, 
a mixture of metallic lead and oxide of lead, is then mixed 
with several times its bulk of cyanide of potassium and the 
whole heated to fusion. With careful manipulation the lead 
collects in one globule, which, after cooling, may readily be 



6o6 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

separated from the mixed cyanide and cyanate and weighed. 
White lead, commercially pure, should contain 74 per cent, of 
lead. 

Proportionate Weights of Equivalent Quantities of Lead and 
its Salts. 



Metal . 
Acetate . 
Oxide 
Sulphate 
Chromate 



Pb 206.5 

Pb2C 2 HA,2H. 2 . 378.5 

PbO 222.5 

PbS0 4 302.5 

PbOO, .... 322.9 



SILVER. 

Compounds of silver which are readily decomposed by heat 
are estimated in the form of (1) metal, others usually as (2) 
chloride (AgCl), but sometimes as (3) cyanide (AgNC). 

Process 1. — Heat about a gramme of oxide of silver (Ag 2 0) 
in a tared crucible, cool, and weigh. 231.4 of oxide yield 215.4 
of metal. " 29 grains heated to redness yield 27 grains of 
metallic silver." — Brit. Pharm. 

Process 2. — Dissolve 0.4 or 0.5 grm. of pure dry crystals of 
nitrate of silver in water, acidulate with two or three drops of 
nitric acid, slowly add hydrochloric acid, stirring rapidly, until 
no more precipitate falls. Pour off the supernatant liquid 
through a filter, wash the chloride of silver once or twice with 
hot water, transfer to the filter, complete the washing, and dry. 
After removing as much as possible of the precipitate from the 
paper to the crucible, burn the filter, letting its ash fall on the 
inverted lid of the crucible, moisten with a drop of nitric acid, 
warm, add a drop of hydrochloric acid, evaporate to dryness, 
replace the lid on the crucible, unite the whole until the edges 
of the mass of chloride begin to fuse ; cool and weigh. 169.7 
of nitrate yield 143.1 of chloride. According to the United 
States Pharmacopoeia, 10 parts of nitrate should thus yield 
8.4 of chloride, while 20 parts of " moulded nitrate of silver " 
should yield 16 of chloride, and the filtrate from the chloride 
evaporated to dryness should leave no residue, indicating ab- 
sence of nitrates of potassium or sodium and other similar 
adulterants. 20 parts of " diluted nitrate of silver " should 
yield 8.4 of chloride ; 10 parts of " oxide of silver " should 
yield 12.36 of chloride. 

Process 3. — Cyanide of silver may be collected on a tared 
filter and dried at 100° C. 169.7 of nitrate yield 133.7 of 
cyanide. 



ESTIMATION OF SILVER. 657 

Silver and its salts may be volumetrically estimated by a 
standard solution of chloride of sodium. 

Cupellation. — The amount of silver in an alloy may be also deter- 
mined by a dry method. The metal is folded in a piece of thin sheet 
lead, placed on a cupel (cupella, little cup, made of compressed bone- 
earth), and heated in a furnace, the cupel being protected from the 
direct action of flame by a muff-shaped or, rather, oven-shaped, case 
termed a muffle. The metals melt, the baser become oxidized, the 
oxide of lead fusing and dissolving the other oxides ; the fluid oxides 
are absorbed by the porous cupel, a button of pure silver remaining. 
An alloy supposed to contain 95 per cent, of silver requires about 
three times its weight of lead for successful cupellation ; if 92J per 
cent. (English silver coin), between five and six times its weight of 
lead is necessary. 



QUESTIONS AND EXERCISES. 

1048. Explain the gravimetric process by which the strength of the 
official solutions of ferric chloride, nitrate, and sulphate is deter- 
mined. 

1049. Mention the various amounts of ferrous and ferric salts 
equivalent to 100 parts of metal. 

1050. State the precautions necessary to be observed in estimating 
arsenicum or antimony in the form of sulphide. 

1051. In what form are the official compounds of bismuth weighed 
for quantitative purposes ? 

1052. Give an outline of the process by which mercury may be 
isolated from its official preparations and weighed in the metallic 
condition. 

1053. Describe three methods for the quantitative analysis of salts 
of lead, and the weights of the respective precipitates, supposing 
0.56 of crystallized acetate to have been operated on in each case. 

1054. Describe the process by which silver is estimated in the 
forms of metal, chloride, and cyanide. 

1055. What proportions of nitrate of silver are indicated, respec- 
tively, by 15 of metal, 9.8 of chloride, and 8.1 of cyanide? 

1056. Describe cupellation. 



I 



GRAVIMETRIC ESTIMATION OF THE ACIDULOUS 
RADICALS OF SALTS. 

CHLORIDES. 

Free chlorine (chlorine-water) and compounds which by ac- 
tion of acids yield free chlorine (Chlorinated Lime, Chlori- 
nated Soda, and their official solutions) are estimated volumet- 
rically by a standard solution of hyposulphite of sodium (vide 
p. 636). The amount of combined chlorine in pure chlorides 



658 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

(HC1, NaCl) may also be determined by volumetric analysis 
with a standard solution of nitrate of silver (p. 624). 

Combined chlorine is gravimetrically estimated in the form 
of chloride of silver, the operation being identical with that 
just described for silver salts (p. 657). 58.4 parts of pure, 
colorless, crystallized chloride of sodium (rock-salt) yield 
143.1 of chloride of silver. 

IODIDES. 

Free iodine is estimated volumetrically by solutions of hypo- 
sulphite of sodium (vide p. 579). 

Combined iodine is determined gravimetrically in the form 
of iodide of silver, the operations being conducted as with chlo- 
ride of silver. Iodide of potassium may be used for an experi- 
mental determination: Ivl=165.1 should yield Agl=234.3. 
Of iodide of cadmium (Cadmii Iodidum, B. P., 1867) it is stated 
that " 10 grains dissolved in water, and nitrate of silver added 
in excess, give a precipitate which, when washed with water 
and afterward with half an ounce of solution of ammonia, 
and dried, weighs 12.5 grains." 

In presence of chlorides and bromides the iodine in iodides 
may be precipitated and weighed as iodide of palladium. 

Moisture in iodine is estimated by loss on exposing a weighed 
quantity of iodine in a capsule over a dish of sulphuric acid 
under a small bell-jar, or by adding to a weighed sample live 
or six times as much mercury or twice as much zinc, and a 
little water, drying and weighing. The product is the amount 
of metal employed plus that of the dry iodine in the sample. 

BROMIDES. 

Free bromine may be estimated by shaking with excess of 
solution of iodide of potassium, and then determining the 
equivalent quantity of liberated iodine by a standard solution 
of hyposulphite of sodium (p. 636). 

The bromine in bromides may be precipitated and weighed 
as bromide of silver, the manipulations being the same as those 
for chloride of silver : 0.2 to 0.3 of pure bromide of potassium 
may be used for an experimental analysis. 

Ammonii Bromidum, U. S. P. : "1 gm. of the powdered and 
dry salt, when completely precipitated by nitrate of silver, 
yields, if perfectly pure, 1.917 gm. of dry bromide of silver." 
Calcii Bromidum, U. S. P. : "1 gm of the dry salt, when com- 
pletely precipitated by nitrate of silver, yields, if perfectly 
pure, 1.878 gm. of dry bromide of silver." 



ESTIMATION OF NITRATES. 



659 



CYANIDES. 

The hydrogen cyanide (hydrocyanic acid) is usually esti- 
mated volumetrically (vide p. 624). 

From all soluble cyanides cyanogen may be precipitated by 
nitrate of silver after acidulating with nitric acid, the cyanide 
of silver collected on a tared filter, dried at 100° C., and 
weighed. 

Of the official Diluted Hydrocyanic Acid it is stated that 
100 grains (or 110 minims), precipitated by solution of nitrate 
of silver, yield 10 grains of dry cyanide of silver. 



Silver . . 
Cyanogen 



Cyanide of Silver. 



Ag 

CN 



In 1 molec. wt. 

. 107.7 . 

. 26.00 . 

133.7 



In 100 parts. 

. 80.55 
. 19.45 
T00OK) 



NITRATES. 

Nitrates cannot be estimated by direct gravimetric analysis, 
none of the basylous radicals yielding a definite nitrate insolu- 
ble in water. With some difficulty they may be determined by 
indirect volumetric methods. 

Process. — The following (Thorpe's) method depends upon the 
fact (Gladstone and Tribe) 
that when zinc upon which Fig. 83. 

copper is deposited in a 
spongy form is boiled with 
water hydrogen is evolved. 
Thorpe found that in a solu- 
tion containing nitrates the 
nascent hydrogen converts 
the whole of the nitrogen 
of the nitrates into ammo- 
nia, which may be collected 
and estimated. (The oxy- 
gen of the nitrate is simul- 
taneously converted into wa- 
ter, the nitrate-metal into 
hydrate, and the zinc into 
hydrate of zinc. The power 
of the copper-zinc couple is 
considered to depend largely on the hydrogen absorbed by th< 
finely-divided metal.) 




Estimation >>f Nitrate; 



660 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

An apparatus such as shown in Fig. 83 should be con- 
structed. A flask (about 100 c.c.) is fitted with an India- 
rubber cork, perforated for a delivery-tube, which should be 
of strong glass tubing of about quarter-inch bore, and for a 
stoppered funnel, which should have about half the capacity 
of the flask. The whole is supported by a clamp or on wire- 
gauze. The outer jar shown in the figure should have a capa- 
city of 2 or 3 litres, and the inner receiving-jar should be cap- 
able of holding 200 c.c. The latter is fitted with an India- 
rubber cork, perforated for the delivery-tube, and for another 
tube containing fragments of glass. 

A few strips of clean zinc are boiled in a beaker with a 3-per 
cent, solution of sulphate of copper, the operation being re- 
peated with a fresh portion of solution six consecutive times. 
A thick coating of finely-divided copper is deposited. The 
pieces of metal are well washed and introduced into the flask, 
which is then half filled with pure water. To avoid transfer- 
ence, the flask itself may be used instead of the beaker. The 
funnel also is filled with pure water. Into the inner receiver 
is put a little pure water very slightly acidulated with hydro- 
chloric acid, and the glass fragments are also moistened with 
the dilute acid (to prevent possible loss of ammonia). Water 
is now placed around the inner receiver in the outer jar, and, 
the connections being sound, heat is applied with the view of 
freeing the apparatus itself from any trace of ammonia. When 
the contents of the flask are evaporated nearly to dryness, pure 
water is admitted from the funnel until the flask is again about 
half full (the funnel should be filled again at once), and the 
distillation carried on as before. This must be repeated until 
no further trace of ammonia is evolved, when the apparatus is 
ready for use. On each occasion that the apparatus is used it 
must be freed from ammonia in this way. A suitable quantity 
of the substance to be estimated is now introduced (in the case 
of potable waters the prepared solid .residue from 100 c.c, with 
an added fragment of recently ignited lime, the size of a hemp- 
seed, to promote the evolution of the ammonia), and water 
added, if necessary, until the flask is half full. Heat is now 
applied, and the operation conducted in the manner already 
described until ammonia ceases to come over — a point which 
always occurs in the case of water-residues when the flask has 
been refilled twice and the distillate is about 100 c.c. The 
warm water from the upper part of the cooling-jar may be re- 
moved by a siphon or otherwise, cold water being introduced 
from time to time. 

The ammonia being all evolved, disconnect the flask and re- 



ESTIMATION OF NITRATES. 661 

ceiver simultaneously (unless washing-bottle tubes are fitted), 
and treat the contents of the latter by the Nessler method, 

described on page 615. Urea yields but traces of ammonia 

by this process, and neither the sulphates nor chlorides of the 

alkali-metals affect the result. The method is only applicable 

to highly dilute solutions of nitrates, for with stronger solu- 
tions oxides of nitrogen are formed and escape. 

Another process (Pelouze's improved by Fresenius) consists 
in adding the nitrate to an acid solution of a ferrous salt of 
known strength, and, when reaction is complete, estimating the 
amount of ferrous salt unattacked by volumetric solution of red 
chromate or of permanganate. Three molecular weights of con- 
verted ferrous salt indicate one molecular weight of nitric acid. 
Regeneration of nitric or nitrous acids by aerial oxidation of 
the nitric oxide evolved is prevented either by a current of 
carbonic acid gas or by using a closed flask in which is a Bun- 
sen valve (i. e. a short attached piece of India-rubber tubing 
closed at the free extremity and having a sharp longitudinal 
slit in it a third of an inch long — a slit by which gases can 
escape, but cannot re-enter). 

Potassii Nitras, U. S. P. : " If 1 gm. of the dried salt be 
moistened with 1 gm. of concentrated sulphuric acid, and the 
mixture be kept at a red heat until it ceases to lose weight, the 
residue should weigh 0.86 gm." 

SULPHIDES. 

Process 1. — Soluble sulphides (H 2 S, NaHS, e. g.~) may be 
determined volumetrically by adding to the aqueous liquid a 
measured excess of an alkaline solution of arsenic of known 
strength, neutralizing by hydrochloric acid, diluting to any 
given volume, filtering off the sulphide of arsenicum precipi- 
tated, taking a portion of the filtrate equal to half or a third 
of the original volume, and, after neutralizing by acid carbo- 
nate of sodium, estimating the residual arsenic by the standard 
iodine solution (vide p. 572). The process may be tried on a 
measured volume of sulphuretted hydrogen (the weight of 
which is easily calculated : 1 litre of hydrogen = 0.0896 
gramme) absorbed by a strong solution of soda or potash. 

Process 2. — Sulphur and sulphides may also be quantita- 
tively analyzed by oxidizing to sulphuric acid and precipitating 
in the form of sulphate of barium. A couple of decigrammes 
of a pure metallic sulphide may be decomposed by careful 
deflagration with a mixture of chlorate of potassium and car- 
bonate of sodium, the product dissolved in water, acidulated 



662 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

with hydrochloric acid, solution of chloride of barium added, 
and the precipitated sulphate of barium purified and collected 
as described in connection with the estimation of barium 
(p. 645). Many sulphides may be oxidized in a flask by 
chlorate of potassium and hydrochloric acid, and then precip- 
itated by chloride of barium. Experimental determinations 
may also be made on a weighed fragment of sulphur, about 0.1 
grm., cautiously fused with a solid caustic alkali, and the product 
oxidized while hot by the slow addition of powdered nitrate or 
chlorate of potassium, or, when cold, by treatment with chlorate 
of potassium and hydrochloric acid, and subsequent precipita- 
tion by chloride of -barium. 

Note. — Fusions performed by help of a gas-lamp must be carefully 
conducted, for any alkali that may creep over the side of a crucible 
will certainly absorb sulphurous acid from the products of combus- 
tion of the gas, and error result. 

Process 3. — Soluble sulphides may also be treated with ex- 
cess of an alkaline arsenite, arsenous sulphide be then precip- 
itated by the addition of hydrochloric acid, and the precip- 
itate collected and weighed with the usual precautions (vide 
p. 593). 

Weights of Equivalent Quantities of Sulphur and its 
Compounds. 

Sulphur S 32 

Sulphuretted hydrogen . H 2 S 34 

Sulphate of barium . . . BaS0 4 232.8 

Arsenious sulphide . . . (As 2 S 3 ) -4- 3 . . . 82 

Bisulphide of iron . . . (FeS 2 ) -*- 2 . . . . 60 

Sulphide of lead . . . . PbS 238.5 

SULPHITES. 

Sulphites are usually estimated volumetrically by a standard 
solution of iodine (vide p. 629). Sulphites insoluble in water 
are diffused in that menstruum, hydrochloric acid added, and 
the iodine solution then dropped in. 

If necessary, sulphites may be estimated gravimetrically by 
oxidation and precipitation in the form of sulphate of barium. 

SULPHATES. 

These salts are always precipitated and weighed as sulphate 
of barium, the manipulations being identical with those per- 
formed in the determination of barium by means of sulphates 



ESTIMATION OF SULPHATES. 663 

(vide p. 645). The purity of Sulphate of Sodium (Sodii Sul- 
phas, U. S. P.), and the presence of not more than a given 
amount of sulphuric acid in vinegar (Acetum, B. P.), are 
directed, in the British Pharmacopoeia, to be ascertained by 
this process. Ten grains of sulphate of sodium yield 7.23 of 
sulphate of barium. Five ounces of vinegar should yield not 
more than about one-third of a gramme of sulphate of barium. 
The amount of free sulphuric acid or hydrochloric acid in 
vinegar, lemon-juice, lime-juice, etc. may also be ascertained 
volumetrically by adding a known quantity of standard solu- 
tion of soda, evaporating to dryness, incinerating, dissolving 
in water, and, by standard acid, estimating the quantity of soda 
still remaining free. The soda lost indicates the amount of 
free mineral acid (Hehner). Thresh estimates the chlorine in 
a sample of vinegar, adds a known additional amount of chlo- 
rine, preferably in the form of chloride of barium, evaporates, 
ignites ; treats with water, adds bicarbonate of sodium to re- 
move excess of barium, filters, and again estimates the chlorine. 
A loss of 70.8 of chlorine (Cl 2 ) indicates 98 of free sulphuric 
acid (H 2 S0 4 ). The method of estimating free sulphuric, nitric, 
or hydrochloric acid proposed by Spence and Esilman is 
founded on their power of decolorizing a standard solution of 
ferric acetate. 

Proportional Weights of Equivalent Quantities of Sulphates. 

The sulphuric radical . . . SO* 96 

Sulphuric acid H 2 S0 4 98 

Sulphate of barium . . . BaS0 4 232.8 

CARBONATES. 

Carbonates are usually estimated by the loss in weight they 
undergo on the addition of a strong acid. 

Process 1. — A small light flask is selected — of such a size 
that it can be conveniently weighed in a delicate balance. Two 
narrow glass tubes are fitted to the flask by a cork ; the one 
straight, extending from about two or three centimetres above 
the cork to the bottom of the flask ; the other cut off close to 
the cork on the inside and curved outward, so as to carry a 
thin drying-tube horizontally above the flask. (See Fig. 84.) 
The drying-tube is nearly filled with small pieces of chloride 
of calcium, a plug of cotton-wool preventing escape of any 
fragments at either end, and is attached by a pierced cord to 
the free extremity of the curved tube of the flask. A weighed 
quantity of any pure soluble carbonate is placed in the flask, 




664 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

a little water added, a miniature test-tube containing sulphuric 
acid lowered into the flask by a thread and supported so that 
the acid may not flow out, the cork in- 
serted, the outer end of the piece of the Fig- 84. 
straight glass tube closed by a fragment 
of cork or wax, and the whole weighed. 
The apparatus is then inclined so that the 
oil of vitriol and carbonate may slowly 
react; carbonic acid gas is evolved and 
escapes through the horizontal tube, any 
moisture being retained by the chloride of 
calcium. When effervescence has ceased, 
the gas still remaining in the vessel is 

Sucked OUt^ this is accomplished by Estimation of Carbonates. 

adapting a piece of India-rubber tubing 

to the end of the drying-tube, removing the small plug 
from the straight tube, and aspirating slowly with the mouth 
for a few minutes. If the heat produced by the action of oil 
of vitriol and solution is considered insufficient to expel all the 
carbonic acid from the liquid, the plug is again inserted in the 
tube and the contents of the flask gently boiled for some seconds. 
When the apparatus is nearly cold more air is again drawn 
through it, and the whole finally weighed. The loss is due to 
carbonic acid gas (C0 2 ), from the weight of which that of any 
carbonate is ascertained by calculation. Carbonates insoluble 
in water may be attacked by hydrochloric instead of sulphuric 
acid ; granulated mixtures of carbonates and powdered tartaric 
or citric acid by enclosing the preparation in the inner tube 
and placing water in the flask, or vice versa. The apparatus 
also may be modified in many ways to suit the requirements, 
convenience, or practice of the operator. 

Process 2. — Carbonates from which carbonic acid gas is 
evolved by heat may be estimated by the loss they experience 
on ignition. 

Process 3. — Free carbonic acid gas may be absorbed by a 
solid stick of potash or a strong alkaline solution, the loss in 
volume of the gas or mixture of gases indicating the amount 
originally present. 

Weights of Equivalent Quantities of Carbonic Acid Gas and 
certain Carbonates. 

Carbonic acid gas C0 2 44 

Carbonic acid H. 2 C0 3 .... 62 

Anhydrous carbonate of sodium . Na 2 C0 3 .... 106 



ESTIMATION OF OXALATES. 665 

Crystalline carbonate of sodium . Na 2 CO 3 ,10H 2 O. . 286 

Anhydrous carbonate of potassium . K 2 C0 3 . . . . 138 

Crystalline carbonate of potassium. K 2 C0 3 -hl6%aq.l64. 285 

Carbonate of calcium CaC0 3 .... 100 

OXALATES. 

Process 1. — The oxalic radical is usually precipitated in the 
form of oxalate of calcium and weighed as carbonate, the 
manipulations being identical with those observed in the esti- 
mation of calcium (vide p. 646). The experiment may be 
performed on 0.3 or 0.4 grm. of pure crystallized oxalic acid, 
126 parts of which should yield 100 of carbonate of calcium. 

Process 2. — Oxalates may also be determined by conversion 
of their acidulous radical into carbonic acid gas, and observa- 
tion of the weight of the latter. The oxalate, water, and 
excess of black oxide of manganese are placed in the carbonic 
acid apparatus (page 665), a tube containing oil of vitriol low- 
ered into the flask, the whole weighed, and the operation com- 
pleted as for carbonate. From the following equation it will 
be seen that every 88 parts of carbonic acid gas evolved indi- 
cate the presence of 126 parts of crystallized oxalic acid or an 
equivalent quantity of other oxalate : — 

Na,C 2 4 + Mn0 2 + 2H 2 SG 4 = MnS0 4 + Na 2 S0 4 + 2H 2 

-h 2C0 2 . 
The black oxide of manganese used in this experiment must 
be free -from carbonates. The amount of materials employed 
is regulated by the size of the vessels. 

PHOSPHATES. 

Process 1. — From phosphates dissolved in water the phos- 
phoric radical may be precipitated and weighed in the form of 
pyrophosphate of magnesium, the details of manipulation being- 
similar to those observed in estimating magnesium (vide p. 
647). Half a gramme or rather more of pure dry crystallized 
phosphate of sodium may be employed in experimental deter- 
minations. The official phosphate of ammonium (Amnion ii 
Phosphas, U. S. P.) is quantitatively analyzed by this method. 
" 2 gm. of the salt, dissolved in water and precipitated with 
test-mixture of magnesium, yields a crystalline precipitate, 
which, when washed with diluted water of ammonia, dried, 
and ignited, should weigh 1.68 gm." Half a gramme or less 
is a more convenient quantity if the operations be conducted 
with care. Solution of ammonia-sulphate of magnesium (U. S. 
P.) is prepared by dissolving 1 part of sulphate of magne- 
sium, 2 of chloride of ammonium, and 4 of solution of ammo- 



666 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

nia (10-per cent. NH 3 ) in 8 of distilled water; such a solution 
is of considerable use if several phosphoric determinations are 
about to be made. 

Process 2. — Free phosphoric acid is most readily determined 
as phosphate of lead (Pb 3 2P0 4 ). Of the official solution of 
phosphoric acid it is stated that " on pouring 5 gm. of phos- 
phoric acid upon 10 gm. of oxide of lead free from carbonate 
of lead and from moisture, evaporating and igniting, a residue 
will be obtained which should weigh 11.81 gm." In the case 
of the diluted acid, 5 gm. with 5 of lead oxide should yield 
5.36. The oxide of lead must be quite pure : it should be 
prepared by digesting red lead in warm dilute nitric acid, 
washing, drying, and heating a resulting puce-colored plumbic 
oxide in a covered porcelain crucible. The increase in weight 
obtained on evaporating a given amount of solution of phos- 
phoric acid with a known weight of perfectly pure oxide of 
lead (PbO) may be regarded as entirely due to phosphoric an- 
hydride (PA), 

3PbO + P 2 5 == Pb 3 2P0 4 , 
the actual reaction being 

3PbO + 2H S P0 4 = Pb 3 2P0 4 + 3H 2 0. 
From these equations and the table of atomic weights (vide 
Appendix) the percentage of phosphoric acid (H 3 P0 4 ) in any 
specimen of its solution may be easily calculated. 

Process 3. — The strength of pure solution of phosphoric 
acid may be ascertained by specific gravity and reference to 
Tables. 

Process Jf.. — Bone-earth, " superphosphate," the Calcis Phos- 
phas of pharmacy, and other forms of phosphate of calcium 
known to be tolerably free from iron or aluminium, may be 
estimated by treating about half a gramme with hydrochloric 
acid somewhat diluted, filtering if necessary, warming, precip- 
itating with excess of ammonia, collecting the precipitate 
(Ca 3 2P0 4 ), washing, drying, igniting, and weighing. " Calcis 
PJiosphas" if pure, will in this process lose no weight. 

Process 5. — Insoluble phosphates in ashes, manures, etc. are 
treated as follows: A weighed quantity of the material (1.0 
to 10.0 grm.) is digested in hydrochloric acid diluted with three 
or four times its bulk of water ; filtered (insoluble matter and 
filter being thoroughly exhausted by water) ; ammonia added 
to the filtrate and washings until, after stirring, a faint cloudy 
precipitate is perceptible ; solution of oxalic acid dropped in 
until, after agitation for a few minutes, the opalescence is de- 



ESTIMATION OF PHOSPHATES. 667 

stroyed ; oxalate of ammonia next added, the whole warmed, 
oxalate of calcium removed by nitration, and the filtrate con- 
centrated if very dilute ; the liquid treated with citric acid in 
such quantity that ammonia when added in excess gives a clear 
lemon-yellow solution (Warington), magnesian mixture poured 
in (as in Process 1), and the precipitate of ammonio-magnesian 
phosphate collected, washed, dried, and weighed, as already de- 
scribed in connection with the estimation of magnesium. 

Relative Weights of Equivalent Quantities of Phosphoric 
Compounds. 

Phosphoric acid H 3 P0 4 98 

Pyrophosphate of magnesium . (Mg 2 P 2 7 = 222)-^-2= 

Phosphate of lead . . . . (Pb 3 2P0 4 = 811) - 

Phosphoric anhydride . . . (P 2 5 = 142) 

Phosphate of calcium . . . (Ca 3 2P0 4 = 310) - 

Superphosphate of calcium . (CaH 4 2P0 4 =234- 



2= 


ill 
405.25 


2= 


71 


2= 


155 


2= 


117 



QUESTIONS AND EXERCISES. 

1057. What quantity of pure rock-salt is equivalent to 4.2 parts 
of chloride of silver? Ans. 1.714. 

1058. State the percentage of real iodide of potassium contained 
in a sample of which S parts yield 10.9 of iodide of silver. Ans. 96.3. 

1059. What is the strength of a solution of hydrocyanic acid 10 parts 
of which, by w r eight, yield .9 of cyanide of silver? Ans. 1 .82 per cent. 

1060. JIow are nitrates quantitatively estimated ? 

1061. By what processes may the strength of sulphides be deter- 
mined? 

1062. How much real sulphate of sodium is contained in a specimen 
10 parts of which yield 14.2 of sulphate of barium. Ans. 86.61 per cent. 

1063. Give details of the operations performed in the quantitative 
analysis of carbonates. 

1064. What amount of carbonic acid gas should be obtained from 10 
parts of acid carbonate (or bicarbonate) of potassium ? Ans. 4.4 parts. 

1065. To what operation and what proportion of materials does 
the following equation refer? — 

Na 2 C 2 4 + Mn0 2 + 2II 2 S0 4 = MnS0 4 + Na 2 S0 4 + 2II 2 + 2C0 2 . 

1066. Explain the lead process for the estimation of phosphoric 
acid in the official solution. 

1067. State the amount of superphosphate of calcium equivalent 
to 7.6 parts of pyrophosphate of magnesium. Ans. 8.01. 



SILICATES. 

Silica (SiO,) may be separated from alkaline silicates, or 
from silicates decomposable by hydrochloric acid, by digesting 



668 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

the substance in hydrochloric acid at a temperature of 70° to 
80° C. until completely disintegrated, evaporating to dryness, 
heating in an air-bath, again moistening with acid, diluting 
with hot water, filtering, washing, drying, igniting, and weigh- 
ing. 

ESTIMATION OF WATER. 

Water and other matters readily volatilized are most usually 
estimated by the loss in weight which a substance undergoes 
on being heated to a proper temperature. Thus, in the British 
Pharmacopoeia crystalline gallic acid (H 3 C 7 H 3 5 .H 2 0) is stated 
to lose 9.5 per cent, of its weight at a temperature of 100° C, 
oxalate of cerium (CeC 2 4 ,3H 2 0) 52 per cent, on incineration, 
carbonate of potassium about 16 per cent, on exposure to a red 
heat, sulphate of quinine (2C 20 H 24 N 2 O 2 ,H 2 SO 4 ,7H 9 O) 14.4 per 
cent, at 100° C, arseniate of sodium (Na 2 HAs0 4 ,7H 2 0) 40.38 
per cent, at 149° C, carbonate of sodium (Na 2 CO 3 ,10H 2 O) 60.3 
per cent., phosphate of sodium (Xa 2 HP0 4 ,12H 2 0) 63 per cent., 
and sulphate of sodium (Na 2 SO 4 ,10H 2 O) 55.9 per cent, at a 
low red heat ; oxide of bismuth heated to incipient redness 
should not diminish in weight. 

Process. — One or two grammes of substance is sufficient in 
experiments on desiccation, the material being placed in a 
watch-glass, covered or uncovered porcelain crucible, or other 
vessel, according to the temperature to which it is to be ex- 
posed. Rapid desiccation at an exact temperature may be 
effected by introducing the substance into a tube having some- 
what the shape of the letter U, sinking the lower part of the 
tube into a liquid kept at a definite temperature by aid of a 
thermometer, and drawing or forcing a current of dry air 
slowly through the apparatus. Substances liable to oxidation 
may be desiccated in a current of dried carbonic acid gas. The 
weights of the U-tube before and after the introduction of the 
salt, and after desiccation, give the amount of water sought. 
In all cases the material must be heated until it ceases to lose 
weight, Occasionally it is desirable to estimate water directly 
by conveying its vapor in a current of air through a weighed 
tube containing chloride of calcium and reweighing the tube at 
the close of the operation ; the increase shows the amount of 
water. 

Note. — Highly dried substances rapidly absorb moisture from the 
air ; they must therefore be weighed quickly, enclosed, if possible, 
in tubes (p. 640), a pair of clamped watch-glasses, or a crucible 
having a tightly fitting lid. 



CARBON, HYDROGEN, OXYGEN, NITROGEN. 6G9 

CARBON, HYDROGEN, OXYGEN, NITROGEN. 

The quantitative analysis of animal and vegetable substances is 
either proximate or ultimate. Proximate quantitative analysis in- 
cludes the estimation of water, oil, albumen, starch, cellulose, gum, 
resins, alkaloids, acids, glucosides, ash. It requires the application 
. of much theoretical knowledge and manipulative skill, and cannot 
well be studied except under the guidance of a tutor. One of the 
best of the published works on the subject is by Rochleder, a trans- 
lation of whose monograph will be found in the Pharmaceutical 
Journal, vol. i. 2d ser. pp. 562, 610; vol. ii. 2d ser. pp. 24, 129, 160, 
215, 274, 420, 478. Another is a small book by Professor A. B. 
Prescott, Outlines of Proximate Organic Analysis, Van Nostrand, 
New York. 

Ultimate quantitative organic analysis can only be successfully 
accomplished with the appliances of a well-appointed laboratory — a 
good balance, a gas-furnace giving a smokeless flame (7 or 8 centi- 
metres wide and 70 or 80 centimetres long), special forms of glass 
apparatus, etc. The theory of the operation is simple : A weighed 
quantity of a substance is burnt to carbonic acid gas (C0 2 = 44) and 
water (H 2 = 18), and these products collected and weighed 5 12 
parts in every 44 of carbonic acid gas (= T 3 T ) are carbon, 2 in every 
18 of water (= ^) are hydrogen ; nitrogen if present escapes as gas. 
If nitrogen be a constituent, more of the substance is strongly heated 
with a mixture of the hydrates of sodium and calcium 5 these bodies 
then split up into oxides, oxygen, and hydrogen ; the oxygen burns 
the carbon of the substance to carbonic acid gas, its hydrogen and 
nitrogen appearing as water and ammonia respectively 5 the car- 
bonic acid and water are disregarded, the ammonia collected and 
weighed in the form of a double chloride of platinum and ammonium 
(PtCl 4 2NH 4 Cl = 442.8), of which 28 parts in every 442.8 (= ^) are 
nitrogen. The difference between the sum of the weights of hydro- 
gen and carbon, and the weight of substance taken, is the proportion 
of oxygen in the body, supposing nitrogen to be absent. If nitrogen 
is present, the difference between the sum of the percentage of car- 
bon, hydrogen, and nitrogen, and 100, is the percentage of oxygon. 
Shortly, carbon is estimated in the form of carbonic acid gas, hydro- 
gen as water, nitrogen as ammonia, and oxygen by loss. 

The following is the outline of the necessary manipulation : — 
The source of the oxygen for the combustion of carbon and 
hydrogen is black oxide of copper in coarse powder. 200 or 
300 grammes of this material are heated in a crucible to low 
redness for a short time to expel every trace of moisture ; then 
transferred to store-tubes (Fig. 85) resembling test-tubes, half 

Fig. 85. 



a metre long, and having a slightly narrowed mouth, the tube 
being held in a cloth to protect the hand while the hot oxide 



670 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

is being directly introduced into the mouth of the tube by a 
scooping motion. As soon as the well-corked tube is cool, the 
oxide is poured, portion by portion, into a similar tube (the 
combustion-tube), but somewhat longer, drawn out to a quill 
(bent upward nearty to a right angle) at one end and not con- 
stricted at the mouth. Two such tubes are readily made by 
softening in the blowpipe-flame two or three centimetres of the 
central part of a tube about a metre long, and drawing the 
halves of the tube apart, as shown in the following engraving 
(Fig. 86). The tubes are separated by melting the glass in the 
middle of the quilled portion. A few decigrammes of fused 
chlorate of potassium should first be dropped into the tube. 
After ten or fifteen centimetres of oxide have been poured in, 
about a decigramme of the substance to be analyzed is dropped 
down the tube, then a few grammes of oxide, then another 
decigramme of substance, then more oxide, until three or four 
decigrammes of the body under examination have been added. 
The fifteen or twenty centimetres of alternate layers are next 
thoroughly mixed by a long copper wire having a short helix ; 
more oxide is introduced, the wire cleansed by twisting the 
helix about in the pure oxide, and a plug of dry asbestos 
finally placed on the top of the oxide at about five centimetres 
from the mouth of the tube ; the tube is then securely corked 
and set aside. The substance operated on may be pure white 

Fig. 86. 



sugar, powdered and dried ; the tube in which it is contained 
is weighed before and after the removal of a portion for com- 
bustion ; the loss is the quantity employed in the experiment. 
The combustion-furnace may be such as shown on page 654. 
If the furnace is very powerful or the combustion-tube not of 
the hardest glass, the tube should be enclosed in wire-gauze the 
elasticity of which has been destroyed by heating to redness. 
If the substance under experiment contains nitrogen, the plug 
of asbestos must be displaced by one of copper turnings, which 
serves to reduce any oxides of nitrogen, and thus ensure the 
escape of nitrogen itself. The water produced when the pre- 
pared tube is heated is collected in a small U-tube containing 
pieces of chloride of calcium, or pumice-stone moistened with 



CARBON, HYDROGEN, OXYGEN, NITROGEN. 671 

sulphuric acid (Fig. 87) ; the carbonic acid gas in a series of 
bulbs (Fig. 87) containing solution of potash (sp. gr. about 
1.27). These bulbs may be purchased at any apparatus-shop. 
The chloride-of-calcium tube is fitted by a good cork to the 
combustion-tube, the potash-bulbs by a short piece of India- 
rubber tubing to the chloride-of-calcium tube. The potash- 
bulbs may carry a short light tube containing a rod of caustic 

Fig. 87. 




Chloride-of-Caleium Tubes and Potash-bulbs. 



potash three or four centimetres long ; this serves to arrest any 
moisture that might be carried away from the solution of pot- 
ash by the dried expanded air which escapes during the opera- 
tion. The combustion-tube having been placed in the furnace, 
and the drying-tube and potash-bulbs weighed and detached, 
the gas is lit under the asbestos, and, when the tube is red hot, 
the flame slowly extended until nearly the whole tube is at the 
same temperature, the operation being conducted at such a 
rate that bubbles of gas escape through the potash-bulbs at 
about the rate of one per second. When no more gas passes, 
the extremity of the tube containing the chlorate of potassium 
is gently heated until oxygen ceases to be evolved ; the quilled 
extremity of the combustion-tube is then broken, and air, dried 
and freed from carbonic acid, drawn slowly through the appa- 
ratus by suction through an India-rubber tube fixed on the free 
end of the potash-bulbs ; perfect combustion of carbon and re- 
moval of all carbonic acid gas are thus ensured. The drying- 
tube and bulbs are disconnected and weighed, the increase in 
weight due to carbonic acid gas and water respectively noted, 
and the percentages of carbon, hydrogen, and (by loss) oxygen 
calculated. This method is that of Liebig, with modification 
by Bunsen ; good combustion-furnaces are those known as 
Hofmann's and Griffin's. 

Chromate of lead can be used for combustion in place of oxide 
of copper. Its advantages are, its less hygroscopic nature, and 
the greater readiness with which it yields its oxygen to organic 
bodies when heated with them. It must not. however, be used 
with bodies containing nitrogen, since it would convert so large 
a proportion of the nitrogen into nitric oxide or higher oxide 



672 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

of nitrogen that it would be necessary to use an inconveniently 
long layer of copper turnings to reduce these oxides, and so 
prevent their absorption in the series of bulbs containing the 
solution of potash. Organic bodies, however, containing sul- 
phur, bromine, iodine, or chlorine are burnt with advantage 
by means of chromate of lead. If oxide of copper were used 
with bodies containing sulphur, it would be necessary to place 
an additional tube containing peroxide of lead between the 
chloride-of-calcium tube and the potash-bulbs in order to absorb 
the sulphurous anhydride formed ; this is entirely obviated by 
using chromate of lead, which itself retains the whole of the 
sulphur. Again, if bodies containing chlorine, iodine, or bro- 
mine are burnt by means of oxide of copper, then volatile 
chloride, iodide, or bromide of copper is formed, and, collecting 
in the chloride-of-calcium tube, vitiates the result with regard 
to the hydrogen ; by using chromate of lead, however, the 
chlorine, iodine, and bromine are respectively retained in the 
combustion-tube as chloride, bromide, and iodide of lead. 

In order to render the chromate fit for use, it is first fused 
and poured out on a clean iron plate ; when cool it is powdered, 
and heated in a long tube throughout its whole length, while 
air, dried by passing through chloride of calcium or strong 
sulphuric acid 3 is drawn over it ; when the color of the chro- 
mate changes to brown the heat can be withdrawn and the 
extremity of the tube farthest from the drying apparatus closed, 
so that the air in passing into the tube on cooling may be quite 
dry ; when cool the drying-tube is removed, the extremity 
securely corked, and the carbonate of lead is ready for direct 
transference to the combustion-tube. 

The general manipulations for substances containing nitrogen 
resemble the foregoing so far as the use of a combustion-tube 
and furnace and collection of 
Fig. 88. tne ammoniacal gas are con- 

cerned. The combustion-tube 
must be quilled at one end, and 
about a third of a metre long. 
The soda-lime is made by slak- 
ing quicklime with a solution 
of soda, of such a strength that 
about two parts of quicklime 
Nitrogen-bulbs. shall be mixed with one of hy- 

drate of sodium, drying the prod- 
uct, heating to bright redness, and finally powdering; it should 
be preserved in a well-closed bottle. Some of the soda-lime is 
introduced into the tube, then layers of substance and soda- 




CARBON, HYDROGEN, OXYGEN, NITROGEN. 673 

lime, mixture effected by a wire, more soda-lime added, and 
lastly a plug of asbestos. Bulbs (Fig. 88), known as those of 
Will and Varrentrapp (the originators of the method), contain- 
ing hydrochloric acid of about 25 per cent., are then fitted by 
a cork, and the tube heated in a furnace to a not too bright red 
heat, or some of the produced ammonia may be decomposed. 
When gas ceases to pass and combustion is considered to be 
quite complete, the tube is allowed to cool somewhat. The 
quill is then broken, and aspiration continued slowly until 
ammoniacal gas may be considered to have been all absorbed 
by the acid. The bulls are disconnected, their contents and 
rinsings poured into a small dish, solution of perchloride of 
platinum added, and the operation completed, as in the estima- 
tion of ammonium and potassium salts (vide pp. 642 and 644.). 

Liquids are analyzed by a similar method to that adopted for 
solids, volatile liquids being enclosed in small bulbs having a 
long quill. These are weighed previously to and after the in- 
troduction of the liquid ; just before being dropped into the 
combustion-tube the quill is broken. 

Formula— -From the percentage composition of an organic 
substance an empirical formula may be deduced by dividing 
the weight of each constituent by its atomic weight, and con- 
verting the product into the simplest whole numbers ; a rational 
formula by ascertaining the proportion in which the substance 
unites with a radical or body having a known combining pro- 
portion, -etc. (vide p. 384 to 388). 

Chlorine, bromine, or iodine contained in an organic sub- 
stance is usually estimated by heating to redness a given 
weight of the material with ten times as much pure lime in a 
combustion-tube. Chloride, bromide, or iodide of calcium is 
thus produced. While still hot the tube is plunged into water, 
the mixture of broken glass and powder treated with pure 
diluted nitric acid in very slight excess ; the filtered liquid pre- 
cipitated by nitrate of silver, and the chloride, bromide, or iodide 
of silver collected, washed, dried, and weighed. 

Sulphur, phosphorus, and arscnicum in organic salts may be 
estimated by gradually heating in a combustion-tube 1 part of 
the substance with a mixture of 10 parts nitre, 2 dried carbo- 
nate of sodium (in order to moderate deflagration), and 30 chlo- 
ride of sodium. The product is dissolved in water acidulated 
by nitric acid, the sulphuric radical precipitated and estimated 
as sulphate of barium, the phosphoric and arsenic radicals as 
ammonio-niagnesiuni phosphate or arseniate. 
57 



674 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

QUININE. 

Process of the British Pharmacopoeia for Ascertain- 
ing the Amount of (1) Quinine with Cinchonidine, 
and (2) Total Alkaloids, in the Succirubra or Red 
Cinchona Bark {Cinchona Rubrez Cortex, B. P.). 

1. For Quinine and Cinchonidine. — Mix two hundred grains 
of red cinchona-bark, in No. 60 powder, with sixty grains of 
hydrate of calcium ; slightly moisten the powders with half an 
ounce of water ; mix the whole intimately in a small porcelain 
dish or mortar ; allow the mixture to stand for an hour or two, 
when it will present the characters of a moist, dark-brown 
powder in which there should be no lumps or visible white 
particles. Transfer this powder to a six-ounce flask, add 
three fluidounces of benzolated amylic alcohol, boil them 
together for about half an hour, decant and drain off the liquid 
on to a filter, leaving the powder in the flask ; add more of the 
benzolated amylic alcohol to the powder, and boil and decant 
as before ; repeat this operation a third time ; then turn the 
contents of the flask on to the filter, and wash by percolation 
with more of the benzolated amylic alcohol until the bark is 
exhausted. If, during the boiling, a funnel be placed in the 
mouth of the flask, and another flask filled with cold water 
be placed in the funnel, this will form a convenient condenser 
which will prevent the loss of more than a small quantity 
of the boiling liquid. Introduce the collected filtrate, while 
still warm, into a stoppered glass separator; add to it twenty 
minims of diluted hydrochloric acid, mixed with two fluid- 
drachms of water ; shake them well together, and when the 
acid liquid has separated this may be drawn off, and the 
process repeated with distilled water slightly acidulated with 
hydrochloric acid, until the whole of the alkaloids have been 
removed. The acid liquid thus obtained will contain the 
alkaloids as hydrochlorates, with excess of hydrochloric acid. 
It is to be carefully and exactly neutralized with ammonia 
while warm, and then concentrated to the bulk of three fluid- 
drachms. If now about fifteen grains of tartarated soda, dis- 
solved in twice its weight of water, be added to the neutral 
hydrochlorates, and the mixture stirred with a glass rod, 
insoluble tartrates of quinine and cinchonidine will separate 
completely in about an hour ; and these, collected on a filter, 
washed, and dried, will contain eight-tenths of their weight of 
the alkaloids, quinine and cinchonidine, which, divided by 2, 
represents the percentage of those alkaloids. The other alka- 
loids will be left in the mother-liquor. 



QUININE. 675 

2. For Total Alkaloids. — To the mother-liquor from the pre- 
ceding process add solution of ammonia in slight excess. 
Collect, wash, and dry the precipitate, which will contain the 
other alkaloids. The weight of this precipitate, divided by 2, 
and added to the percentage weight of the quinine and cin- 
chonidine, gives the percentage of total alkaloids. 

De Vrifs Method for the Separation of the Mixed Alkaloids 
from Cinchona- Bark, and De Vrifs Method for the Separation 
and Quantitative Determination of All the Different Cinchona 
Alkaloids. (For these processes the reader is referred to the 
tenth edition of this Manual.) 

Prollius's Method for the Estimation of Total Alkaloids in 
Cinchona-bark, as modified by De Vrij. — The principle of the 
method referred to consists in using for the extraction of the 
alkaloids a mixture of 88 parts (by weight) of ether, 8 of 
alcohol (92 to 95 per cent.), and 4 of liquid ammonia. Prollius 
directs 10 grammes of this liquid to be taken for every gramme 
of bark, but De Vrij recommends the proportion of menstruum 
to be doubled. 10 grammes of finely-powdered bark are intro- 
duced into a well-closed bottle, and, after being carefully tared, 
200 grammes of the ethereal liquid are added. The whole is 
now shaken at intervals during one hour (Biel s&jsfour hours), 
this length of time having been ascertained by comparative 
experiments to be sufficient. The bottle is then again weighed, 
. and if evaporation has taken place the necessary quantity of 
ether mixture is added. As much as possible of the clear 
liquid is now poured off into a flask, and the bottle again 
weighed ; the difference in weight gives the amount of solution 
taken. The ether is then recovered by distillation, and the 
residual liquid, containing alkaloid and waxy matter, is trans- 
ferred to a tared porcelain dish and glass rod, the flask being 
washed with a little spirit. The evaporation is now continued 
on the water-bath until the weight is constant. This gives the 
amount of crude alkaloid. For instance, 10 grammes of succi- 
rubra-bark were digested with 200 grammes of ethereal liquid : 
159.8 grammes of the clear solution gave a residue of 0.78 
gramme, or 9.76 per cent, of crude alkaloid. 

To estimate the pure alkaloids, the crude residue is dissolved 
in dilute hydrochloric acid, filtered, washed as long as the 
washings precipitate with solution of soda, and the whole made 
alkaline and shaken with chloroform. After standing twelve 
hours the clear chloroformic solution is van into a flask and 
evaporated by distillation. The residue is transferred with a 
little spirit to a tared dish and stirrer, and heated on the water- 
bath till the weight is constant. Particular attention should 



676 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

be paid to the latter point. In the instance referred to 0.648 
gramme of alkaloid was obtained, equivalent to 8.11 per cent., 
or about 1J per cent, less than the amount of crude alkaloid. 
By estimating the crude alkaloid and deducting 1J per cent., 
a result will be arrived at, with loss of but little time, which, 
for the practical purposes of the pharmacist, will be sufficiently 
near the truth. 

Official (_B. P.) Methods for Testing Sulphate of Quinine for 
Sulphates of Other Alkaloids. 

Test for Cinchonidine and Cinchonine. — Heat one hundred 
grains of sulphate of quinine in five or six ounces of boiling 
water, with three or four drops of diluted sulphuric acid. Set 
the solution aside until cold. Separate, by filtration, the puri- 
fied sulphate of quinine which has crystallized out. To the 
filtrate, which should nearly fill a bottle or flask, add ether, 
shaking occasionally, until a distinct layer of ether remains 
undissolved. Add ammonia in very slight excess, and shake 
thoroughly, so that the quinine at first precipitated shall be 
redissolved. Set aside for some hours or during a night. Re- 
move the supernatant clear ethereal fluid, which should occupy 
the neck of the vessel, by a pipette. Wash the residual aque- 
ous fluid and any separated crystals of alkaloid with a very lit- 
tle more ether, once or twice. Collect the separated alkaloid 
on a tared filter, wash it with a little ether, dry at 212° F. 
(100° C), and weigh. Four parts of such alkaloid correspond 
to five parts of crystallized sulphate of cinchonidine or of sul- 
phate of cinchonine. 

Test for Quinidine. — Recrystallize fifty grains of the original 
sulphate of quinine as described in the previous paragraph. To 
the filtrate add solution of iodide of potassium and a little spirit 
of wine to prevent the precipitation of amorphous hydriodates. 
Collect any separated hydriodate of quinidine, wash with a little 
water, dry, and weigh. The weight represents about an equal 
weight of crystallized sulphate of quinidine. 

Test for Cupreine. — Shake the recrystallized sulphate of 
quinine, obtained in testing the original sulphate of quinine for 
cinchonidine and cinchonine, with one fluidounce of ether and 
a quarter of an ounce of solution of ammonia, and to this ethe- 
real solution, separated, add the ethereal fluid and washings also 
obtained in testing the original sulphate for the two alkaloids 
just mentioned. Shake this ethereal liquor with a quarter of a 
fluidounce of a 10 per cent, solution of caustic soda, adding water 
if any solid matter separates. Remove the ethereal solution. 



QUININE, 677 

Wash the aqueous solution with more ether, and remove the 
ethereal washings. Add diluted sulphuric acid to the aqueous 
fluid heated to boiling until the soda is exactly neutralized. 
When cold collect any sulphate of cupreine that has crystal- 
lized out on a tared filter ; dry and weigh. 

" Sulphate of quinine " should not contain much more than 
5 per cent, of sulphates of other cinchona alkaloids. 

Sulphate of quinine normally contains 14.45 per cent, of 
water; sulphate of cinchonidine, 13.17 per cent. — all given off 
at 100° to 115° C. The drying should therefore be effected at 
100° C, and the dried salt weighed in well-fitting weighing- 
tubes. 100 parts of cinchonidine are equivalent to 116 parts 
of sulphate of cinchonidine. 

Sulphate of cinchonidine is almost the only salt likely to 
be accidentally present in the sulphate of quinine of trade, 
much quinidine being rarely present in bark, and sulphate of 
cmchonine being sufficiently soluble to always remain in the 
mother-liquors of sulphate of quinine. The sulphate of cin- 
chonidine may vary from 1 to 12 per cent., but more usually 
is present to the extent of about 6 per cent. 

Qidnina, U. S. P. : " If 1 gm. of quinine be mixed, in a 
mortar, with 0.5 gm. of sulphate of ammonium and 5 c.c. of 
distilled water, the mixture thoroughly dried on the water-bath, 
the residue (which should be neutral to test-paper) agitated 
with 10 c.c. of distilled water, this mixture macerated at 15° C. 
(59° F.) for half an hour, then filtered through a small filter, 
5 c.c. of the filtrate taken in a test-tube, and 7 c.c. of water of 
ammonia (sp. gr. 0.960) then added, — on closing the test-tube 
with the finger and gently turning it until the ammonia is fully 
intermixed, a clear liquid should be obtained. If the tempera- 
ture of maceration has been 16° C. (60.8° F.), 7.5 c c. of the 
water of ammonia may be added; if 17° C. (62.6° F.), 8 c.c. 
may be added. In each instance a clear liquid indicates the 
absence of more than about 1 per cent, of cinchonidine and 
quinidine, and of more than traces of cinchonine." 

Quininse Sulphas, U. S. P. : " If 1 gm. of the salt be placed 
in a porcelain capsule, and dried at a temperature of 100° C. 
(212° F.) for three hours, or until a constant weight is attained, 
the remainder, cooled in a desiccator, should weigh not less than 
0.838 gm. (abs. of more than 8 molecules, or 16. IS per cent., 
of water). If the residue thus dried at 100° 0. (212° P.) be 
agitated with 10 c.c. of distilled water, the mixture macerated 
at 15° C. (59° F.) for half an hour, then filtered through a 
small filter, 5 c.c. of the filtrate taken in a test-tube, and 7 c.c. 
of water of ammonia (sp. gr. 0.960) then added, — upon treat- 



678 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

ing this liquid as described above for Quinina the results there 
given should be obtained." 

Of the Citrate of Iron and Quinine (Ferri et Quinine Citras, 
B. P. and U. S. P.) it is officially (B. P.) stated that "50 
grains dissolved in a fluidounce of water and treated with a 
slight excess of ammonia give a white precipitate, which, when 
dissolved by successive treatments of the fluid with ether or 
chloroform, and the latter evaporated and the residue dried (at 
about 250° F.) until it ceases to lose weight, weighs seven and 
a half grains. The precipitate is almost entirely soluble in a 
little pure ether. The British preparation should thus yield 15 
per cent., and that of the United States 12 per cent., of 
quinine. 

A Process for the Determination of the Quinine of the Scaled 
Compound. — A weighed quantity of the scale, about 4 grammes, 
is dissolved in about 50 c.c. of water, and the whole is placed 
in a closed separating-funnel. About the same volume of 
chloroform is added, and enough ammonia to impart a dis- 
tinctly alkaline reaction. The whole is well agitated, and is 
allowed to stand until the two layers separate. The chloro- 
formic layer is then run into a weighed dish. The aqueous 
solution is treated in this way with two more portions of chlo- 
roform, about 25 c.c. each. The mixed chloroformic solutions 
are then evaporated to dryness over a water-bath, and the 
weight of the residue determined. To the residue is added 
about 25 c. c. of water and enough dilute sulphuric acid to 
impart a decidedly acid reaction. The mixture is next heated 
over a water-bath until, the solution remaining acid, the residue 
has completely dissolved. Dilute soda solution is afterward 
added with great care until the solution is exactly neutral. 
The dish is then removed, and the solution allowed to cool and 
rest over night, when the quinine will have separated in crys- 
tals of ordinary sulphate. These should be collected on a 
filter, and the mother-liquor tested with litmus-paper. If it 
is acid, it must be warmed over a water-bath, and dilute soda 
solution added to exact neutralization, and the solution set 
aside as before, when some more crystals will probably sepa- 
rate. These are also collected, and with the former ones 
washed, dried at 100° C, and weighed [(C 20 H 24 N,O 2 ) 2 ,H 2 SO 4 = 
746]. To this weight must be added 1 gramme for every 750 
c.c. of mother-liquor for quinine sulphate which it retains. 
From this weight of anhydrous quinine sulphate is calculated 
its equivalent of hydrous quinine (C 20 H 2i N 2 O 2 ) 2 ,2H 2 O = 684, 
the approximate formula of hydrous quinine dried over a water- 
bath. The weight thus obtained is compared with the weight 



MORPHINE OR MORPHIA. 679 

of total alkaloid determined, both having been reduced to per- 
centages. The amount of hydrous quinine calculated from the 
crystals of sulphate should not be much below that weighed 
directly. In good specimens the difference will be about 1 
per cent. (See also a paper by Fletcher in the Pharmaceutical 
Journal for Sept. 20, 1879; also in that for Sept. 18, 1880, by 
De Vrij ; and in the Chemist and Druggist for Oct., 1885, by 
Howard.) 

MORPHINE OE MO&PHIA. 

The official (U. S. P.) process for the assay of opium is con- 
ducted in the following manner : — 

Grammes. 

Opium, in any condition to be valued, .... 7 

Lime, freshly slaked, 3 

Chloride of Ammonium, 3 

Alcohol, 

Stronger Ether, 

Distilled Water, each a sufficient quantity. 

" Triturate together the opium, lime, and 20 c.c. of distilled 
water in a mortar until a uniform mixture results ; then add 
50 c.c. of distilled water, and stir occasionally during half an 
hour. Filter the mixture through a plaited filter three to 
three and one-half inches (75 to 90 millimetres) in diameter 
into a wide-mouthed bottle or stoppered flask (having the 
capacity of about 120 c.c. and marked at exactly 50 c.c), until 
the filtrate reaches this mark. To the filtered liquid (repre- 
senting 5 grammes of opium) add 5 c.c. of alcohol and 25 c.c. 
of stronger ether, and shake the mixture ; then add the chlo- 
ride of ammonium, shake well and frequently during half an 
hour, and set it aside for twelve hours. Counterbalance two 
small filters ; place one within the other in a small funnel, and 
decant the ethereal layer as completely as practicable upon the 
filter. Add 10 c.c. of stronger ether to the contents of the 
bottle and rotate it; again decant the ethereal layer upon the 
filter, and afterward wash the latter with 5 c.c. of stronger 
ether, added slowly and in portions. Now let the filter dry in 
the air, and pour upon .it the liquid in the bottle, in portions, 
in such a way as to transfer the greater portion of the crys- 
tals to the filter. Wash the bottle, and transfer the remaining 
crystals to the filter, with several small portions of distilled 
water, using not much more than 10 e.e. in all, and distrib- 
uting the portions evenly upon the filter. Allow tin 1 filter to 
drain, and dry it, first by pressing it between sheets of bihu- 



680 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

lous paper, and afterward at a temperature between 55° and 
60° C. (131° to 140° F.). Weigh the crystals in the inner 
filter, counterbalancing by the outer filter. The weight of the 
crystals in grammes, multiplied by twenty, equals the- percent- 
age of morphine in the opium taken." [At 110° C. morphine 
is anhydrous.] 

"On exhausting 100 parts of opium previously dried 
at a temperature of 105° C. (221° F.), with cold water, 
and evaporating the solution to dryness, an extract is 
obtained which should weiah between 55 and 60 parts." — 
IT. S. P. 

The foregoing process yields results almost exactly compara- 
ble amongst themselves ; therefore is medically reliable. It 
has been generally recognized as involving some loss of mor- 
phine, the loss being, however, fairly constant. Messrs. Tesche- 
macher and Smith, after working for many years on the sub- 
ject, have devised such a combination of known morphio- 
metric methods as to enable them to obtain more morphine from 
a given sample of opium than they formerly obtained, and 
about 2 or 2\ per cent, more morphine from a given sample 
than they can obtain by the official method. They hope to so 
extend their improvements as to obtain still higher results. 
Meanwhile, they claim for their method not only the important 
medical desideration that like other trustworthy methods it 
yields constant results, but that it necessarily yields results at all 
events nearer to truth than the results hitherto obtained. The 
minimum contents by the official process is to be 9 per cent, of 
morphine or 10.3 from the dried opium. This corresponds to a 
yield by the annexed process of 12J per cent, from dried 
opium. 

Teschemacher and Smith's Method. — Thoroughly exhaust 200 
grains of opium with warm distilled water. Concentrate this 
water extract to a thin syrup in a shallow dish, over a water- 
bath, the water of which should not quite boil. Trans- 
fer this thin syrup to a suitable flask, which permits the use of 
a soft cork, using a few drops of water successively to wash out 
the dish. Add to the contents of the flask 50 fluidgrains of 
alcohol, sp. gr. about 0.820, and about 600 fluidgrains of ether. 
Mix gently, but thoroughly, and then add some 50 fluidgrains 
of ammonia, sp. gr. 0.935. Shake the contents of the flask 
well to precipitate the alkaloids in arenaceous crystals, with 
occasional agitation during the ensuing eighteen hours. Trans- 
fer the contents of the flask to a vacuum filter, and permit all 
the adherent liquid to be drawn away, washing out the flask 



SUGAR. 681 

■with morphinated spirit* and continue its use till the liquid 
passes colorless. Then wash the morphinated water f till this 
also passes colorless. Now dry, slowly at first, finishing at 
212° F. Transfer the dried substance to a mortar, reduce it to 
a very fine powder, and digest it thoroughly in benzene to dis- 
solve the narcotine and such of the opium alkaloids, other than 
morphine, which may be present. Transfer this mixture to a 
vacuum filter, wash out the mortar carefully with benzene, 
which use to wash the powder thoroughly. This, then, will be 
morphine, free from other opium alkaloids and narcotine, but 
still containing coloring and possibly other organic matters to 
the extent of 3 to 10 per cent. Dry and weigh this powder. 
Now ascertain the percentage of crystallized morphine by titra- 
tion of this powder with standard hydrochloric acid and litmus 
as the indicator, by weight. This acid is so made that 1000 
grains by weight shall exactly neutralize 100 grains of pure 
morphine crystallized from water, washed with ether, and 
gently dried finally at 212° F. 

SUGAR. 

The qualitative test of sugar by means of an alkaline copper 
solution (vide p. 470) may be applied in the estimation of sugar 
in sacchariferous substances. 
f K Process 1. — 34.65 grammes of pure dry crystals of ordinary 
( H' sulphate of copper are dissolved in about 250 c.c. of distilled 
water, and 173 grammes of pure crystals of the double tartrate 
of potassium and sodium are dissolved in 480 c.c. of solution of 
caustic soda of sp. gr. 1.14. The solutions are only mixed when 
required, water being then added to form one litre, smaller quan- 
tities of the fluids being proportionately diluted. 100 c.c. of 
this solution represent 3.464 grammes of sulphate of copper, 
and correspond to 0.5 of a gramme of pure anhydrous grape- 
sugar, 0.475 of cane-sugar, 0.82 of maltose, or 0.45 of starch. 
The solutions must be preserved in a well-stoppered bottle to 
prevent absorption of carbonic acid, and be kept in a dark 
place. Should the mixture give a precipitate on boiling, a 
little solution of soda may be added when making experiments. 
A solution of this strength is officially (U. S. P.) termed " Test- 
Solution of Potassio-cupric Tartrate," or " Folding's Solution." 

* For Morphinated Spirit. — Digest a large excess of morphine in recti- 
fied spirit of 80 per cent., for several days, with frequent agitation ; fil- 
ter for use. 

f For Morphinated Water. — As above, substituting distilled water for 
spirit. 



■v- 



682 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

Dissolve 0.475 of pure dry powdered cane-sugar in about 50 
c.c. of water, convert into grape-sugar by acidulating with sul- 
phuric acid and heating for an hour or two on a water-bath, 
make slightly alkaline with carbonate of sodium, and dilute to 
100 c.c. Place 10 c.c. of the copper solution in a small flask, 
dilute with three or four times its bulk of water, and gently 
boil. Into the boiling liquid drop the solution of sugar from 
a burette, one cubic centimetre or less at a time, until, after 
standing for the precipitate to subside, the supernatant liquid 
has just lost its blue color; 10 c.c. of the solution of the 
sugar should be required to produce this effect = 0.0475 of 
cane-sugar, 0.082 of maltose, or 0.05 of grape-sugar. Experi- 
ments on pure cane-sugar must be practised until accuracy is 
attained ; syrups, diabetic urine, and saccharated substances 
containing unknown quantities of sugar may then be analyzed. 

Starch is converted into grape-sugar by gentle ebullition 
with dilute acid for eight or ten hours, the solution being 
finally diluted so that one part of starch, or rather sugar, 
shall be contained in about 150 of water. 

If instead of Fehling's Solution, Pavy's Ammoniated Solu- 
tion be used (Proceedings of the Royal Society of London, vol. 
xxviii., p. 260, and vol. xxix., p. 272), one-fifth more of the 
copper salt will be required to do the same amount of work. 

In cases in which loss of blue color cannot be relied on as 
indicating the termination of the reaction, the suboxide of 
copper should be rapidly filtered out, washed, dried, and, after 
adding the filter ash, ignited, and the resulting black oxide of 
copper weighed. One gramme of black oxide (or of suboxide 
or of metallic copper) indicates the subjoined amounts of the 
respective sugars: — 

Cue gramme of — Glucose. Cane-sugar. Milk-sugar. Malt-sugar. 

Black oxide 4535 .4308 .6153 .7314 

Suboxide . . . . . . .5042 .4790 .6843 .8132 

Metallic copper . . . .56.34 .5395 .7707 .9089 

Process 2. — Roberts Method for the Estimation of Sugar in 
Urine. — About four ounces of saccharine urine are put into a 
twelve-ounce bottle, and a lump of German yeast about the 
size of a cob-nut or small walnut is added. This excess of 
yeast hastens fermentation, and does no harm. The bottle is 
then covered with a grooved cork (to allow of the escape of 
carbonic acid gas) and set aside in a warm place to ferment. 
By the side of it is placed a tightly corked four-ounce phial 
filled with the same urine without any yeast. In about twenty- 
four hours the fermentation will have ceased and the scum 
cleared off or subsided. The fermented urine is then decanted 



683 



and its specific gravity taken. At the same time the specific 
gravity of the unfermented urine in the companion phial is 
observed. The density lost is thus ascertained. Each degree 
of density lost represents a grain of glucose per fluidounce. 

Sugar is often estimated by the measurement of the car- 
bonic acid gas evolved during fermentation. 

Saccharimetry. — A generic term for certain volumetric oper- 
ations undertaken with the view of ascertaining the quantity 
of sugar present in any matter in which it may be contained. 

Saccharimetry is frequently performed upon common syrup 
{Syrupus, B. P.) and solutions which are known to contain 
nothing but cane- (ordinary) sugar, the object being merely to 
ascertain the amount present. In such a case it is only neces- 
sary to take the specific gravity of the liquid at 60° F., and 
then refer to a previously prepared Table of density and per- 
centages : — 



Specific 
gravity. 

1.007 
1.014 
1.022 
1.029 
1.036 
1.044 
1.052 
1.060 
1.067 
1.075 
1.083 
1.091 



Sugar, 
per cent. 

1.8 
3.5 
5.2 

7.0 

8.4 
10.4 
12.4 
14.4 
16.3 
18.2 
20.0 
21.8 



Specific 


Sugar, 


Specific 


Sugar, 


gravity. 


per cent. 


gravity. 


per cent. 


1.100 . 


. 23.7 


1.210 . 


. 46.2 


1.108 . 


. 25.6 


1.221 . 


. 48.1 


1.116 . 


. 27.6 


1.231 . 


. 50.0 


1.125 . 


. 29.4 


1.242 . 


. 52.1 


1.134 . 


. 31.5 


1.252 . 


. 54.1 


1.143 . 


. 33.4 


1.261 . 


. 56.0 


1.152 . 


. 35.2 


1.275 . 


. 58.0 


1.161 . 


. 37.0 


1.286 . 


. 60.1 


1.171 . 


. 38.8 


1.289 . 


. 62.2 


1.180 . 


. 40.6 


1.309 . 


. 64.4 


1.190 . 


. 42.4 


1.321 . 


. m.(ii 


1.199 . 


. 44.3 


1.330 (b. 


p.) 66.6? 



The sp. gr. may be taken by a hydrometer, technically 
termed a saccharometer. (The above spec, gravs. = 1° to 35° 
Baume.) 

If a liquid contains other substances besides cane-sugar, the 
test of specific gravity is of little or no value. Advantage 
may then be taken of the fact that syrup causes right-handed 
twisting of a ray of polarized light to an extent exactly pro- 
portionate to the amount of sugar in solution. The saccharine 
fluid is placed in along tube having opaque sides and trans- 
parent ends, and a ray of homogeneous light, polarized by re- 
flection from a black-glass mirror or otherwise, is sent through 
the liquid and optically examined by a plate of tourmaline, 
Nicol's prism, or other polarizing eye-piece. Attached to the 
eye-piece is a short arm which traverses a circle divided into 



684 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

degrees. The eye-piece and arm are previously so adjusted 
that when the ray is no longer visible the arm points to the 
zero of the scale of degrees. The saccharine solution, how- 
ever, so twists the ray as to again render it visible ; and the 
number of degrees which the eye-piece has to be rotated before 
the ray is once more invisible is exactly proportionate to the 
strength of the solution. The value of the degrees having 
been ascertained by direct experiment and" the results tabulated, 
a reference to the Table at once indicates the percentage of. 
sugar in the liquid under examination. Grrape-sugar also pos- 
sesses the property of dextrorotation, but less powerfully 
than cane-sugar ; moreover, the former variety does not, like 
cane-sugar, suffer inversion of the direction of rotation on the 
addition of hydrochloric acid to its solution — an operation that 
furnishes data for ascertaining the amounts of cane- and of 
grape-sugar, or of crystallizable and non-crystallizable sugar, 
present in a mixture. In using the polariscope-saccharometer 
it is convenient to employ tubes of uniform size and always to 
operate at the same temperature. Various modes are adopted 
of applying, for the purposes of quantitative analysis, the ac- 
tion of syrup on polarized light. 



ALCOHOL. 

Mulder s process for the determination of the amount of 
alcohol in wines, beer, tinctures, and other alcoholic liquids 
containing vegetable matter is as follows : — Take the specific 
gravity and temperature of the liquid, and measure off a certain 
quantity (100 cubic centimetres) ; evaporate to one -half or less, 
avoiding ebullition in order that particles of the material may 
not be carried away by the steam. Dilute with water to the 
original bulk, and take the specific gravity at the same tempe- 
rature as before. Of the figures representing this latter spe- 
cific gravity, all over 1.000 show to what extent dissolved solid 
matter affected the original specific gravity of the liquid. Thus, 
the specific gravity of a sample of wine at 15°. 5 C. is 0.9951 ; 
evaporated till all alcohol is removed and diluted with water to 
the original bulk, the specific gravity at 15°. 5 C. is 1.0081 ; 
0.0081 represents the gravitating effect of dissolved solid mat- 
ter in 0.9951 parts of original wine. 0.0081 subtracted from 
0.9951 leaves 0.987, which is the specific gravity of the water 
and alcohol of the wine. Or divide the sp. gr. of the wine by 
the sp. gr. of the wine minus alcohol, carrying out the sum to 
four places of decimals ; the quotient shows the sp. gr. of the 



DIALYSIS. 685 

water and alcohol only of the wine. On referring to a Table 
of the strengths of diluted alcohol of different specific gravi- 
ties (p. 659), 0.987 at 15°. 5 C. is found to indicate a spirit 
containing 8 per cent, of real alcohol. Mulder's process is that 
adopted officially (U. S. P.) for ascertaining the strength of 
white wine ( Vinum Alburn) and red wine ( Vinum Rubrum). 
If the foregoing operation be conducted in a retort, the liquid 
being boiled and the steam carefully condensed, the distillate, 
diluted with water to the original bulk of wine operated on, 
will still more accurately represent the amount of water and 
alcohol in the wine, its specific gravity showing the percentage 
of real alcohol present. 

DIALYSIS. 

Dialysis (from did, dia, through, and Xbmc;, lusis, a loosing 
or resolving) is a term applied by Graham to a process of 
analysis by diffusion through a septum. The apparatus used 
in the process is called a dialyzer, and is constructed and em- 
ployed in the following manner. The most convenient septum 
is the commercial article known as parchment-paper, made by 
immersing unsized paper for a short time in sulphuric acid ; it 
is sold by most dealers in chemical apparatus. A piece of this 
material is stretched over a gutta-percha hoop and secured by 
a second external hoop. Dialyzers of useful size are one or 
two inches deep and five to ten inches wide. Liquids to be 
dialyzed are poured into the dialyzer, which is then floated in a 
flat dish containing distilled water. The portion passing 
through the septum is termed the diffusate ; the portion which 
does not pass through is termed the dialysate. 

The practical value of dialysis depends upon the fact that 
certain substances will diffuse through a given septum far more 
readily than others. Uncrystallizable bodies diffuse very slowly. 
Of such matters as starch, gum, albumen, and gelatin, the hist 
named is perhaps least diffusive ; hence substances of this class 
are termed colloids, or bodies like collin, which is the soluble 
form of gelatin. Substances which diffuse rapidly are most, 
crystalline ; hence bodies of this class are termed crystalloids. 

Dialyzed iron, an aqueous solution of about 5 per cent, of 

highly basic oxychloride of iron, is obtained by saturating solu- 
tion of perchloride of iron with ferric hydrate, by adding am- 
monia, or, better, carbonate of sodium, and shaking vigorously 
until the precipitated hydrate ceases to undissolve, filtering it' 
necessary, placing on a dialyzer floating in distilled water, and 
displacing the fluid in the dish by water daily for a week or 
58 



686 QUESTIONS AND EXERCISES. 

two, or until the diffusate gives no reaction with nitrate of 
silver. The crystalloids (chloride of sodium or other salt) pass 
through the dialyzer ; the colloid fluid which does not pass 
through the dialyzer is the highly basic oxy chloride of iron, or 
so-called " dialyzed iron" or " dialytic iron." This fluid has 
very little taste of iron. Its value as a medicine has been 
questioned, its non-diflusibility suggesting that it never passes 
out of the intestinal canal, and therefore never gets into the 
blood. 

The phenomena of dialysis show that crystalloids are superior 
to colloids in affinity for water. 



QUESTIONS AND EXERCISES. 

1068. Carbonate of potassium is said to lose 16 per cent, of water 
on exposure to a red heat ; give the details of manipulation observed 
in verifying this statement. 

1069. Write a few paragraphs descriptive of the process of ulti- 
mate organic analysis. 

1070. In what forms are carbon, hydrogen, and nitrogen weighed 
in quantitative analysis? 

1071. In the combustion of .41 of a gramme of sugar, what weights 
of products will be obtained? Ans. .632 of carbonic acid gas (C0 2 ) 
and .237 of water (H 2 0). 

1072. IIow is cinchona assayed for mixed alkaloids? 

1073. On what facts does De Vrij found his method for the separa- 
tion and quantitative determination of all the cinchona alkaloids? 

1074. Describe De Vrij"s process for the assay of commercial sul- 
phate of quinine. 

1075. Give the official method for the estimation of morphine in 
opium. 

1076. Mention the operation necessary for the estimation of the 
proportion of sugar in saccharated carbonate of iron or in a speci- 
men of diabetic urine. 

1077. What is understood by Saccharimefry ? 

1078. Give two processes for the estimation of the percentage of 
alcohol in tinctures, wines, or beer. 

1079. Define dialysis. 



Conclusion. 



Detailed instructions for the quantitative analysis of potable 
water, articles of food, general technical products, special 
minerals, soils, manures, air, illuminating agents (including 
solid fats, oils, spirits, petroleum, and gas), dyes, and tanning- 
materials would scarcely be in place in this volume. 

The course through which the reader has been conducted 



CONCLUSION. 687 

will, it is hoped, have taught the principles of the science of 
Chemistry, and given special knowledge concerning the appli- 
cations of that science to medicine and pharmacy, as well as 
have imparted sufficient manipulative skill to meet the require- 
ments of manufacture or analysis. The author would venture 
to suggest that this knowledge be utilized, not only in the way 
of personal advantage, but in experimental researches on chem- 
ical subjects connected with therapeutics and pharmacy. The 
discovery and publication of a new truth, great or small, is the 
best means whereby to aid in advancing the calling in which 
we may be engaged, increase our own reputation, and contrib- 
ute to that ultimate end of knowledge " which Bacon defined 
as " employing the divine gift of reason to the use and benefit 
of mankind." 



APPENDIX. 



TABLE OF TESTS FOE IMPUEITIES IN PEEPAEATIONS 
OF THE UNITED STATES PHAEMACOPCEIA * 



Name of Preparation 



Acidum Aceticu 



Acid. Acetic. Gla- 
ciale, 



Acidum Boricum, 



Acidum Carboli- f 

cum, ( 

Acidum Chromi- f 



Impurities. 



Starch. 

Copper, Lead, or Tin. 

Iron. 

Calcium. 

Other mineral matter. 

Empyreumatic sub- 
stances. 

Organic matter. 
Nitric Acid. 

Sulphuric Acid. 
Hydrochloric Acid. 

Sulphurous Acid. \ 

Sulphurous Acid. 

Sulphuric Acid. 

Hydrochloric Acid. 

Lead, Copper, Iron, 

etc. 
Calcium. 
Sodium Salts. 
Chlorobenzoic Acid. 

Cinnamic Acid. 

Other organic matter. 

Creasote and Cresylic 
Acid. 

More than trace of Sul- 
phuric Acid. 



Iodine. 

Sulphuretted Hydrogen. 

Excess of Ammonia. 

Oxalate of Ammonium. 

Evaporation and ignition 

Color and odor with Pot- 
ash. 

Reduction by Permanga- 
nate of Potassium. 

Sulphuric Acid. 

Sulphuric Acid and Sul- 
phate of Iron. 

Chloride of Barium. 

Nitrate of Silver. 

Nascent Hydrogen. 

Nitrate of Silver. 

Nascent Hydrogen, or Ni- 
trate of Silver. 

Chloride or Nitrate of Ba- 
rium. 

Nitrate of Silver and Ni- 
tric Acid. 

Sulphide of Ammonium. 

Oxalate of Ammonium. 

In flame on Pt. wire. 

Cupric Oxide and flame- 
test. 

Permanganate of Potas- 
sium and water. 

Odor: warm Sulphuric 
Acid. 

Glycerin, and dilution, 
oxidation, etc. 

Chloride of Barium. 



* The manipulations necessary to be observed in testing for impurities will be 
found described in the paragraphs treating of those- substance's. The Table also 
includes references to processes for ascertaining deficiency in strength of official 
articles. 

The other characters and tests of pharniacopa>ial chemical compounds have been 
given in connection with the respective synthetical and analytical reactions. 
58* 689 



690 



APPENDIX. 

Table of Tests — Continued. 



Name of Preparation. 



Acidum Citric urn, ■ 



Acidum Gcdlicum, 

Acidum Hydrobro- 
mic. Dilut.. 



Acidum Hydro- 
chloricum. 



Acid. Hydrocyan- 
icum, Dil., 



Acidum Lacticum, 



Impurities. 



Acidum Nitricum, * 



Acidum Oleicum, 
Acidum Phosphor 



Tartaric and Oxalic 

Acids. 
Tartaric Acid. 
Lead or Copper. 
Sulphuric Acid. 

Mineral matter. 
Tannic Acid. 

Sulphuric Acid. 

Sulphuric Acid. 

Sulphurous Acid. 
(Arsenic. 
I 
iLead, Iron, or Copper. 

I 
Free Chlorine. 

Sulphuric Acid. 

Hydrochloric Acid. 

Hydrochloric Acid. 
Sulphuric Acid. 

Sarcolactic Acid. 
Lead or Iron. 

Sugars. 
Glycerin. 

Other organic matter. 
Iron or Lead. 

Copper. 
Mineral matter. 

Arsenic Acid. 

Sulphuric Acid. 

Hydrochloric Acid. 
Free Iodine. 
Iodic Acid. 

Palmitic and Stearic 
Acids. 

Fixed Oils. 
Phosphorous Acid. 



Acetate of Potassium and 
Alcohol. 

Bichromate of Potassium. 

Sulphuretted Hydrogen. 

Chloride or Nitrate of Ba- 
rium. 

Incineration. 

Gelatin, Alkaloidal Salts, 
Tartarated Ant'ny, etc. 

Chloride or Nitrate of * 
Barium. 

Chloride or Nitrate of 
Barium. 

Nascent Hydrogen. 

Sulphuretted Hydrogen ; 
Copper. 

Sulphydrate of Ammo- 
nium. 

Iodide of Potassium. 

Chloride or Nitrate of 
Barium. 

Ppt. by Nitrate of Silver ; 
insol. in Nitric Acid. 

Nitrate of Silver. 

Chloride or Nitrate of 
Barium. 

Sulphate of Copper. 

Ammonia and Sulphy- 
drate of Ammonium. 

Potassio-cupric Tartrate. 

Hydrate of Zinc and Ab- 
solute Alcohol. 

Cold Sulphuric Acid. 

Ammonia and Sulphy- 
drate of Ammonium. 

Excess of Ammonia. 

Evaporation and gent 
ignition. 

Excess of Potash, boil 
with, Zinc. 

Chloride or Nitrate of 
Barium. 

Nitrate of Silver. 

Mucilage of Starch. 

Starch and Sulphuretted 
Hydrogen. 

Saponification, Acetic 
Acid, and Acetate of 
Lead. 

Alcohol. 

Nitrate of Silver; Mercu- 
ric Chloride. 

Sulphuretted Hydrogen. 



APPENDIX. 691 

Table of Tests — Continued. 



Name of Preparation, 



Acidum Phosphor- 
icum, 



Acidum Salicyl- 
icum, 



Acidum Sulphuri- 
cum, 



Acidum Sulphur o- 

sum, (^ 

Acidum Tdnniatm, 

Acidum Tartar- J 
icum, 

l 
f 

Adeps, ■{ 

JEiher, j 

JEthcr Aceticus, <j 

jEtJicr Fortior < 



Alcohol, 



Impurities. 



Nitric Acid. 

Sulphuric Acid. 

Hydrochloric Acid. 

Pyro- or Meta-phos 

phoric Acid. 
Hydrochloric Acid. 

Organic matter and 

Iron. 
Organic matter. 
Carbolic Acid. 



Lead. 
Nitric Acid. 

Hydrochloric Acid. 

Lead, Arsenic, or Cop- 
per. 

Iron. 

Mineral matter. 

Arsenious or Sulphur- 
ous Acid. 

Much Sulphuric Acid. 

Mineral matter. 
Lead or Copper. 
Iron. 

Sulphuric Acid. 
Mineral matter (more 

than trace). 
Alkalies. 
Starch (flour). 
Chloride (of Sodium). 
Excess of water. 
Mineral matter. 

Mineral matter. 

Acetic Acid. 

Water. 

Alcohol. 

Acid. 

Excess of water and 

Alcohol. 
Fusel Oil. 
Amylic Alcohol. 
Methyl Alcohol. 
Aldehyd and Oal 

Tannin. 



Tests. 



Sulphuric Acid and Fer- 
rous Sulphate. 

Chloride or Nitrate of 
Barium. 

Nitrate of Silver and Ni- 
tric Acid. 

Tincture of Chloride of 
Iron, Albumen. 

Nitrate of Silver and Ni 
trie Acid. 

Crystallization from Alco 
hoi (white). 

Cold Sulphuric Acid. 

Chlorate of Potassium, 
Hydrochloric Acid, and 
Ammonia. 

Alcohol. 

Solution of Ferrous Sul 
phate. 

Sulphate of Silver. 

Sulphuretted Hydrogen. 

Excess of Ammonia. 
Incineration. 
Nascent Hydrogen. 

Chloride of Barium. 

Incineration. 
Sulphuretted Hydrogen. 
Ammonia and Sulphy- 

drate of Ammonium. 
Chloride of Barium. 
Incineration. 

Litmus. 

Iodine. 

Nitrate of Silver. 

Drying on water-bath. 

Evaporation. (See also 

JEther Fortior.) 
Evaporation. 
Test-papers. 
Specific gravity. 
Boiling-point. 
Test-papers. 
Agitation with Glycerin; 

boiling-point. 
Water and Glycerin. 
Sulphuric Acid. 

Solution of Potash. 



692 



APPENDIX. 
Table of Tests— Continued. 



Name of Preparation 



Alcohol Absolu- 
tion, 



Aluminii Hydras, 



Aluminii Sulphas, 
Ammonii Benzoas, 



Ammonii Bromi- 
dum, 



Ammonii Carbo- 



Ammonii Chlori- 



Ammonti Iodidum, 



Impurities. 



Methyl Alcohol. 

Fixed residue or resin 
Water. 

Ammonia Alum. 
Zinc or Lead. 

More than trace of 

Iron. 
Iron. 

Sulphuric Acid. 

Zinc or Lead. 

Alkaline Salts (more 

than trace). 
Iron. 

Fixed Salts. 

Bromate (of Ammo- 
nium). 

Iodide (of Ammo- 
nium). 

Sulphate (of Ammo- 
nium). 

More than 3 per cent, 
of Chloride. 

Sulphate (of Ammo- 
nium). 

Chloride (of Ammo- 
nium). 

Metals, 
mpyreumatic sub- 
stances. 

Barium. 

Metals. 



Sulphate (of Ammo- 
nium). 
Iron. 

Sulphate (of Ammo- 
nium). 

Chloride and Bromide 
(excessive). 



Carbonate of Lead and 
Permanganate. 

Evaporation. 

Sulphate of Copper (an- 
hydrous). 

Potash or Soda. 

Sulphydrate of Ammo- 
nium in alkaline filtrate. 

Ferrocyanide of Potas- 
sium. 

Ferrocyanide of Potas- 
sium. 

Chloride or Nitrate of 
Barium. 

Sulphydrate of Ammo- 
nium. 

Solution in water and 
evaporation. 

Ferrocyanide of Potas- 
sium. 

Incineration. (See also 
Acidum Benzoicum.) 

Diluted Sulphuric Acid. 

Chlorine-water and muc 

lage of Starch. 
Chloride or Nitrate of 

Barium. 
Quantitative Analysis. 

Chloride or Nitrate of 

Barium. 
Nitrate of Silver. 

Sulphuretted Hydrogen. 

Excess of Sulphuric Acid 
and Permanganate. 

Sulphuric Acid. 

Sulphuretted Hydrogen or 
Sulphydrate of Ammo- 
nium, 

Nitrate of Barium. 

Ferrocyanide of Potas- 
sium. 

Chloride or Nitrate of 
:arium. 

Ammoniacal solution, Ni- 
trate of Silver, and Ni- 
tric Acid ; and Quantita- 
tive Analysis. 

Ferrocyanide of Potas- 
sium. 



APPENDIX. 

Table or Tests — Continued. 



693 



Name of Preparation 


Impurities. 


Tests. 


Ammonii lodidum, 


Free Iodine. 


Mucilage of Starch. 




Sulphate (of Ammo- 


Chloride or Nitrate of 


Ammonii Nitras, ■ 


nium). 
Chloride (of Ammo- 
nium). 


Barium. 
Nitrate of Silver. 




Metals. 


Sulphuretted Hydrogen or 
Sulphide of Ammonium. 


Ammonii Pkos- 


Sulphate (of Ammo- 


Chloride or Nitrate of 


phas, 


nium). 


Barium. 




Chloride (of Ammo- 


Nitrate of Silver. 




nium). 




f 


Lead or Iron. 


Sulphide of Ammonium. 


Ammonii Sulphas, < 


Chloride (of Ammo- 
nium). 


Nitrate of Silver. 


{ 


Acetate (of Ammo- 


Ferric Chloride. 




nium). 




Ammonii Valeri- J 


Sulphate (of Ammo- 


Nitrate or Chloride of 


anas, 


nium). 


Barium. 




Chloride (of Ammo- 


Nitrate of Silver. 


I 


nium). 




Amyl Nitras } 


Excess of free acid. 


Quantitative Analysis. 




Sulphate (of Potas- 


Chloride of Barium. 




sium). 






Chloride (of Potas- 


Nitrate of Silver. 


Antimonii et Po- 
tassii Tartras, 


sium). 
Iron and other metals. 


Ferrocyanide of Potas- 
sium and Acetic Acid. 


^ 


Calcium. 


Oxalate of Ammonium. 




Arsenic. 


Nascent Hydrogen and 
Nitrate of Silver. 


Antimonii Oxi- f 


Same as Ant. et Pot. 




dum, \ 


Tart., q. v. 




r 


Metallic Sulphides. 


Ignition with Nitrate of 


Antimonii Sulphi- J 




Soda. 


dum Purif., 


Arsenic. 


Ammonio-nitrate of Sil- 


Antimonium Sid- f 


Sulphate (of Sodium). 


Chloridc or Nitrate of 


phuratum, \ 




Barium. 


" 


Metallic impurities. 


Sulphydrate of Ammo- 


Aqua, 




nium. 


Organic matter. 


Permanganate of Potas- 






sium. 




Empyreumatic sub- 


Neutralization with Sul- 




stances. 


phuric Acid and odor: 
also Permanganate. 




Carbonate. 


Lime-water. 


Aqua Ammonite, 


Sulphate. 


Chloride or Nitrato of 
Barium. 




Chloride. 


Nitrate of Silver. 




Metals. 


Sulphuretted Hydrogen. 


{ 


Calcium. 


Oxalate of Ammonium. 


Aqua Aurantii \ 

Fiona,,, } 


Metals (Pt>, Cu, Sn). 


Sulphuretted Hydrogen. 



694 



APPENDIX. 

Table of Tests — Continued. 



Name of Preparation. 



Aqua Destillata, 



Argenti Iodidum, 

Argenti Nitras, \ 

Argenti Oxidum, 
Atrophia, 
Atropine Sulphas, 
Auri et Sodii Ohio- j 

rid urn, J 

Aurum, 
Balsamuni Peruvi- 

anum, 



Benzinum, 



Bismuthi Gitras, j 

Bismuth, et Am- 
nion. Git., 



Bismuthi Subcar- 
bonas, 



Bismuthi 
tras, 

Bromum, 



Impurities. 



Sulphuric radical. 

Hydrochloric radical. 

Calcium. 

Ammonia or its salts. 



Organic matter. 
Chloride (of Silver). 



Metallic impurities. 

Carbonate. 
Mineral matter. 
Mineral matter. 

Free Acid. 

Copper or Silver. 
Volatile Oil. 
Gurjun Balsam. 
Heavy Hydrocarbons 

Pyrogenous prod- 
ucts and Sulphur 
compounds. 

Benzol. 

Nitrate. 

Nitrate. 

Insoluble salts. 

Lead. 

Copper. 

Silver. 

Sulphate. 

Chloride. 

Alkalies and a Ik. 

earths. 
Ammonia. 
Antimony, Arsenic, 

Tin. 
Arsenic. 

Carbonate. 

Insoluble foreign salts. 

Chlorine (excess). 



Sulphuretted Hydrogen or 
Sulphydrate of Ammo- 
nium. 

Chloride or Nitrate of 
Barium. 

Nitrate of Silver. 

Oxalate of Ammonium. 

Tvlercuric Chloride and 
Carbonate of Potassium, 
or Nessler's-Reagent. 

Permanganate of Potas 
sium. 

Boil with Carbonate of 
Ammonium, and add 
Nitrie Acid. 

Hydrochloric Acid and 
evaporation. 

Acid (Hydrochloric). 

Incineration. 

Incineration. 

Ammonia fumes. 

Nitric Acid. 
Distillation with water. 
Bisulphide of Carbon. 
Evaporation at low temp, 
and odor. 

Spirit of Ammonia and 
Nitrate of Silver. 

Sulphuric and Nitric 
Acids. 

Sulphuric Acid and Fer- 
rous Sulphate. 

Sulphuric Acid and Fer- 
rous Sulphate. 

Dilute Nitric Acid. 

Sulphuric Acid. 

Excess of Ammonia. 

Hydrochloric Acid. 

Chloride of Barium. 

Nitrate of Silver. 

Evaporation after remov- 
ing Bismuth. 

Fuuies with Acetic Acid. 

Sulphuretted Hydrogen, 
etc. 

Nascent Hydrogen and 
Nitrate of Silver. 

Nitric Acid. 

Nitric Acid. 

Ammonia and Carbonate 
of Barium. 



APPENDIX. 

Table of Tests— Continued. 



695 



Name of Preparation. 



Bromum, 
Caffeina, 



Calcii Bromidum, - 



Oalcii Carbonas 
Prsecip., 



Calcii Cldoridum , 



Calcii Hypoplios- 
phis, 



Calcii PJwsphas J 
Prsecip. ," 



Calx, 

Cambojia, J 

Carbo Animalis \ 
Purificatus, 

Carh 



Bisitl- f 

( 

Cera Alba, Cera] 
Flava, 



Ccrii Oxalas, 



Impurities. 



Iodine. 

Mineral matter. 
Bromate. 
Iodide. 

Sulphate. 

Chloride. 



Magnesium. 

Magnesium. 

Aluminium, Iron, or 
Phosphate of Cal- 
cium. 

Aluminium, Iron, etc, 

Sulphate (of Calcium) 

Magnesium (more 

than trace). 
Insoluble Calcium 

Salts. 
Soluble Phosphate. 
Sulphate. 

Magnesium. 
Carbonate (of Cal- 
cium). 
Aluminium. 
Excess of Carbonate. 
Silica. 
Starch. 
Bark, Sand, etc. 

Earthy Salts. 

Phosphate (of Cal- 
cium). 

Sulphurous Acid. 

Sulphuretted Hydro- 
gen. 

Soap. 

Eats, Japan Wax, 
Resin. 

Paraffin. 



Didymium. 

Aluminium. 



Carbon a to ( of Ceri urn ) . 
Metallic impurities. 



Gelatinized Starch. 

Incineration. 

Sulphuric Acid. 

Chlorine and mucilage of 
Starch. 

Niti'ate or Chloride of 
Barium. 

Nitrate of Silver, Carbo- 
nate of Ammonia, and 
Nitric Acid. 

Phosphate of Sodium. 

Phosphate of Sodium. 

Ammonic Hydrate. 

Amnionic Hydrate. 
Chloride or Nitrate of 

Barium. 
Phosphate of Sodium. 

Solution in water. 

Acetate of Lead. 
Chloride or Nitrate of 

Barium. 
Phosphate of Sodium. 
Solution in Acids. 

Boiling Caustic Potash. 

Nitric Acid. 

Nitric Acid. 

Iodine. 

Microscope after exhaus- 
tion with Spt. and water. 

Incineration with Mercu- 
ric Oxide. 

Ammonia and Sulphate of 
Magnesium. 

Litmus-paper. 

Acetate of Lead. 

Hydrochloric Acid. 

Soda and Hydrochloric 
Acid. 

Sulphuric Acid and dilu- 
tion. 

Incineration. 

Boiling in Caustic Potash, 
Chloride of Ammonium. 

Caustic Potash and Sul- 
phide of Ammonium. 

Hydrochloric Acid. 

Sulphuretted Hydrogen. 



696 



APPENDIX. 

Table of Tests — Continued, 



Name of Preparation. ! 



Impurities. 



Cetaceum, 
Chinoidinuir, 



Cliloralf 



• \ 



Chloroformum Pu- 
rificatum, 



Chloroformum Ye- 
nale, 

Chrysarobinum, 



Cinchonidinse Sul- 
phas, 



Cinchonina, 



Coccus, 
Code in a, 



Copaiba, 

Creasotum, 

Greta Prseparata, 
Cupri Acctas, 



u 



Soft Fats. 

Alkaloidal Salts. 

Mineral matter. 

Acids. 
! Hydrochloric Acid. 

Mineral matter. 

Other organic impur- 
ity. 

Alcoholate (of Chlo- 
ral). 

Alcoholate (of Chlo- 
ral). 

Alcoholate (of Chlo- 
ral). 

Acids. 

Chlorides. 

Free Chlorine. 

Aldehyd. 

Hydrocarbons, etc. 



Chlorides. 
j Much Hydrocarbons, 
j ■ etc. 
[_ Xon-volatile matter. 

Mineral matter. 
f More than traces of 
I Quinine or Quini- 
i dine. 
! Organic impurity. 
| Sulphate of Cincho- 

nine. 
I Quinine or Quinidine 

(much). 
Organic impurity, 
[insoluble matter. 
Morphine. 
Fixed Oils. 

Turpentine. 
IGurjun Balsam. 
: Carbolic Acid. 

Carbolic Acid. 

Carbolic Acid. 

Carbolic Acid. 
I 

Barium or Strontium. 

Magnesium. 

Iron. 



Alkalies or alkaline 
I earths. 



Melting-point. 

Alkali to hot solution. 

Incineration. 

Litmus. 

Xitrate of Silver. 

Incineration. 

Sulphuric Acid. 

Chloroform. 



Boiling-point (above 97°). 

Formation of Iodoform. 

Litmus. 

Xitrate of Silver. 
Iodide of Potassium. 
Solution of Potash. 
Sulphuric Acid; odor on 

evaporation. 
Xitrate of Silver. 
Sulphuric Acid. 

Evaporation. 
Incineration. 

Fluorescence of solution. 

Sulphuric Acid. 
Quantitative Analysis. 

Fluorescence. 

Sulphuric Acid. 

Solution in cold water. 

Xitric Acid. 

Evaporation of volatile 
oil. 

Odor when heated. 

Oxidation. 

Albumen. 

Ferric Chloride. 

Glycerin. 

Dextro-rotation of polar- 
ized ray. 

Sulphate of Calcium. 

Phosphate of Sodium. 

Ferrocyanide of Potas- 
sium. 

Sulphuretted Hydrogen in 
alkaline solution. 

Evaporation after remov- 
ing Copper. 



APPENDIX. 

Table of Tests— Continued. 



697 



Name of Preparation, 



Cupri Sulphas, \ 

Elaterinum, \ 

Fel Bo vis Purifi- f 
catum, \ 

Ferri Garbonas J 
Saccharatus, 1 



Ferri Chloridum, - 



Ferri Citras, j 

Ferri ct Ammonii J 
Citras, I 

Ferri et Ammonii J 
Sulphas, | 

Ferri et Ammonii J 
Tartras, - j 

Ferri et Quininse J 
Citras, 

Ferri et Strychni- I 
nas Citras, J 

Ferri Hypophos- j 
p7a«, ( 

Ferri I o did am) 

Saccharatum, j 

Ferri Lactas, \ 

Ferri Sulphas, \ 

Ferrum Beductum, 



Glyccrlnum, 



Impurities. 



Foreign metals. 

Alkaloids. 

Mucus, crude Bile. 

Sulphate. 

General. 

Zinc or Copper. 

Alkalies. 

Nitric Acid. 

Ferrous Salt. 

Oxychloride. 

Fixed Alkalies. 

Fixed Alkalies. 

Aluminium. 

Fixed Alkalies. 

Fixed Alkalies. 

Ammonium Citrate. 
Fixed Alkalies. 

Ferric Phosphate. 

Calcium. 

Salts of Alkalies. 

Free Iodine. 
Sulphate, Citrate, Tar- 
trate, etc. 
Copper, Ferric Salt. 

Less than 80 per cent, 
Cane-sugar. 
Sugars and Dextrin. 
Sugars. 
Metallic Salts. 
Acrylic Acid. 
Hydrochloric Acid. 
Sulphuric Acid. 

Oxalic Acid. 
Iron Salty. 



Evaporation after remov- 
ing Copper. 

Tannic Acid; Salts of 
Platinum or Mercury. 

Incomplete solubility in 
spirit. 

Chloride or Nitrate of 
Barium. 

Quantitative Analysis. 

Ammonia, then Sulphu- 
retted Hydrogen. 

Evaporation and Inciner- 
ation after adding Am- 
monia. 

Sulphate of Iron and Sul- 
phuric Acid. 

Ferrocyanide of Potas- 
sium. 

Boiling with water (insol- 
uble). 

Litmus to residue on in- 
cineration. 

Litmus to residue on in- 
cineration. 

Potassic Hydrate, then 
Chloride of Ammonium. 

Litmus to residue on in- 
cineration. 

Litmus to residue on in- 
cineration. 

Heating with Potash. 

Litmus to residue on in- 
cineration. 

Solubility in Acetic Acid. 

Oxalate of Ammonium. 

Incineration and digestion 
with water. 

Mucilage of Starch. 

Acetate of Lead. 

Sulphuretted Hydrogen f 
solution. { 

Quantitative Analysis. 

Sulphuric Acid. 

Ignition on sand-bath. 

Potassio-oupric Tartrate. 

Ignition. 

Nitrate of Silver. 

Nitrate of Silver. 

Chloride or Nitrate of 
Barium. 

Chloride of Calcium. 

Sulphide of Ammonium. 



698 



APPENDIX. 



Table of Tests — Continued. 



Name of Preparation. 



Glycerinum, 
Gossypiam, 
Hydrargyri Chlor. 
Gorros., 

Hydrargyri Chlor. 
Mite, 

Hydrargyri Cya- 
niduni, 

Hydrargyri Iodi- 
dum Rubrum, 

Hydrargyri Iodi- 
dum Viride, 

Hydrargyri Oxi- 
dum Rubrum, 

Hydrargyri Sub- 
sulphas Flavus, 



Hydrargyri Sul- 
phidum Rubrum, 



Hydrargyrum, 

Hydrargyrum Am- 
moniatum, 

Hyoscyaminse Sid- 

phas, 
Ichthyocolla, 

Iodoformum, 

Iodum, 

Limonis Succus, 
Lin urn, 



Liq. Ammonii Ace- 
tatis, 



Impurities. 



Calcium Salts. 
Acids or Alkalies. 

Arsenic. 

Mercuric Chloride. 
Fixed soluble impuri- 
ties. 
Ammoniated Mercury, 

Mercuric Chloride. 

Chloride or soluble 

Iodide. 
Mercuric Iodide. 

Mercuric Nitrate. 
Mercurous Salt. 

Arsenic, Antimony. 

Chromates, Iodides, 
foreign Sul- 



Oxide of Mercury or 
Lead. 



Foreign metals. 
Mercurous Salt. 



Carbonate. 
Lead. 



Mineral matter. 

Gelatin. 

Alkali. 

Iodide. 

Mineral matter. 

Moisture. 

Chloride of Iodine. 

Cyanide of Iodine. 

Chlorine or Bromine. 
Deficiency of Citric 

Acid. 
Foreign Acids. 
Deficiency of Oil. 

Metals. 

Empyreumatic sub- 
stances. 



Oxalate of Ammonium. 
Litmus. 

Nascent Hydrogen. 

Sulphuretted Hydrogen. 
Residue on evaporating 

aqueous solution. 
Potash. 

Iodide of Potassium. 

Nitrate of Silver. 

Solution in Alcohol and 
evaporation. 

Strong heat. 

Solubility in Hydrochloric 

Acid. 
Digestion with Potash and 

addition of HC1. 
Acetate of Lead to Potash 

solution. 

Digest with diluted HN0 3 ; 

pass Sulphuretted Hy 

drogen. 
Hyposulphite of Sodium. 
Solubility in Hydrochloric 

Acid. 
Hydrochloric Acid. 
Sulphuric Acid to acetic 

solution. 

Incineration. 

Solubility in water. 

Litmus. 

Nitrate of Silver. 

Incineration. 

Solubility in Chloroform. 

Solubility in water. 

Formation of Prussian 
Blue. 

Nitrate of Silver. 

Sp. gravity and Quantita- 
tive Analysis. 

General Analysis. 

Extraction with Bisul- 
phide of Carbon. 

Sulphuretted Hydrogen or 
Sulphide of Ammonium. 

Odor when warmed, or 
Permanganate of Pot- 
ash. 



APPENDIX. 
Table of Tests — Continued. 



699 



Name of Preparation 


Impurities. 


Tests. 




Liq. Ammonii Ace- f 
tatis, \ 

Liquor Calcis. 


Fixed saline matter. 


Incineration. 




Alkalies and alkaline 
Carbonates. 


Precipitation by CO2; test- 
papers. 






Zinc or Copper. 


Excess of Ammonia and 
Sulphuretted Hydrogen. 




Liq. Ferri Aeeta- 


Fixed Alkalies. 


Excess of Ammonia, and 




tis, 




incineration. 






Ferrous Salt. 


Ferricyanide of Potas- 
sium. 






Zinc or Copper. 


Excess of Ammonia and 
Sulphuretted Hydrogen. 






Fixed Alkalies. 


Excess of Ammonia, and 




Liq. Ferri Chlo- 
ridi, 


Nitric Acid. 


incineration. 
Sulphuric Acid and Fer- 






rous Sulphate. 






Ferrous Salt. 


Ferricyanide of Potas- 
sium. 






Oxychloride. 


Solubility in water. 




Liq. Ferri Citratis, 


Ammonium Citrate. 


Potash. 




r 


Nitric Acid. 


Sulphuric Acid and Fer- 




Liq. Ferri Subsid- j 




rous Sulphate. 




'phatis, 


Ferrous Salts. 


Ferricyanide of Potas- 
sium. 




{ 


Nitric Acid. 


Sulphuric Acid and Fer- 




Liq. Ferri Tersul- J 




rous Sulphate. 




phatis, 


Ferrous Salts. 


Ferricyanide of Potas- 




{ 




sium. 




Liq. Hydrargyri f 
Nitratis, \ 


Mercurous Salt. 


Hydrochloric Acid. 




Liq. Pepsini, \ 


Mucus. 


Ammoniacal odor on keep- 
ing. 




( 


Carbonate (of Potas- 


Hydrochloric or Acetic 




1 


sium). 


Acid. 




1 


Alkaline earths. 


Carbonate of Sodium to 




Liquor Potassee, 




neutral solution. 






Sulphate. 


Chloride or Nitrate of 
Barium. 






Chloride. 


Nitrate of Silver. 




Liq. Potassii Ci- 
tratis, 


( Vide Potassii Citras.) 








Carbonate. 


Hydrochloric or Acetic 
Acid. 






Alkaline earths. 


Carbonate of Sodium to 




Liquor Sodse, 




neutral solution. 






Sulphate. 


Chlorido or Nitrate of 
Barium. 






Chloride. 


Nitrate of Silver. 




Liq. Sodii Silica- f 

tis, 
Liq. Zinci Chlo- ( 

ridi, j 


Much Alkali. 


Quantitative Analysis. 




( Vide Zinci Chlori- 






dum.) 






Lithil JJoizoks, 


. Salts of Alkalies. 


Alcohol and Ether. 





700 



APPENDIX. 

Table of Tests — Continued. 



Name of Preparation. 



r 
i 

Lithii Benzoas, \ 



::( 



Lithii Bromidum, ■{ 

I 

Lithii Carbonas, 

Lithii Citra, 
Lithii Salicylas 
Lupulinum, 

Lycopodium, 



Magnesia, 
Magnesia Ponde- \ 
rosa, 



Magnesii Carbo- 



Magnesii Citras I 
Gran., ] 



Magnesii Sulphas, - 

Magnesii Sulphis, 
Mangani Sulphas, 
Manna, j 

Mel, 



Impurities. 



Salts of alkaline 

earths. 
Metallic Salts. 
Cinnamic Acid, etc. 

Salts of Alkalies. 
Salts of alkaline 

earths. 
Metallic Salts. 

( Vide Lithii Benzoas.) 

Sand, etc. 
Pollen, Starch. 

Sand, or more than 5 

per cent, of ash. 
Carbonate. 
Chloride. 
Sulphate. 
Calcium. 

Aluminium or Cal- 
cium. 
Metals. 

Sulphate. 
Chloride. . 
Tartrate. 

Metallic Salts. 



Alkaline earths. 

Chloride. 

Alkaline Sulphates. 

Sulphate of Magne- 
sium. 
Iron. 
Copper. 
Alkalies or Magnesia. 

Insoluble matter. 

Deficiency of Mannite. 

Chlorides. 

Sulphates. 

Starch. 



Oxalate of Ammonium. 

Sulphuretted Hydrogen. 
( Vide Acidum Benzol 

cum.) 
Alcohol and Ether. 
Oxalate of Ammonium. 

Sulphuretted Hydrogen. 



Solubility in -water. 
Microscopical examina- 
tion. 
Incineration. 

Dilute Sulphuric Acid. 
Nitrate of Silver. 
Chloride of Barium. 
Oxalate of Ammonium to 

acetic solution. 
Carbonate and Chloride of 

Ammonium. 
Sulphydrate of Ammo- 
nium and Ammonia. 
Chloride of Barium. 
Nitrate of Silver. 
Acetate of Potassium and 

Acetic Acid. 
Sulphuretted Hydrogen or 

Sulphide of Ammo 

nium. 
Carbonate, Chloride, and 

Hydrate of Ammonium. 
Nitrate of Silver. 
Chloride of Barium, after 

removing Magnesia. 
Chloride of Barium. 

Tannic Acid. 

Sulphuretted Hydrogen, 

Ignition after removing 
Manganese. 

Digestion with Alcohol. 

Quantitative Analysis. 

Nitrate of Silver. 

Chloride of Barium. 

Iodine. 

Mixture with water and 
Alcohol. 

Amount of ash on incin- 
eration. 



Name of Preparation 



Morphina, 



Oleum uEthereum, 

Oleum Amygdalae j 
Amarae, 

Oleum Amygdalae f 
Expressum, \ 

Oleum Gaultheriae, \ 

Oleum Lavandulae f 
Florum, { 

Oleum Olivse, 

Oleum Sinapis ( 
Volatile, \ 

Oleum Theobromse, \ 



Olea Destillata, \ 
Opium, \ 

Pepsinum Saccha- ] 
ratum, -. j 

Petrolatum, J, 



Phosphorus, ■{ 

Physostigminae Sa- f 

licylas, \ 

Picrotoxinum, < 

Pilocarpine Hy- f 

droehlora8, \ 

Piper ilia, 



Plumbi Acetas, 
Plumb iCarh 



APPENDIX. 

Table of Tests — Continued, 

Impurities. 1 



701 



• i 



Other Alkaloids. 

Brucine, Strychnine, 

etc. 
Mineral matter. 
Acid (Sulpho-vinic). 
Alcohol or Chloroform. 
Nitrobenzol. 



Foreign oils. 

Chloroform or Alcohol- 
Oil of 



Alcohol. 
Foreign oils. 
Disulphide of Carbon. 
Paraffin, Wax, f 

Stearin, Tallow, etc. 1 

General. 

Deficiency in Mor- 
phine. 

Mucus. 

Fat or Resin. 

Oils, Fats, or Resin. 

Other organic impur- 

'ties. 
Arsenic. 

Sulphur. 

Mineral matter. 

Mineral matter. 
Alkaloids. 



Mineral matter. 

Mineral matter. 
Zinc, Alkalies, or alka- 
line earths. 
Copper. 
Zinc. 



Solubility in Sodic Hy 
drate. 

Sulphuric Acid, afterward 
Bichromate. 

Incineration. 

Litmus. 

Distillation at 80° C. 

Nascent Hydrogen, and 
then Chlorate of Potas- 
sium. 

Sulphuric Acid. 

Distillation at 80° C. 
Nitric Acid. 

Distillation at 80° C. 

General. 

Distillation at 50° C. 

Congelation-point after 

melting. 
Melting-point not above 

15° C. 
Solubility in Alcohol, 

gravity, etc. 
Quantitative Analysis. 

Turbidity of Hydrochloric 

Acid solution. 
Odor on ignition. 
Sulphuric Acid to its 

soap." 
Sulphuric Acid. 

Hydrosulphuric Acid to 
"is Phosphoric Acid. 

Chloride of Barium to its 
Phosphoric Acid. 

Incineration. 

Incineration. 
Precipitated by Tannic 

Acid, Platinum Salts, 

etc. 
Incineration. 

Incineration. 

Precipitation by S11 L >. and 
vaporation of filtrate. 

Excess of Ammonia. 

Sulphy drate of Ammo- 
nium after removing 
Lead. 



59 * 



702 



APPENDIX. 

Table of Tests — Continued. 



Name of Preparation 



Plumbi Carbonas, - 



Plumbi Iodidum, 



Plumbi Nitras, 



nbi Oxidu.m, < 



Impurities, 



Calcium (chalk). 

Sulphate of Barium or 
Lead. 

! Silicates. 

Alkaline Salts. 

Chromate (of Lead). 

Zinc, etc. 

Zinc, etc. 

Copper. 
Carbonate. 
Zinc, etc. 

Organic matter. 



Potassa, 



J (Chloride. 
1 (Sulphate. 
I Carbonate. 



[ Silica. 

Potassa cum CalceA 

Potassa Sulphurata, j Deficiency of Sulphide, 
f | Chloride. 
Sulphate. 
Silica. 



Potassii Acetas, 



Potassii Bicarbo- 
n as, 

Potassii Bichromas, 



Potassii Bitartras, 



Potassii Brora 
dum, 



Metals. 

Alkaline earths. 
Carbonate. 

Organic impurities. 

Sulphate. 
; Chloride. 
! Carbonate. 

'Sulphate. 
Sulphate. 
Chloride. 
Metals. 

More than 6 per cent. 1 
of Tartrate of Cal- 
cium. J 

Bromate. 

Iodide, 



Oxalate of Ammonium 
after removing Lead. 

Insolubility in Acetic f 
Acid. " j 

Insolubility in Acetic- 
Acid. 

Evaporation after remov- 
ing Lead. 

Solubility in Chloride of 
Ammonium. 

Evaporation after remov 
ing Lead. 

Evaporation after remov- 
ing Lead. 

Excess of Ammonia. 

Dilute Acids. 

Evaporation after remov- 
ing Lead. 

Color of solution, and Per 
manganate of Potash. 

Nitrate of Silver. 

Chloride of Barium. 

Effervescence with acids. 

Solubility in Alcohol. 

Solubility in Hydrochloric 
Acid. 

Sulphuretted Hydrogen. 

Nitrate of Silver. 

Chloride of Barium. 

Evap'n of acid solution, 
insolubility of residue. 

Sulphuretted Hydrogen or 
Sulphide of Ammonium. 

Carbonate of Sodium. 

Effervescence vvith Acetic 
Acid. 

Sulphuric Acid. 

Chloride of Barium. 
Nitrate of Silver. 
Chloride of Barium in the 

cold. 
Chloride of Barium. 
Chloride of Barium. 
Nitrate of Silver. 
Sulphuretted Hydrogen or 

Sulphide of Ammonium. 

Quantitative Analysis. 

I . 

j Sulphuric Acid. 

! Chlorine and mucilage of 

I Starch. 



APPENDIX. 
Table of Tests — Continued. 



703 



Name of Preparation 


Impurities. 


Tests. 




Potassii Bromi- J 
dum, 1 


Sulphate. 

More than 3 per cent. 


Chloride of Barium. 
Quantitative Analysis. 




of Chloride. 






f 


Silica, etc. 


Insolubility of residue on 
evaporation of acid 




i 
Potassii Garbonas, J. 


Alkaline earths. 


solution. 
Carbonate of Sodium. 




1 


Chloride. 


Nitrate of Silver. 




I 


Sulphate. 


Chloride of Barium. 




Potassii Chloras, - 


Sulphate. 


Chloride of Barium. 




Chloride. 


Nitrate of Silver. 




. 


Calcium. 


Oxalate of Ammonium. 






Carbonate. 


Effervescence with acids. 




Potassii Citras, 


Sulphate. 
Chloride. 


Chloride of Barium. 
Nitrate of Silver. 






Tartrate. 


Acetic Acid. 




Potassii Cyanidum, 


Carbonate. 


Effervescence with Acids. 




Potassii et Sodii J 
Tartras, "j 


Calcium. 
Sulphate. 


Oxalate of Ammonium. 
Chloride of Barium. 




Chloride. 


Nitrate of Silver. 




Potassii Ferrocy- 
anidum, 


Carbonate. 
Sulphate. 


Effervescence with Acids. 
Chloride of Barium. 




Chloride. 


Nitrate of Silver. 






Carbonate. 


Effervescence with Acids. 




Potassii- Hypo- 


Sulphate. 


Chloride of Barium. 




phosp>Ms } 


Phosphate. 


Magnesia mixture. 






Calcium. 


Oxalate of Ammonium. 






Iodate. 


Mucilage of Starch and 
Tartaric Acid. 




Potassii Iodidum, - 


Chloride or Bromide. 


Ammonia, Nitrate of Sil- 
ver, and Nitric Acid. 






Sulphate. 


Chloride of Barium. 






Metals. 


Sulphuretted Hydrogen or 
Sulphide of Ammonium. 




Potassii Nitras, 


Alkaline earths. < 


Carbonate of Ammo- J 
nium. 1 






Sulphate. 


Chloride of Barium. 






Chloride (of Sodium). 


Nitrate of Silver. 






Nitrate. 


Sulphuric Acid and Fer- 
rous Sulphate to decol- 
orized solution. 




Potassii Perman- 


Chloride. 


Nitrate of Silver to decol- 




yanas, 




orized solution. 




I 


Sulphate. 


Nitrate of Barium after 
removing Manganese 
by Ammonia. 






Alkaline earths. 


Carbonate or Phosphate 
of Ammonium. 




Potassii Sxdplias, - 


Metals. 


Sulphuretted Hydrogen or 
Sulphide oi' Ammonium. 






Chloride. 


Nitrate of Silver. 




Potassii Sut ph is, 


Sulphate. 


Chloride of Barium. 





704 



APPENDIX. 

Table of Tests — Continued. 



Name of Preparation, 



Potassii Tartras, 



Quinidinse Sul- 
phas, 



Quininse Bisul- 
phas, 



Quininse Hi/dro- 
bromas, 



Quininse Hydro- 
chloras, 



; Sulphas, 



Quininse Valeri- 

anas, 
Rheum, 



Saccha 



Saccharum Lac- 



Salicinum, 
Santoninum, 



Sapo, 



Sapo Viridis, 



Impurities. 



Calcium. 

Sulphate. 

Chloride. 

Organic impurities. 

Morphine. 

Cinchonine, Quinine, 
or Cinchonidine. 

Organic impurities. 

Cinchonine, Cincho- 
nidine, or Quini- 
dine. 

Organic impurities. 

Free water. 

Sulphates of Quini- "] 
dine, Cinchoni- 
dine, or Cincho- 
nine. j 

Organic impurities. 

Free water. 

Sulphate. 

Barium. 

Cinchonine, etc. 

Organic impurities. 

Barium. 

Sulphate. 

Organic impurities. 

Ammonia (Sulphate) 

Free water. 

Cinchonine Sulphate, 
etc. 

Organic impurities. 

Sulphate. 

Turmeric. 

Insoluble salts, etc. 

Grape-Sugar or In- 
verted Sugar. 

Cane-Sugar. 

Mineral matter. 
Mineral matter. 
More than 34 per cent, 

of water. 
Animal Fats. 

Carbonate of Sodium. 
Silica and insoluble 

matter. 
Metals. 
More than 4 per cent. 

of water. 
Free Fats. 



Oxalate of Ammonium. 

Chloride of Barium. 

Nitrate of Silver. 

Sulphuric Acid. 

Nitric Acid. 

Iodide of Potassium and 

Ammonic Hydrate. 
Sulphuric Acid. 

Sulphate of Ammonium 
and Ammonia. 

Sulphuric Acid. 

Drying upon water-bath. 

Ammonia, as for Quinine. 

Sulphuric Acid. 
Drying upon water-bath. 
Chloride of Barium. 
Sulphuric Acid. 
Ammonia, as for Quinine. 
Sulphuric Acid. 
Sulphuric Acid. 
Chloride of Barium. 
Sulphuric Acid. 
Boiling with milk of lime. 
Drying on water-bath. 
Ammonium Hydrate. 

Sulphuric Acid. 

Chloride of Barium. 

Boracic Acid. 

Aqueous or alcoholic solu- 
tion on standing. 

Nitrate of Silver and Am- 
monic Hydrate. 

Sulphuric Acid. 

Incineration. 
Incineration. 
Drying at 110° C. 

Gelatinization of 4 per 
cent, alcoholic solution. 
Solubility in alcohol. 
Solubility in water. 

Sulphuretted Hydrogen. 
Drying at 100° C. 

Digestion of dried soap in 
Benzol. 



APPENDIX. 

Table of Tests— Con tinned. 



705 



Name of Preparation 



Sapo Viridis, -j 

I 

Scammonium, \ 

Scammonii Resina, < 
Soda, 



Sodii Acetas, 



Sodii Arsenias, 
Sodii Benzoas, 

Sodii Bicarbonas, - 

Sodii Bisitlphis, 
Sodii Boras, ■{ 

I 

Sodii Bromidum, \ 
Sodii Carbonaa, 



Impurities. 



Insoluble Carbonates. 



Chalk. 
Starch, 
llesin of Guaiacum. 

Resin of Jalap. 
Organic matter. 

Chloride. 

Sulphate. 

Carbonate. 

Silica or Carbonate. 

Chloride. 

Sulphate. 

Silica. 



Metals. . 

Alkaline earths. 
Carbonate. 

Organic impurities. 

Arsenite. 

Excess or deficiency ~) 
of water of crys- > 
tallization. J 

( Vide Acidum Benzoi- 
cum.) 

Chloride. 

Sulphate. 

Ammonium Salts. 

Carbonate. 



Sulphate. 

Carbonate. 

Chloride. 

Sulphate. 

Alkaline earths. 

Metals. 

Bromato. 

Iodide. 

Sulphate. 

More than 3 per cent. 

of Chloride. 
Chloride. 



Dilute Acids to residue 
from alcohol and water. 

Iodine to residue from 
alcohol and water. 

Effervescence with Acids. 

Iodine. 

Inner surface of potato- 
paring. 

Insolubility in Ether. 

Color of aqueous solution ; 
Sulphuric Acid. 

Nitrate of Silver. 

Chloride of Barium. 

Effervescence with Acids. 

Solubility in Alcohol. 

Nitrate of Silver. 

Chloride of Barium. 

Insolubility of residue on 
evaporating acid solu- 
tion. 

Sulphuretted Hydrogen or 
Sulphide of Ammonium, 

Carbonate of Sodium. 

Effervescence with Acids. 

Sulphuric Acid. j 

Sulphuretted Hydrogen 
water. 

Quantitative Analysis. 



Nitrate of Silver. 

Chloride of Barium. 

Boiling with solution of 
Soda. 

Chloride of Barium in 
the cold, and Quanti- 
tative Analysis. 

Chloride of Barium. 

Effervescence with Acids. 

Nitrate of Silver. 

Chloride of Barium. 

Carbonate of Sodium. 

Hydrosulphurio Acid. 

Sulphuric Acid. 

Chlorine-water and muoi- 
ige of Starch. 

Chloride o( Barium. 

Quantitative Analysis. 



Nitrate of Silv 



706 



APPENDIX. 
Table of Tests— Continued. 



Name of Preparation. 



Sodii Carbonas. 



Sodii Chloras, 



Sodii Chloridum. 



Sodii Hyjiophos- 
p>his, 



Sodii Hyposul- 
pli is, 



Sodii Iodidum, 



Sodii Nitras, 



Sodii Phosphas, 



Sodii Pyrophos- 



Sodii Salicylas, 



Sodii Santoninas, 



Impurities. 



Sulphate. 

Metals. 

Alumina. 

Potassium. 

Calcium. 

Chloride. 

Sulphate. 

Metals. 

Alkaline earths. 

Sulphate. 

Iodide or Bromide. 



Calcium. 

Potassium. 

Carbonate. 

Sulphate. 

Phosphate. 

Sulphate. 

Carbonate. 

Iodate. 

Sulphate. 

Chloride or Bromide. 



Alkaline earths. 

Potassium. 

Sulphate. 

Chloride. 

Iodide. 

Carbonate. 
Sulphate. 
Chloride. 
Metals. 

Carbonate. 
Sulphate. 
Chloride. 
Metals. 

Carbonate. 

Sulphate. 

Chloride. 

Organic impurities. 

Alkaline earths. 

Alkaloids. 



Chloride of Barium. 

Hydrosulphuric Acid. 

Ammonia and Chloride of 
Ammonium. 

Bitartrate of Sodium. 

Oxalate of Ammonium. 

Nitrate of Silver. 

Chloride of Barium. 

Hydrosulphuric Acid or 
Sulphide of Ammonium. 

Carbonate of Sodium. 

Chloride of Barium. 

Chlorine-water and Starch 
to residue on evaporat- 
ing alcoholic solution. 

Oxalate of Ammonium. 

Bitartrate of Sodium. 

Effervescence with Acids. 

Chloride of Barium. 

Ammonia and Sulphate of 
Magnesium. 

Chloride of Barium. 

Effervescence with Acids. 

Mucilage of Starch and 
Tartaric Acid. 

Chloride of Barium. 

Ammonia, Nitrate of Sil- 
ver, and Nitric Acid, 

Sulphuretted Hydrogen or 
Sulphide of Ammonium. 

Carbonate of Ammonium. 

Bitartrate of Sodium. 

Chloride of Barium. 

Nitrate of Silver. 

Chlorine-water and Muci- 
lage of Starch. 

Effervescence with Acids. 

Chloride of Barium. 

Nitrate of Silver. 

Sulphuretted Hydrogen or 
Sulphide of Ammonium. 

Effervescence with Acids. 

Chloride of Barium. 

Nitrate of Silver. 

Sulphuretted Hydrogen or 
Sulphide of Ammonium, 

Effervescence with Acids. 

Chloride of Barium. 

Nitrate of Silver. 

Sulphuric Acid. 

Carbonate of Sodium. 

Precipitate with Tannic 
or Picric Acid. 



APPENDIX. 

Table of Tests — Continued. 



707 



Name of Preparation, 



Sodii Sulphas, 



Sodii Sulphis, 
Sodii Sulphocar- 
bolas, 



Spiritus JEtheris 
Nitrosi, 



Spiritus Ammonii 



Spiritus Frumenti, 



Spiritus Vini Gal- 



Strychnina, 
Sulphuris lodi- 
dum, 

Sulphur Lotum, 



Sulphur Preecipi- 
tatum, 



Impurities. 



Carbonate. 

Chloride. 

Metals. 

Ammonium Sulphate. 
Sulphate. 

Sulphate. 

Deficiency of Nitrite 

of Ethyl. 
Free Acid. 

General. 

Empyreumatic s 
stances. 



Carbonate. 
Sulphate. 
Chloride. 
Calcium. 

Metals. 

Fusel Oil. 

More than .25 per cent, 
of solids. 

Sugar, Glycerin, 01 
spices. 

Excess of Acid. 

Deficiency in alcohol. 

Fusel Oil. 

Amyl Alcohol. 

Methyl Alcohol, Al- 
dehyd, or Oak Tan- 
nin. 

Methyl Alcohol. 



Mineral matter. 

Free Acid. 
Arsenious Sulphide. 

Arsenious Acid. 
Free Acid. 

Sulphate of Calcium. 

Alkalies. 
Alkaline earths. 

Arsenious Sulphide. 
Arsenious Acid. 



Effervescence with Acids. 
Nitrate of Silver. 
Hydrosulphuric Acid oi 
Sulphide of Ammonium 
Boiling with Soda. 
Chloride of Barium. 

Chloride of Barium. 

Quantitative Analysis. 

Effervescence with Bicar- 
bonate of Sodium. 

Specific gravity. 

Neutralization with Sul- 
phuric Acid and odor, 
and Permanganate of 
Potassium. 

Effervescence with Acids. 

Chloride of Barium. 

Nitrate of Silver. 

Oxalate of Ammonium. 

Sulphuretted Hydrogen or 
Sulphide of Ammonium. 

Odor on evaporation. 

Drying at 100° C. 

Characters of solids 

evaporation. 
Quantitative Analysis. 
Specific gravity. 
Odor on evaporation. 
Sulphuric Acid. 
Solution of Potassa. 



Permanganate of Potas 

sium. 
Nitric Acid. 

Incineration. 

Litmus. 

ash with Ammonia; 

evaporate fo dryness. 
Hydrosulphuric Acid. 
Litmus. 

Chloride of Barium. 
Carbonate of Ammonium 

and Ammonia. 
Solubility in water. 
Solution in Hydrochloric 

Acid, and evaporation. 
Ammonia Hydrate. 
Hydrosulphuric Acid. 



708 



APPENDIX. 

Table of Tests — Continued. 



Name of Preparation. 



Sulphur Sublima- 
tum, 

Syrupus Acidi Hy- 
driodici, 

Synqms Ferri 

Bromidi, 
Syrupus Ferri Io- 

didi, 
Tamarindus, 

Thymol, 



Tinctara Ferri 
Acet.j 



Tinctura Ferr\ 
Chloridi, 



Veratrina, 



Vinum Album, \ 



Vinum Album i 
Fortius, i 



Vinum Ruhrum, 



Zinci Acetas, 
Zinci Bromidum, 



Impurities. 



Earthy matter. 

Free Iodine. 
Sulphuric Acid. 
Hydrochloric Acid. 

Free Bromine. 



Traces of Copper. 
Carbolic Acid. 

Zinc and Copper. 

Fixed Alkalies. 

Ferrous Salt. 

Zinc or Copper. 

Fixed Alkalies. 

Nitric Acid. 

Ferrous Salt. 

Oxychloride. 

Mineral matter. 

Tannic Acid. 

Excess or deficiency of 

Alcohol. 
Excess or deficiency of 

Acid. 
Excess or deficiency of 

Alcohol. 
Excess or deficiency of 

Alcohol. 
Excess or deficiency of 

Acid. 
Aniline colors. 



Lead or Copper. 
Iron, Aluminium, or 

alkaline earths. . 
Salts of Alkalies or 

alkaline earths. 

Lead or Copper. 
Iron, Aluminium, or 
alkaline earths. 



Incineration. 

Mucilage of Starch. 
Chloride of Barium. 
Nitrate of Silver and Am- 



Mucilage of Starch. 

Mucilage of Starch. 

Iron. 

Ferric Chloride to satura- 
ted aqueous solution. 

Hydrosulphuric Acid, af- 
ter removing Iron. 

Evaporation and ignition, 
after removing Iron. 

Ferricyanide of Potas- 
sium. 

Hydrosulphuric Acid, af- 
ter removing Iron. 

Evaporation and ignition, 
after removing Iron. 

Sulphuric Acid and Fer- 
rous Sulphate. 

Ferricyanide of Potas- 
sium. 

Dilution with water, and 
boiling. 

Incineration. 

Ferric Chloride. 

Quantitative Analysis. 

Quantitative Analysis. 
Quantitative Analysis. 
Quantitative Analysis. 
Quantitative Analysis. 

Ammonia, Ether; evap- 
oration of ethereal solu- 
tion in contact with silk. 

Hydrosulphuric Acid. 

Carbonate of Ammonium 
in excess. 

Removal of Zinc; evap- 
oration and ignitiou of 
filtrate. 

Hydrosulphuric Acid. 

Carbonate of Ammonium 
in excess. 



APPENDIX. 
Table or Tests— Continued. 



709 



Name of Preparation. 



Zinci Bromidum, ■ 



Zinci Carbonas 
Prsecipitatus, 



Zinci Chloridtim, 



Zinci Iodidum, J 
Zinci Oxidum, [ 

Zinci Phosphidum, 

Zinci Sulphas, < 



Zinci Valerianae) 



ianas, < 



Zincum, 



Impurities. 



Alkalies or alkaline 

earths. 
Lead or Copper. 
Iron, Aluminium, or 

alkaline earths. 
Salts of Alkalies or 

alkaline earths. 
Basic Chloride. 

Lead or Copper. 
Iron, etc. 

Alkalies or alkaline 

earths. 
Same as other Zinc 

Salts. 
Lead or Copper. 
Chloride. 
Same as other Zinc 

Salts. 
Alkalies or alkaline 

earths. 
Butyrate of Zinc. 
Arsenic. 

Lead, Iron, or Copper. 



Evaporation and ignition, 
after removing Zinc. 

Hydrosulphuric Acid. 

Carbonate of Ammonium 
in excess. 

Evaporation and ignition, 
alter removing Zinc. 

Alcohol to aqueous solu- 
tion. 

Hydrosulphuric Acid. 

Carbonate of Ammonium 
in excess. 

Evaporation and ignition, 
after removing Zinc. 



Hydrosulphuric Acid. 
Nitrate of Silver. 



Evaporation and ignition, 
after removing Zinc. 

Acetate of Copper. 

Nascent Hydrogen and 
Nitrate of Silver. 

Excess of Ammonia. 



710 



APPENDIX. 



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APPENDIX. 



711 



The Proportion by Weight of Absolute or Real Alcohol (C 2 H 5 HO) in 
100 Parts of Spirits of Different Specific Gravities (Fownes). 





Per- 




Per- 




Per- 


Sp. gr. at 60° 


centage 


Sp. gr. at 60° 


centage 


Sp. gr. at 60° 


centage 


(15°. 5 0.). 


of real 


(15°.5 C). 


of real 


(15°.5 C). 


of real 




alcohol. 




alcohol. 




alcohol. 


0.9991 ... 


... 0.5 


0.9511 .. 


... 34 


0.8769 .. 


... 68 


0.9981 ... 


... 1 


0.9490 .. 


.. 35 


0.8745 .. 


... 69 


0.9965 ... 


... 2 


0.9470 ... 


.... 36 


0.8721 .. 


... 70 


0.9947 ... 


... 3 


0.9452 ... 


... 37 


0.8696 .. 


... 71 


0.9930 ... 


.. 4 


0.9434 ... 


... 38 


0.8672 .. 


... 72 


0.9914 ... 


... 5 


0.9416 .. 


... 39 


0.8649 .. 


... 73 


0.9898 ... 


.. 6 


0.9396 ... 


... 40 


0.8625 .. 


... 74 


0.9884 ... 


.. 7 


0.9376 ... 


... 41 


0.8603 ... 


... 75 


0.9869 ... 


.. 8 


0.9356 ... 


... 42 


0.8581 .. 


... 76 


0.9855 ... 


.. 9 


0.9335 ... 


... 43 


0.8557 ... 


... 77 


0.9841 ... 


.. 10 


0.9314 ... 


... 44 


0.8533 .. 


... 78 


0.9828 ... 


.. 11 


0.9292 ... 


... 45 


0.8508 ... 


... 79 


0.9815 ... 


.. 12 


0.9270 ... 


... 46 


0.8483 ... 


... 80 


0.9802 ... 


.. 13 


0.9249 ... 


... 47 


0.8459 ... 


... 81 


0.9789 ... 


.. 14 


0.9228 ... 


... 48 


0.8434 ... 


... 82 


0.9778 ... 


.. 15 


0.9206 ... 


... 49 


- 0.8408 ... 


... 83 


0.9766 ... 


.. 16 


0.9184 ... 


... 50 


0.8382 ... 


... 84 


0.9753 ... 


.. 17 


0.9160 ... 


... 51 


0.8357 ... 


... 85 


0.9741 ... 


.. 18 


0.9135 ... 


... 52 


0.8331 ... 


... 86 


0.9728 ... 


.. 19 


0.9113 ... 


... 53 


0.8305 ... 


... 87 


0.9716 ... 


.. 20 


0.9090 ... 


... 54 


0.8279 ... 


... 88 


0.9704 ... 


.. 21 


0.9069 ... 


... 55 


0.8254 ... 


... 89 


0.9691 ... 


.. 22 


0.9047 ... 


... 56 


0.8228 ... 


... 90 


0.9678 ... 


.. 23 


0.9025 ... 


... 57 


0.8199 ... 


... 91 


0.9665 ... 


.. 24 


0.9001 ... 


... 58 


0.8172 ... 


... 92 


0.9652 ... 


.. 25 


0.8979 ... 


... 59 


0.8145 ... 


... 93 


0.9638 ... 


.. 26 


0.8956 ... 


... 60 


0.8118 ... 


... 94 


0.9623 ... 


.. 27 


0.8932 ... 


... 61 


0.8089 ... 


... 95 


0.9609 ... 


.. 28 


0.8908 ... 


... 62 


0.8061 ... 


... 96 


0.9593 ... 


... 29 


0.8886 ,.. 


... 63 


0.8031 ... 


... 97 


0.9578 ... 


.. 30 


0.8863 ... 


... 64 


0.8001 ... 


... 98 


0.9560 ... 


.. 31 


0.8840 ... 


... 65 


0.7969 ... 


... 99 


0.9544 ... 


.. 32 


0.8816 ... 


... 66 


0.7938 ... 


... 100 


0.9528 ... 


.. 33 


0.8793 ... 


... 67 







(12 APPENDIX. 






THE ELEMENTS. 




Symbols and atomic 


Atomic 


value. 


■weight. 


Aluminium (Al 2 vr ) Al 1 


27 


Antimony (Sb m ) ( n9 - 6 - Schneider 


Cooke"\ 


Sb v 


120 


Arsenicum (As m ) 




As v 


74.9 


Barium 






Ba 11 


136.8 


Beryllium (Glucinum) 






Be 11 


9.3 


Bismuth (Bi 111 ) ( 2075 ' Dumas ) 






Bi v 


210 


Boron ( 10 - 9 - Berzelius ) 






B nr 


11 


Bromine ( 79 - 75 > stas ) 






Br 1 


79.8 


Cadmium ( m - 7 - Lenssen ) . 






Cd m 


111.8 


Csesium 






Cs 1 


132.7 


CalfMUTn f 39,9, Erdmann and Marehand\ 






Ca" 


40 


Carbon (C ir ) 






QIV 


12 


Cerium (Ce Iir ) . 






Ce VI 


138 


Chlorine ( 3bM8 > stas ) 






CI 1 


35.4 


Chromium (Cr 2 TI ) 






Cr vl 


52.4 


Cobalt (Co 11 ) 






Co TI 


58.6 


Copper 






Cu 11 


63.2 


Didymium? (^Mendelejeff) 






D TI 


142.4 


Erbium? ("LMendelejeff) _ 






Eb n 


168.9 


Fluorine ( 18 - 96 - Luca - Louget ) 






F 1 


19 


Gallium 






Ga rv 


69.8 


Germanium (^.Boisbandran, 72.75, Winkler^ 




Glucinum. See Beryllium. 




GoldCAu 1 ) ( 196 - 2,Berzelius ) . . . Au m 


196.85 


Hydrogen .... 




H 1 


1 


Indium . . . 




In VI 


113.4 


Iodine ( 126 - 533 ' stas ) 




I 1 


126.6 


Iridium .... 




Ir iv 


192.5 


Iron (Fe n & Fe 2 YI ) 




Fe vr 


55.9 


Lanthanum 




La rI 


139.3 


Lead ( n Pb n ) ( 206 - 4 ' stas ) 




Pb IV 


206.5 


Lithium .... 




L 1 


7 


Magnesium (™ M - Dumas ) 




Mg" 


24 


Manganese Mn TI & Mn IT ) 




Mn VI 


54.8 


MerCUl'V f 199 8 ' Erdmaun & Marchand\ 




Hg n 


199.7 


Molybdenum 




Mo VI 


95.9 


Nickel (Ni 11 ) 




Ni VI 


58.6 


Niobium .... 




Nb v 


93.7 


Nitrogen (N 1 & N m ) (»*■«». s^) 




N v 


14 


Osmium ..... 




Os IV 


195 


Oxygen ( 15 - 96 ' s,as ) 






O rl 


16 





APPENDIX. 


715 




Symbols and atomic 


Atomic 




value. 


weight. 


Palladium .... 


Pd IV 


106 


PhoSphorUS (P IU ) (30-96, Schrotter^ 


P V 


31 


Platinum ( 19788 > Audrews ) . 


Pt lV 


194.4 


Potassium ( 39 - w - stas ) 




K 1 


39 


Rhodium 




Rh lv 


104.1 


Rubidium 




Rb r 


85.3 


Ruthenium . 




Ru lv 


104.2 


Scandium. 








Selenium or Selenion 




Se VI 


78.8 


Silicon 




Si IV 


28.3 


Silver ( 107 - 66 > stas ) . 




. Ag 1 


107.7 


Sodium ( 2298 - stas ) . 




Na 1 


23 


Strontium 




Sr 11 


87.4 


Sulphur (S 11 & S IV ) 




S VI 


32 


Tantalum 




Ta v 


182 


Tellurium 




Te VI 


125 


Thallium 




T1 m 


203.5 


Thorinum or Thorium 




Th 11 


231.4 


Tin (Sn n ) . 




Sn IV 


117.7 


Titanium 




Ti iv 


48 


Tungsten 




W VI 


183.6 


Uranium 




U VI 


239.8 


Vanadium 




v v 


51 


Ytterbium^ . 




Yb 


173 


Yttrium 




Y n 


88.9 


Zinc 




Zn 11 


64.9 


Zirconium 




Zi lv 


90.4 



The quantivalence or atomic value of some elements is, apparently, 
variable ; in the above Table the full coefficients are given in the 
column of symbols, other common values in parentheses. 

Atomic weights are sometimes obscurely termed equivalents. 

Other elements than the above exist. They are very rare. Some 
of the rarer so-called elements may not be truly elementary. 

Students must expect the figures representing the atomic weights 
of elements to vary slightly from time to time, in accordance with 
the advancement of knowledge in the directions of purity of ma- 
terials and improvements in manipulation, and as regards modes of 
research and realization of chemical and physical analogies amongst 
elements. 



60 « 



INDEX 



Abies bahamea, 409, 422. 

canadensis, 409. 

exeelsa, 421. 
Abrin, 494. 

Abrus precatorim, 494. 
Absinthium, 414. 
Absinthol, 414. 
Absolute alcohol, 437. 
Abstracts, 574. 
Acacia catechu, 358. 

8iima, 358. 
Acacise gummi, 113. 

impurities in, 685. 
Acetal, 476. 
Acetanilide, 514. 

Acetate of ammonium, solution of, 
91. 

amyl, 403. 

copper, 190. 

ethyl, 298, 403. 

iron, 148. 

lead, 208. 

potassium, 68. 

sodium, 82. 

zinc, 133. 
Acetates, 296. 

analytical reactions of, 299. 

decomposition of aqueous solu- 
tion of, 279. 

volumetric estimation of, 623. 
Acetic acid, 298, 474. 

ether, 299, 403. 

glacial, 298, 583. 

volumetric estimation of free, 
623. 
Acetic series of acids, 474. 
reactions, 481. 

aldehyde, 475. 

anhydride, 463. 
Acetone," 299, 488. 
Acetonitrate of barium, 125. 

of iron, 155. 
Acetonitrilo, 474. 
Acetum, 297. 

cantharidis, 297. 

colvhici, 297. 

lobelia, 297. 

opii, 297. 



Acetum — 

sanguinarise, 297. 

scillse, 297. 
Acetyl, 297. 
Acetyl chloride, 394. 
Acetylene, 409. 

series of hydrocarbons, 408. 
Acetylenes, relation to paraffins and 

olefines, 408. 
Acid, acetic, 297, 475. 

glacial, 298, 583. 

aconitic, 324. 

acrylic, 480. 

amidacetic, 536. 

amido-succinamic, 486. 

amyric, 422. 

anemonic, 335. 

angelic, 412. 

arabic, 470. 

arachidic, 481. 

arsenic, 165. 

arsenious, 165. 

behenic, 481. 

benzoic, 335, 689. 

benzene-disulphonic, 448. 

benzene-sulphonic, 447. 

boric, 333, 689. 

bromic, 295. 

butyric, 363, 479. 

camphoric, 418. 

camphoronic, 418. 

cantharidic, 418. 

capric, 481. 

caproic, 454, 481. 

caprylic, 454, 481. 

carbamic, 480. 

carbazotic, 448. 

carbolic, 449, 582, 689. 
impure, 449. 

carbonic, 30, 311. 

oarminio, 337. 

cateohuic, 358. 

cathartic, 491. 

oathartogenio, 491. 

oerotic, 397, 179, 4S1. 

cetraric, 'A'-u. 

ohavicio, 527. 

ohelidonio, 522. 

715 



716 



Acid, chloric, 291, 293. 
chlorous, 351. 
cholalic, 536. 
chromic, 236, 689. 

anhydrous, 236. 
chrysammic, 430. 
chrysatropic, 520. 
chrysophanic, 337. 
cinnamic, 337, 485. 
citric, 323, 690. 
colopholic, 419. 
colophonic, 419. 
cop ai vie, 422. 
cornic, 338. 
cresotic, 483. 
cresylic, 447. 
crotonic, 480. 
cryptophanic, 558. 
cuminic, 414. 
cyanic, 338. 
dextroracemic, 319. 
dextrotartaric, 319. 
dihydroxyacetic, 481. 
dihydroxybenzoic, 483. 
dihydroxybutyrie, 481. 
dihydroxypropionic, 481. 
dihydroxysuccinic, 486. 
dithionic, 346. 
elaidic, 480. 
equisitic, 324. 
ergotinic, 421. 
erucic, 456. 
ethylidene lactic, 480. 
ethylformic, 479. 
ethylic, 481. 
ethyl-sulphuric, 441. 
eugenic, 413. 
ferulaic, 423. 
filicic, 455. 
fluoric, 342. 
formic, 338, 474, 481. 
gallic, 339, 359, 690. 
gallotannic, 484. 
gambogic, 423. 
gaultheric, 404. 
gelseminic, 396. 
gentianic, 494. 
gentisic, 494. 
glacial acetic, 298, 583. 
glutanic, 487. 
glyceric, 481. 
glycyrrhizic, 494. 
glyoxylic, 481. 
guaiaconic, 495. 
guaiaretic, 495. 
guaiaretinic, 495. 
gummic, 470. 
hemidesmic, 339. 
hep ty lie, 481. 



Acid, hexylie, 481. 

hippuric, 339, 565, 568. 
homotartaric, 487. 
hydriodic, 270. 
hydrobromic, 266, 622, 690. 
hydrochloric, 29, 263, 690. 

common, 263. 

dilute, 263. 
hydrocyanic, 276, 280, 690. 

dilute, 279. 
hydroferridcyanic, 341. 
hydroferrocyanic, 340. 
hydrofluoric, 342. 
hydrosulphuric, 300. 
hydroxyacetic, 407, 479. 
hydroxybenzoic, 482. 
hydroxybutyric, 481. 
hydroxycaproic, 481. 
hydroxydodecylic, 481. 
hydroxyformic, 479, 481. 
hydroxylieptylic, 481. 
hydroxyotylic, 481. 
hydroxypentylic, 481. 
hydroxy-propane-tricarboxylic, 

488. 
hydroxypropionic, 481. 
hydroxysuccinic, 486. 
hydroxytoluic, 483. 
hypochlorous, 292. 
hypophosphoric, 352, 
hypophosphorous, 343. 
hyposulphurous, 344. 
iodic, 295. 
isoheptoic, 417. 
isopropylacetic, 479. 
jalapic, 495. 
lactic, 347, 622, 690. 
laevoracemic, 319. 
laevotartaric, 319. 
larixinic, 359. 
lauric, 465. 
leucic, 481. 
lithic, 361. 
lupulinic, 423. 
malic, 348. 
nialonic, 487. 
mastichic, 421. 
meconic, 349, 506. 
mellitic, 488. 
mesoxalic, 487. 
metaboracic, 333. 
metagummic, 470. 
metantimonic, 179. 
metaphosphoric, 349. 
metastannic, 240. 
methacrylic, 480. 
methylic, 481. 
methylformic, 475. 
mimotannic, 358. 



INDEX. 



717 



Acid, mucic, 462. 
muriatic, 263. 
myristic, 481. 
myrrhic, 424. 
naphthalic, 335. 
nitric, 286, 288, 690. 

dilute, 286. 
nitre-hydrochloric, 185, 287. 

dilute, 287. 
nitromuriatic, 287. 
nitrous, 350. 
nonylic, 481. 
octylic, 481. 
cenanthylic, 481. 
oleic, 451, 690. 
ophelic, 351. 
opianic, 380. 
orthophosphoric, 351. 
oxalic, 315. 

chemically pure, 315. 
oxymalonic, 487. 
oxysuccinic, 487. 
palmitic, 462, 479, 481. 
paraffinic, 397. 
paratartaric, 319. 
parietinic, 338. 
pelargonic, 481. 
pentathionic, 346. 
penthylic, 481. 
perchloric, 293. 
phenic, 447. 
phenolsulphonic, 448. 
phosphoantimonic, 555. 
phosphomolybdic, 555. 
phosphoric, 25, 328, 351, 690 

dilute, 328. 

glacial, 329. 
■ phosphorous, 351. 
phosphotungstic, 555. 
phthalic, 335. 
picric, 448, 538. 
pimaric, 419. 
pinic, 419. 
piperic, 398. 
propionic, 499. 
propylformic, 479. 
propylic, 479. 

propane-tricarboxylic, 488. 
prussic, 277. 
pyrogallic, 360. 
pyroligneous, 296. 
pyromellitic, 48S. 
pyrophosphoric, 352. 
pyrotartaric, 487. 
quillaic, 498. 
racemic, 319. 
rheic, 337. 
rhubarbaric, 337. 
rutic, 154. 



Acid, saccharic, 462. 

salicylic, 404, 482, 691. 

salicylous, 404. 

santonic, 488. 

sarcolactic, 348. 

sclerotic, 420. 

sclerotinic, 420. 

silicic, 354. 

stannic, 240. 

stearic, 452, 479, 481. 

succinic, 355. 

sulphethylic, 441. 

sulphindigotic, 289. 

sulphindylic, 289. 

sulphocarbolic, 448. 

sulphocyanic, 356. 

sulphophenic, 448. 

sulphosalicylic, 484. 

sulphovinic, 441. 

sulphuric, 306, 690. 

sulphuric, aromatic, 309. 
dilute, 309. 

sulphurous, 302, 304, 690. 

sulphydric, 300. 

sylvic, 419. 

tannic, 357, 691. 

tartaric, 317, 318, 691. 

tetrathionic, 346. 

tiglic, 457. 

toxicodendric, 360. 

tricarballylic, 488. 

trihydroxybenzoic, 483, 484. 

trithionic, 346. 

tropic, 392. 

uric, 353. 

valerianic, 361, 416, 443, 479. 
Acid carbonate of potassium, 70, 313. 

carbonate of sodium, 82. 

salts, 73, 301. 

solution of arsenic, 165. 

tartrate of potassium, 61, 79. 

tartrate of sodium, 79. 
Acids, analytical detection of, 368. 

antidotes to, 266. 

definition of, 260. 

free, estimated, 657. 

of chlorine, 294. 

quantitative estimation of, 620. 

volumetric estimation of official, 
620. 
Acids of acetic sories, 474. 

acrylic, 480. 

benzoic or aromatic, 480. 

oinnamio, 484. 

dibasic. 485. 

glyoxylio, 481. 

hexabasio, 188. 

hydroxybenzoio, 482. 

laotio, 47^>. 



718 



INDEX. 



Acids, malic, 486. 
phthalic, 486. 
polybasic, 488. 
succinic, 486. 

table showing relations of acetic, 
lactic, and glycollic, 481. 

acetic and dibasic, 487. 

benzoic and hydroxybenzoic, 
482. 
tartaric, 486. 
tetrabasic, 488. 
tribasic, 488. 
trihydroxybenzoic, 484. 
Acidulous radicals, formula? and quan- 
tivalence of, 66, 122, 262. 
qualitative detection of, 364. 
quantitative estimation of salts 

of, 567. 
tables to aid in the detection of, 
366, 367. 
Acidum aceticum, 298. 

impurities in, 689. 
dihdum, 298. 
glaciate, 298, 689. 

impurities in, 689. 
arseniosum, 165. 
benzoicum, 335, 689. 
boricum, 333. 

impurities in, 689. 
carbolicum, 446, 689. 

crudum, 447. 
chromlcum, 236, 689. 
citricum, 323. 

impurities in, 682. 
gallicum, 359. 

impurities in, 690. 
hydrobromicum dilutum, 268. 

impurities in, 690. 
hydrochloricum, 29, 263. 

impurities in, 690. 

dilutum, 263. 
hydrocyanicum dilutum, 278. 

impurities in, 690. 
lacticum, 347. 

impurities in, 690. 
nitricum, 285. 

impurities in, 690. 

dilutum, 285. 
nitro-hydrochloricwm dilutum, 286. 
oleicum, 452. 

impurities in, 690. 
phosphoriciim, 329. 

dilutum, 329. 

impurities in, 691. 
salicylicum, 482. 

impurities in, 691. 
sulphuricum, 309. 

impurities in, 691. 
sulphuricum aromaticum, 309. 



Acidum sulphuricum aromaticum di- 
lutum, 309. 

sidphurosum, 305. 

impurities in, 691. 

tannicum, 357. 

impurities in, 691. 

tartaricum, 318. 
Acipenser, 534. 
Aconitia, 518. 
Aconiti ferocis radix, 519. 

folia, 518. 

heterophylli radix, 519. 
Aconitina, 518. 
Aconitine, 518. 
Acorin, 416. 
Acorus calamus, 416. 
Acrinyl sulphocyanate, 445. 
Acrolein, 450. 
Acrylic acid, 482. 

aldehyde, 450. 
Actea racemosa, 500. 
Adeps, 454. 

impurities in, 691. 

benzoinatus, 454. 
Adhesion, 56. 
Adraganthin, 469. 
JEgle marmelos, 358. 
Aerated bread, 461. 

water, 85. 
.ffisculin, 525. 
JSther, 440. 

impurities in, 691. 

aceticus, 403. 

impurities in, 691. 

fortior, 442. 

impurities in, 691. 

purus, 442. 
Affinity, chemical, 38. 
African pepper, 394. 
Agate, 354. 
Air, composition, 26. 

influence of animals and plants 
on, 19. 

relative Weight of the, 26, 605. 
Ajwain oil, 415. 
Alabaster, 104. 
Albumen, 530. 

detection of, in urine, 559. 

vegetable, 533. 
Albumen ovi, 530. 
Albumenoid substances, 530. 
Alchemy, 13. 
Alcohol, 434. 

absolute, 582. 

allylic, 452. 

amylic, 443, 582. 

benzylic, 449. 

butylic, 363. 

cinnamic, 485. 



INDEX. 



719 



Alcohol, decylene, 452. 

ethylic, 434. 

from sugar, 434. 

hydroxybenzylic, 350. 

in 100 parts of spirits of differ- 
ent densities, Table showing 
the proportion by weight of, 
711. 

methylic, 432. 

pentylic, 443. 

phenic, 446. 

prepargyl, 409. 

propenyl, 484. 

propylic, 443. 

quantitative estimation of, 684. 

test for impurities in, 628, 691. 

test for purity of, 438, 628. 
Alcoholates of bromal, 449. 

of chloral, 478. 
Alcoholometer, 601. 
Alcohols, allylic series, 444. 

benzylic, 447. 

dihydric, 458. 

hexhydric, 455. 

penhydric, 455. 

saleginin, 450. 

tetrahydric, 455. 

trihydric, 450. 
Aldehyde, 475. 

benzoic, 336. 

cumic, 414. 

euodic, 416. 

formic, 474. 

glycollic, 406. 

lauric, 416. 

orthohydroxybenzoic, 498. 

oxalic, 406. 

parahydroxybenzoic, 498. 

rutic, 415. 

salicylic, 404, 484. 

test for, 475. 
Aldehydes, 473. 
Ale, 436. 

Alexandrian senna, 491. 
Algaroth's powder, 178. 
Alizarate of potassium, 429. 
Alizarin, 427, 429. 
Alkalies, analytical separation, 100. 

antidotes to, 262. 

quantitative estimation of the, 
613. 
Alkalimetry, 619. 

Alkaline carbonates, volumetric esti- 
mation of the, 613. 

earths, 125. 

solution of arsenic, 165. 
Alkaloids, 500, 503, 553. 

animal, 503. 

vegetable, 503. 



Alkanet, 539. 
Alkanna tinctoria, 539. 
Allium, 445. 
Allotropes, 472. 
Allotropic bodies, 472. 
Allotropy, 472. 
Alloxan, 361. 
Alloy, 193. 
Allspice, 413. 
Allyl, cyanide, 445. 

sulphide of, 445. 

sulphocyanate of, 445. 
Allylene, 409. 
Allylic series of alcohols, 445. 

alcohol, 445. 
Almond oil, 455. 
Almonds, oil of bitter, 489. 

test for nitrobenzol in, 490. 
Aloes, pxirijicata, 430. 

socotrina, 430. 
Aloins, 445. 
Alstonia constricta, 524. 

scJwlaris, 524. 
Alstonicine, 524. 
Alstonine, 524. 
Althea, 481. 

officinalis, 470. 
Alum, 136. 

cake, 137. 

chrome, 137. 

dried, 138. 

flour, 136. 

iron, 137. 

potash, 136. 

roche or rock, 138. 

root, 359. 

soda, 137. 
Alumen, 136. 

impurities in, 692. 

exsiccatum, 138. 
Alumina, 138. 
Aluminii hydras, 138. 

impurities in, 692. 

sulphas, 137. 

impurities in, 692. 
Aluminium, 136, 712. 

analytical reactions of, 138. 

and ammonium sulphate, 137. 

and sodium, double chloride, 136. 

bronze, 136. 

derivation of word. 32. 

detection of, in presence of iron 
and zino, 160. 

hydrate, 137. 

oxide, 138. 

quantitative estimation of, 618. 

separation of, from ohromium and 
iron, 238. 

silicate. L37. 



720 



Aluminium sulphate, 137. 
Amalgam, 194. 

ammonium, 90. 
Amber, 355. 
oil, 355. 
American pennyroyal, 413. 
Amianth, 354. 
Amide, 203. 

Amido-chloride of mercury, 204. 
Amidogen, 203. 
Amines, 427. 
Ammonia, 91. 

detected by Nessler test, 615. 
fetid spirit, 93. 
gas, composition of, 91. 
in drinking waters, 615. 
preparation of, 91. 
solution of, 92. 
synthesis of, 91. 
volcanic, 90. 

volumetric estimation of solu- 
tions of, 614. 
Ammoniacal liquor, 90. 
salts, sources of, 90. 
Ammoniacum, 423. 
Ammonise {vide Ammonii). 
Ammoniated glycyrrhizin, 494. 
mercury, 203. 

varieties of, 203. 
Ammonii acetatus, liquor, 92. 
aqua, 92. 

fortior, 92. 
aromaticus, S2)iritus, 93. 
benzoas, 94, 336. 

impurities in, 692. 
bromidum, 94, 269, 626. 
impurities in, 692. 
volumetric estimation of, 626. 
carbonas, 92. 

impurities in, 93, 692. 
cTiloridtim, 90. 

impurities in, 692. 
eitratis, liquor, 94. 
foetidns, spiritus, 93. 
fortior, liquor, 92. 
iodidum, 94. 

impurities in, 692. 
nitras, 93. 

impurities in, 693. 
phosjihas, 94, 665. 

impurities in, 693. 
sulphas, 90. 

impurities in, 693. 
Valerianae, 363. 

impurities in, 693. 
Ammonio-chloride of mercury, 204. 
-citrate of iron, 152. 
-ferric alum, 137. 
-ferric sulphate, 137. 



Ammonio-magnesium phosphate, 120, 
331. 

-nitrate of silver, 175, 205. 

-sulphate of copper, 175, 205. 

-tartrate of iron, 153. 
Ammonium, 89. 

acetate, 92. 

amalgam, 91. 

analytical reaction, 97. 

and magnesium, arseniate of, 120. 

and magnesium phosphate, 120. 

and platinum, double chloride, 98, 
246. 

arseniate, 167. 

benzoate, 94, 336. 

bicarbonate, 92. 

bromide, 94, 269. 

carbamate, 92. 

carbonate, 94. 

solution of, 93. 

chloride, 90. 

citrate, 94. 

cyanate, 338. 

derivation of word/ 32. 

derivatives, 205. 

glycyrrhizate, 494. 

hydrate, 91. 

iodide, 272. 

molybdate, 331. 

nitrate, 93. 

oxalate, 95. 

periodide, 272. 

phosphate, 94. 

potassium and sodium, separation 
of, 100. 

quantitative estimation of, 644. 

salts, source of, 90. 
volatility of, 98. 

sulphate, 90. 

sulphide, 95. 

sulphydrate, 95. 

tartrate, 98. 

valerianate, 363. 

volumetric estimation of Carbo- 
nate of, 615. 
Amorphous, meaning of, 182. 

phosphorus, 330. 
Amphicreatinine, 504. 
Amygdala amara, 455 

dulcis, 455. 
Amygdalin, 489. 
Amyl, acetate, 403. 

nitrite, 405. 

impurities in, 693. 

valerianate, 405. 
Amylaceous substances, 463. 
Amylamine, 502. 
Amylene, 406. 

hydrate, 444. 



INDEX. 



721 



Ainylic alcohol, 443. 
Amyloids, 463. 
Ainyloses, 463. 
Amylum, 463. 

iodatum, 464. 
Ainyric acid, 423. 
Ainyrin, 423. 

Anacyclus pyretlirmn, 420. 
Analogies between chlorine, bromine, 
and iodine, 277. 

of sodium and potassium salts, 
88. 
Analogy of carbon, boron, and silicon, 
333, 355. 

of oxygen, sulphur, selenium, and 
tellurium, 301. 

of salts, 98. 
Analysis, 99. 

aided by sifting, 371. 

blowpipe, 372. 

gas, 360, 545. 

gravimetric, 577. 

meaning of word, 60. 

"organic, 669. 

practical, 99. 

proximate, 669. 

qualitative, 100. 

quantitative, 576. 

spectral, 539. 

systematic, for the detection and 
separation of the metals, 100, 
123, 184, 188, 221, 373. 

ultimate, 669. 

volumetric, 578, 611. 
Analysis and synthesis, 60. 

of gases and vapors, 544. 

insoluble salts, 373 et seq. 

salts, 370. 

substances having unknown prop- 
erties, 373. . 
Analytical chemists, 14, note. 

detection of the acidulous radi- 
cals of salts soluble in water, 
364. 

memoranda, 257, 262. 
Anamirta cocculus, 496. 

paiiiculata, 496. 
Anamirtin, 496. 
Anchasa tinctoria, 539. 
Anchusin, 539. 
Andria araroba, 3:58. 
Audrographis panicalata, 499. 
Andropogon citratw, 417. 

nardus, 413. 

schcenanthns, 414. 
Anemone pratensia, 335. 

])cttens, 335. 

Pulsatilla, 335. 
Anemunie acid, 335. 

61 



Anemonin, 335. 
Aneroid barometer, 579, 
Anethene, 412. 
Anethol, 412. 
Angelic acid, 412. 

powder, 178. 
Angelica, 412. 
Angustura-bark, 524. 
Anhydrides, 84. 
Anhydrous bodies, 84. 

nitric acid, 287. 

perchloride of iron, 144. 

sulphate of copper, 190. 
Aniline, 427,. 504. 

colors, 541. 
Animal charcoal, 110. 

decolorizing power of, 111. 

rouge, 337. 
Animals and plants, complementary, 

action of air, 19. 
Anise, 412. 
Aniseed oil, 412. 
Anise-fruit, 412. 
Anisum, 412. 
Annatto, 539. 
Anthemidis flores, 412. 
Anthemis, 4i2. 

nobilis, 412. 
Anthracene, 429. 
Anthracite, 238. 
Antidotes to acids, 262, 

alkalies, 262. 

alkaloids, 505. 

antimony, 183. 

arsenic, 149, 175. 

barium, 103. 

carbolic acid, 448. 

copper, 191. 

cyanides, 2S2. 

hydrochloric acid, 266. 

hydrocyanic acid, 2S2. 

lead, 212. 

mercury, 206. 

nitric acid, 290. 

oxalic acid, 316. 

silver, 217. 

sulphuric acid, 310. 

tin, 242. 

zinc, 135. 
Antifebrin, 514. 
Antimonial wine, ISO. 
Antimoniatc of potassium, S7. 

sodium, 87. 
Antimonic anhydride, 179. 

chloride, 178. 

oxide, 179. 
Antimonii cli/oridi, liquor, 178, 651. 

et potussii tartras, 179. 
impurities in, 693. 



722 



Antimonii et potassii tartras, quantita- 
tive estimation of antimony in, 
651. 

oxidant, 179. 

impurities in, 693. 

sulphidum, 177. 

purificatum, 177. 
impurities in, 693. 

sulphuratum, 180. 

impurities in, 693. 

vinum, 179. 
Antimonious anhydride, 179. 

chloride, 178. 

oxide, 178. 

oxychloride, 178. 
Antimonium sulphuratum, 180. 
Antimoniuretted hydrogen, 182. 
Antimony, 164, 177, 318, 584. 

analytical reactions of, 182. 

and arsenic, analytical separa- 
tion of, 185. 

and potassium tartrate, 189, 318. 

antidote to, 183. 

black, 177. 

butter, 178. 

chloride, 178. 

crude, 177. 

derivation of word, 32. 

from arsenic, to distinguish, 172. 

hydride, 182. 

in organic mixtures, detection of, 
547. 

oxide, 178. 

oxychloride, 178. 

oxysulphide, 180. 

pentaehloride, 178. 

potassio-tartrate, 179. 

quantitative estimation, 651. 

solution of chloride of, 178. 

sulphide, 177, 181. 

sulphur, salts of, 180. 

sulphurated, 180. 

tartrated, 179. 

volumetric estimation of, 629. 
Antipyrin, 514. 
Antiseptic, 448, 450, 483. 
Apocynum, 499. 
Apomorphine, 509. 
Apothecaries, 14. 
Apparatus, xi. 

for experiments, xi. 

for gravimetric analysis, 639, 648, 
653, 654, 659, 663, 669, 670, 672. 

for volumetric analysis, 611. 

list of, xi. 
Apple, acid in, 348. 

essence, 404. 

oil, 404. 

wine, 436. 



Aqua, 127. 

ammonise, 92. 

impurities in, 693. 
volumetric estimation of, 614. 
ammoniee fortior, 92. 

impurities in, 693. 
amygdalae amarse, 489. 
anisi, 412. 
aurantii fiorum, 412. 

impurities in, 693. 
camphorse, 418. 
chlori, 28,' 265. 
chloroformi, 399. 
cinnamomi, 412. 
destillata, 127. 

impurities in, 694. 
fceniculi, 412. 
fortis, 286. 
laurocerasi, 490. 
menthse piperitse, 412. 

viridis, 412. 
regia, 184, 287. 
rosse, 412. 
Arabin, 112. 
Arabinose, 459. 
Arachidic acid, 481. 
Arachis hypogsea, 456. 
Arachis oil, 456. 
Araroba powder, 337. 
Arbor Bianse, 217. 

vitee, 416. 
Arbutin, 359, 491. 
Archil, 540. 
Arctium lap>p)a, 500. 
Aretostaphylos uva-ursi, 491. 
Areca catechu, 359. 
Areca-nuts, 359. 
Arecoline, 359. 
Arekane, 359. 
Argal, 317. 

Argenti cyanidum, 217. 
iodidum, 217. 

impurities in, 694. 
nitras, 215, 656. 

gravimetric estimation of, 

656. 
dilutus, 216, 656. 
fusus, 216, 656. 
oxidum, 216, 656. 

impurities in, 694. 
Argentic chloride, sulphide, etc. (vide 

Salts of Silver). 
Argentiferous galena, 213. 
Argentum, 33. 

purificatum, 215. 
Argol, 317. 
Armenian bole, 539. 
Armoraciee radix, 412. 
Arnatto, 539. 



INDEX. 



723 



Arnica, 420. 
Arnicse radix, 420. 

flores, 420. 
Arnicin, 420. 
Arnotto, 539. 
Aromatio acids, 482. 

glycols, 449. 

series of hydrocarbons, 425. 
Arrow-root-starch (fig.), 465. 
Arseniate of ammonium, 167. 

barium, 175. 

calcium, 175. 

copper, 174. 

iron, 168, 633. 

magnesium and ammonium, 120. 

silver, 175. 

sodium, 167. 

zinc, 175. 
Arseniates, 167. 
Arsenic acid, 167. 

arsenical solutions, volumetric es- 
timation of official, 630. 

anhydride, 167. 

in carbonate of potassium, solu- 
tion of, 165. 

in hydrochloric acid, solution of, 
166. 

odor of, 166. 

white, 165. 

antidote to, 159, 175. 
Arsenical ores, 164. 

sulphur, 173. 
Arsenii iodidum, 164. 
Arsenicum, 164. 

analytical reactions of, 168. 

antidotes to, 149, 175. 

and antimony, analytical separa- 
tion of, 184. 

bromide, 164. 

chloride, 164. 

derivation of word, 32. 

detection of, in metallic copper, 
170. 
in ores, 175. 
in organic mixtures, 547. 

Fleitmann's test for, 172. 

from antimony, to distinguish, 
172. 

hydride, 171. 

iodide, 164. 

Marsh's test for, 170. 

quantitative estimation of, 630, 
650. 

red native sulphide, 165. 

reduction of arseniates to arse- 
nites, 167. 

Reinsch's test for, 170. 

sources of, 164. 

sulphido of, 165, 173. 



Arsenicum, yellow native sulphide, 

165. 
Arsenide of cobalt, 232. 
Arsenio-sulphide of iron, 164. 

of nickel, 234. 
Arsenious acid, 165. 

anhydride, 165. 

oxide, 165. 
Arsenites, 165. 
Arsenite of copper, 174. 

potassium, 165. 

silver, 174. 

sodium, 167. 
Arseniuretted hydrogen, 171. 
Art of Chemistry, 13. 
Artemisia absinthium, 414. 

maritima, 497. 
Artificial alkaloids, 501. 

gastric juice, 535. 
Asafcetida, 423. 
Asbestos, 354. 
Asclepedin, 499. 
Asclepias tuberosa, 499. 
Aselline, 456. 
Aseptol, 440. 
Asparagin, 349. 
Aspartate of ammonium, 349» 
Asp>idium, 456. 
Aspidospermine, 392. 
Atees, 392. 
Ateesine, 519. 
Atis, 392. 
Atmospheric pressure, measurement 

of, 568. 
Atom, definition of, 56. 

weights, definition of, 51. 
Atomicity, 53. 
Atomic proportions, 195, 198. 

theory, 50. 

weights, 51. 

relation of specific heat to, 
607. 
Atoms, 50, 51. 

quantivalence of, 55. 
definition of, 56. 
Atropa belladonna, 519. 
Atropia, tropate of, 51 9. 
Atropina, 519. 

impurities in, 694. 
Atropine sulphas, 519. 

impurities in, 694. 
Atropine, 519. 
Attar of rose, 415. 
Aurantii amari cortex, 413. 

dulcis cortex, 413. 

flores, 413. 
Auric chloride. 213. 

sulphide, _ 13. 
Ann' et sodii chloriduni, 244. 



724 



Auri et sodii chloridum, impurities in, 

694. 
A it rum, 34. 

impurities in, 694. 
Avogadro's and Ampere's law, 52, 53. 
Azadirachla indica, 500. 
Azedarach, 500. 
Azo, 504. 
Azobenzene, 427. 
Azoxybenzene, 427. 

Bacterium mycodermi, 296. 

Bael-fruit, 359. 

Bahia powder, 337. 

Baking-powder, 461. 

Balance, 585. 

Balloons, coal-gas for, 24. 

hydrogen for, 24. 
Balm, 415. 

Balm-of-Gi!ead fir, 423. 
Balsam, Canada, 423. 

copaiva, 422. 

fir, 414. 

Gurjun, 422. 

Peru, 419, 485. 

storax, 419, 485. 

Tolu, 419, 485. 
Balsamodendron myrrha, 424. 
Balsams, 419. 

Bahamian Peruvianum, 419, 485. 
impurities in, 694. 

Tolutanum, 419, 485. 
Baptin, 520. 
Baptisia tinctoria, 520. 
Baptism, 520. 
Baptitoxine, 520. 
Barbadoes aloes, 429. 
Barbaloin, 429. 
Barberry, 520. 
Barff's protected iron, 140. 
Barium, 102. 

acetonitrate, 125. 

analytical reactions of, 102. 

and calcium, separation of, from 
magnesium, 123. 

antidotes to, 103. 

arseniate, 103. 

carbonate, 103. 
native, 102. 

chloride, 102. 

chromate, 103. 
neutral, 103. 

derivation of word, 32. 

detection of, in presence of cal- 
cium and magnesium, 123. 

hydrate, 102. 

nitrate, 102. 

peroxide, 103. 

phosphate, 103, 331. 



Barium, oxalate, 103, 316. 

oxide, 103. 

quantitative estimation, 645. 

salts, antidote to, 103. 

silico-fluoride, 103. 

sulphate, 103. 

sulphide, 102. 

sulphite, 306. 
Barley-starch (fig.), 465. 

-sugar, 462. 
Barometer, 578. 
Baryta, 102. 

-water, 102. 
Basalt, 136. 
Base, meaning of, 260. 

organic, 379. 
Bassorin, 114, 469. 
Bastard saffron, 539. 
Basylous hydrocarbons, 391. 

radicals, 122. 
Bath brick, 354. 
Bauxite, 136. 
Bay, 414. 
Bay rum, 436. 

salt, 80. 
Bearberry, 359. 
Beaver tree, 500. 
Beberia or beberine, 520. 
Beberiss sulphas, 520. 
Beberine, 520. 
Beer, 436. 
Beeswax, 444. 
Beetroot, 460. 
Belse fructus, 358. 
BelladotDise folia, 519. 
Bell-metal, 239. 
Benne oil, 456. 
Benzaldehyde, 489, 490, 492. 
Benzaldehyde-cyanhydrin, 490. 
Benzene, 426. 

constitution of, 430. 

impurities in, 694. 

nitro-, 427. 

dinitro-, 427. 

disulphonie acid, 448. 

sulphonic acid, 440, 447. 

series of hydrocarbons, 425. 
Benzin, 431. 
Benzin-Collas,426. 
Benzine, 426. 

Benzoate of ammonium, 93, 336. 
Benzoated lard, 454. 
Benzoates, 335. 
Benzoic acid, 335, 581, 583. 

aldehyde, 335. 

glycocine, 336. 
Benzoin, 335, 419. 
Benzol, 426. 
Benzoline, 396. 



725 



Benzoyl chloride, 482. 

hydrate, 482, 522. 

hydride, 482. 

sulphonic imide, 440. 
Benzyl benzoate, 485. 

cinnamate, 485. 

hydrate, 485. 
Benzylic alcohol, 450, 485. 
Berbamine, 520. 
Berberia or berberine, 520. 
Bergamot oil, 413. 
Berlin blue, 539. 

red, 539. 
Berthollet's laws, 379. 
Beryllium, 712. 
Betaine, 503. 
Betel-nuts, 359. 
Betula lenta, 404. 
Bi-, the prefix, 71. 
Bibasic {vide Dibasic). 
Bibirine, 520. 
Bibulous paper, 107. 
Bicarbonate of ammonium, 91. 

of potassium, 70, 320, 324, 617. 
chemically pure, 618. 

of sodium, 82, 320, 324, 617. 
chemically pure, 618. 
Bicarbonates, test for, 314. 
Bichromate of potassium, 235. 
Bikh, 519. 
Bile, 537. 

detection of, in urine, 560. 

tests for presence of, 537. 
Biliary calculi, 573. 
Bish, 519. 
Bismuth, 248, 584, 653. 

and ammonium citrate, 251. 

analytical reactions of, 252. 

carbonate, 251. 

estimation of bismuth in, 

653. 
impurities in, 694. 

citrate, 251. 

derivation of word, 34. 

hydrate, 252. 

lozenge, 250. 

nitrate, 249. 

oxide, 251. 

oxysalts, 250. 

quantitative estimation of, 653. 

salts, composition of, 250. 

subcarbonate or oxycarbonato, 
251. 

subnitrate or oxynitrate, 249. 

sulphate, 251. 

impurities in, 694. 

sulphide, 252. 
Bisulphide of carbon, 312. 
Bisulphite of lime, 305. 



Bisulphite of sodium, 305, 631. 

Bitter almonds, oil of, 490. 

Bittern, 267. 

Bitter-sweet, 327. 

Bituminous coal, 238. 

Bivalence, 55. 

Bivalent radicals, 55, 122. 

Bixa orellana, 539. 

Bixin, 539. 

Blackberry, 359. 

Bladder-green, 540. 

Blanc de jjerle, 250. 

Blende, 129. 

Block tin, 239. 

Blood, 531, 568. 

detection of, in organic matter, 
569. 

hydrocyanic acid in the, 282. 
Blood-root, 527. 

vinegar, 297. 
Blood-stains, 569. 
Blowpipe analysis, 372. 
Boiled oil, 455. 

Boiling-points of various substances, 
582. 

-point, definition of, 582. 
Boldo, 413. 
Bonduc-seeds, 500. 
Bone-ash, 110. 

-black, 111. 

-earth, 326. 
Bone oil, 504. 

Bones, composition of, 326. 
Boneset, 500. 
Boracic acid, 33. 

anhydride, 333. 

as an antiseptic, 334. 
Borate of glyceryl, 334. 
Borates, 333. 

analytical reactions of, 334. 
Borax, 333. 

volumetric estimation of, 616. 

bead, 233. 
Bordeaux turpentine, 410. 
Boric acid (see Boracic acid), 333. 
Borneene, 416. 
Borneo camphor, 417. 
Borneol, 418. 
Boron, 333. 

chloride, 333. 

fluoride, 333. 
Borotartrate of potassium, 334. 
Bos taunts, 536. 
Bo8wellia, 424. 
Bourdon barometer, 579. 
Boylo's law, 52. 
Brandy, 436, 437. 
Brass, L29. 
Brasaica alba, 102. 



726 



Brassica nigra, 452. 
Br ay era, 421. 
Brazil-powder, 33S. 

-wood, 539. 
Bread, 461. 
Breidin, 423. 
Brezilin, 539. 
Bright's disease, 559. 
Britannia metal, 177, 207. 
British gum, 467. 
Broinal, 479. 

alcoholates of, 479. 

hydrate of, 479. 
Bromate of potassium, 76. 
Bromates, 270, 295. 

detection of, in bromides, 270. 
Bromic acid, 76, 295. 
Bromide of ammonium, 269, 626. 

arsenicum, 164. 

calcium, 269. 

ethyl, 400. 

iron, 145. 

lithium, 225. 

potassium, 75, 269, 626. 

volumetric estimation of, 
636. 

silver, 217. 

sodium, 269, 627. 

sulphur, 303. 
Bromides, 269. 

analytical reactions of, 269. 

quantitative analysis of, 626. 

separation of, from chlorides and 
iodides, 275. 
Bromine, 267. 

analytical separation of, 270. 

derivation of word, 33. 

its analogy to chlorine and iodine, 
271. 

solution of, 270, 

test of purity, 268. 
Bromum, 275. 

impurities in, 694. 
Bronze, 242. 

aluminium, 136. 

coinage, 188. 
Bronzing-powder, 242. 
Broom-tops, 528. 
Brucia, 517. 
Brucine, 517. 
Brunswick green, 174. 
Bryoidin, 422. 
Bryonia, 491. 
Bryonin, 491. 
Bryony, 491. 
Buchu, 413, 500. 
Buckthorn green, 540. 

-juice, 492. 
Bunsen gas-burners, 23. 



Burdock, 500. 
Burette, Mohr's, 612. 
Burgundy pitch, 421. 
Burners, gas, 17, 23. 
Burnett's disinfecting fluid, 131. 
Burnt ochre, 539. 
sugar, 462. 
umber, 541. 
Butane, 395. 
Butea frondom, 358. 
Butter, 454, 531. 

of antimony, 178. 

cacao, 454. 

cocoa, 454. 

kokum, 454. 

orris, 415. 
Butternut, 526. 
Butyl, chloral, 479. 
Butylene, 406. 
Butylic alcohol, 363. 
Butyrate of ethyl, 406. 
Butyrates, 363. 
Butyric acid, 363, 479. 
aldehyde, 479, 480. 
chlorinated, 479. 
Butyrone, 488. 
Buxine, 393. 
Buxus sempervirens, 393. 

Cabbage-rose petals, 538. 

oil of, 415. 
Cacao butter, 454. 
Cadaverine, 503. 
Cadmii iodidum, 248. 
Cadmium, 248. 

analytical reactions of, 248. 

carbonate, 248. 

derivation of word, 34. 

hydrate, 247. 

iodide, 248. 

nitrate, 248. 

sulphate, 248. 

sulphide, 248. 
Csesalpina braziliewsis, 539. 

bonducella, 500. 
Caesium, 712. 
Caffeina, 528. 

impurities in, 685. 
Cajuput oil, 413. 
Cajuputene, 413. 
Cajuputol, 413. 
Caking coal, 239. 
Calabar bean, 526. 
Calamine, 131, 416, 
Calamus, 416. 

draco, 420. 
Calcined magnesia, 119. 
Calcium,. 104. 

analytical reactions of, 114. 



727 



Calcium and barium, separation from 
magnesium, 123. 

bisulphite, 305. 

bromide, 269. 

impurities, 695. 

carbonate, 107. 
prepared, 109. 
impurities, 695. 

chloride, 104. 

impurities, 695. 

chromate, 114. 

citrate, 324. 

derivation of word, 32. 

flame, 114. 

fluoride, 104. 

in bones, 110. 

glycyrrhizate, 494. 

gummate, 113. 

hydrate, 106. 

hypochlorite, 112. 

hypophosphite, 343. 
impurities, 695. 

hyposulphite, 302. 

in presence of barium and mag- 
nesium, detection of, 123. 

oxalate, 114, 316. 

oxide, 105. 

phosphate, 104, 109. 

polysulphide, 302. 

quantitative estimation of, 646. 

silicate, 104, 354. 

sulphate, 104, 114, 302. 

sulphide, 113. 

sulphite, 305. 

superphosphate, 327. 

tartrate, 321. 
Calc-spar, 104. 
Calculi, urinary, 571. 

examination of, 571. 
Calendula, 500. 
Calendulin, 500. 
Calomel, 193, 200. 

test for corrosive sublimate in, 
200. 

tests for constituents of, 201. 
Galotropis, 500. 
Calumba, 520. 
Calx, 105. 

impurities in, 695. 

chlorata, 112. 

eulphurata, 113. 
Cambogia, 423. 

impurities in, 695. 
Camphor laurel, 417. 

oil, 417. 

-water, 418. 
Camphora, 417. 

cinnamomum, 417. 

monobromata, 417. 



Camphoretic acid, 418. 
Camphoric acid, 418. 
Camphors, 417. 
Cam-wood, 539. 
Canada balsam, 409, 423. 

pitch, 423. 
Canadian hemp, 499. 

moonseed, 520. 

turpentine, 409. 
Candle-flame, composition of, 23. 
Canellx albse cortex, 500. 
Cane-sugar, 460. 
Cannabene, 420. 

hydride of, 420. 
Cannabin, 420. 
Cannabis americana, 420. 

indica, 420. 
Cantharides, 418. 
Cantharidic acid, 418. 
Cantharidin, 418. 
Cantharis, 418. 
Caoutchouc, 417. 
Capacity unit, 588. 
Capillary, 580. 
Caproate of glyceryl, 454. 
Caproic acid, 454. 
Caprylate of glyceryl, 454. 
Cap ry lie acid, 454. 
Capsaicin, 522. 
Capsicin, 421. 
Capsicine, 522. 
Capsicum, 422, 522. 

fruit, resin of, 421. 

oil, 422. 
Caramel, 462. 
Caraway oil, 413. 
Carbamate of ammonium, 92. 

of ethyl, 479. 
Carbamic acid, 479. 
Carbamide, 479. 
Carbazotic acid, 448, 538. 
Carbinols, 432. 
Carbolic acid, 446. 

antidote to, 448. 
Carbo animalis, 110. 

purificatus, 111. 

impurities in, 695. 

ligni, 111. 
Carbolates, 448. 
Carbon, 30. 

bisulphide, 313. 

combustion of, 30. 

compounds. 3S2. 

derivation of word, 31. 

disulphide, 313. 

quantitative estimation o[\ in or- 
ganic compounds. 669 it Btq. 
Carbonate of ammonium, 91, 
solution of, 92. 



728 



Carbonate of barium, 103. 

bismuth, 250. 

cadmium, 247. 

calcium, 104, 106. 
prepared, 109. 

iron, 142, 634. 

saccharated, 143, 634. 

lead, 212. 

lithium, 224. 

magnesium, 117. 

potassium, 61. 

chemically pure, 618. 

sodium, 80, 87, 811, 617. 
chemically pure, 618. 
manufacture of, 87, 313. 

strontium, 226. 

zinc, 132, 135. 
Carbonates, 311. 

acidulous radical in, 311. 

analytical reactions of, 313. 

gravimetric estimation of, 663. 

volumetric estimation of alka- 
line, 617. 
Carbonei bisulphidum, 313. 
impurities in, 695. 
Carbonic acid, 30, 311. 

acid gas, generation of, 71. 
solubility of, in water, 85. 

anhydride, 311. 

oxide, 311, 337. 
Carbonization, 100. 
Carbonyl, 432. 
Carboxyl, 479. 
Carburetted hydrogen, heavy, 406. 

light, 394. 
Cardamon oil, 413. 
Cardamomum, 413. 

greater, 413. 

lesser, 413. 
Garica papaya, 536. 
Carmine, 337. 
Carminic acid, 337. 
Carnallite, 61. 
Carnine, 504. 
Carolina jasmine, 524. 
Carrageen moss, 470. 
Carrotin, 539. 
Carthamin, 539. 
Carthamus iinctorius, 539. 
Carui fructus, 413. 
Carum, 413. 

ajowan, 413. 
Carvene, 413. 
Carvol, 413. 
Caryophyllin, 413. 
Caryophyllus, 413. 
Cascara sagrada, 500. 
Cascarilla, 413. 

oil, 413. 



Cascarillin, 500. 
Casein, 531. 

vegetable, 533. 
Cassia acutifolia, 491. 

elongata, 491. 

fistula, 460. 

oil, 413. 
Castanea, 359. 
Castile soap, 453. 
Castilloa elastica, 417. 
Cast iron, 140, 584. 
Castor, 420. 

fiber, 420. 

oil, 456. 
Castoreinn, 420. 
Castorin, 420. 
Catecbin. 358. 
Catechu, 358. 

pallidum, 358. 
Catechuic acid, 358. 
Cathartic acid, 491. 
Cathartogenic acid, 491. 
Caulo])hylluin thalictroides, 500. 
Caustic, 215. 

alcohol, 437. 

lime, 105. 

lunar, 215. 

potash, 62. 

soda, 81. 
Cayenne pepper, 422. 
Cedra oil, 413. 
Cedrene,416. 
Celandine, 522. 
Celestine, 226. 
Cellulin, 470. 
Cellulose, 470. 
Celsius's thermometer, 580. 
Cements, 354. 
Centiare, 588. 

Centigrade thermometer, 580. 
Cepli&Us ipecacuanha, 524. 
Cera alba, 444. 

impurities in, 695. 
fiava, 444. 

impurities in, 695. 
Cerasin, 469. 
Cerasus serotina, 490. 
Cerates, 574. 

Ceratum pthimbi acetatis, 209. 
Cerebrin, 531. 
Ceresine, 444. 
Cerevisise fermentum, 434. 
Cerii oxalis, 227. 

impurities in, 695. 
Cerite, 227. 
Cerium, 228. 

derivation of word, 33. 

oxalate, 227. 
Ceroleine, 444. 



729 



Cerotic acid, 479. 
Ceryl-cerolate, 444. 
Cerylic alcohol, 444. 
Cetaceum, 444. 

impurities in, 696. 
Cetine, 444. 
Ceii-aria, 337. 
Cetraric acid, 337. 
Cetyl hydrate, 444. 
palinitate, 444. 
Cetylic alcohol, 444. 
Cevadilla, 529. 
Cevadilline, 529. 
Cevadine, 525, 529. 
Ceylon moss, 470. 
Chalcedony, 354. 
Chalk, 109. 

French, 541. 
precipitated, 107. 
prepared, 109. 
-stones, 571. 
Chalybeate-water, 140. 
Chameleon, mineral, 230. 
Chamomile oil, 412. 
Char, 100. 
Charcoal, 30. 
animal, 110. 

decolorizing power of, 111. 
wood, 111. 
Charles's law, 53. 
Charta sinapis, 445. 

potassii nitratis, 284. 
Chavica qffkinarum, 527. 
Chavicic acid, 527. 
Cheese, 531. 

Cheese-poison, 502, 556. 
Chelerythrin, 522, 527. 
Chelidonic acid, 522. 
Chelidonine, 522. 
Cheli doniitm, 522. 

Chemical action, definition of, 36, 40. 
by symbols, illustration of, 
41, 46. 
affinity, 38. 
combination, 38. 

by weight, laws of, 47, 58 et 

seq. 
by volume, laws of, 52 et 

seq. 
different from mechanical, 36, 

38. 
laws of, 47, 195, 285, 577. 
compound, 30. 

definition of, 57. 
diagram, 58, 63. 
equation, 58, 62. 
force, 37, 56. 

conditions for tho manifesta- 
tions of, 40. 



Chemical force, its relations to heat 
and electricity, 607. 

formula, definition of, 57. 

formulae, 42. 

notation, 41, 42. 

philosophy, principles of, 36 et 
seq. 

preparations of the Pharmaco- 
poeias, 574. 

symbol, definition of, 57. 

symbols, 31, 41, 42. 

toxicology, 545. 
Chemicals, 14. 

list of, xiv. 
Chemism, 38. 
Chemist and druggist, 14. 
Chemistry, art of, 13. 

and physics, differences between, 
46. 

definition of, 56. 

derivation of the word, 13. 

inorganic, 379. 

object of, 14, 48. 

organic, 379. 

science of, 13. 
Chemists, analytical, 14. 

consulting, 14. 

manufacturing, 14. 

pharmaceutical, 14. 
Chenopodium, 417. 

oil, 417. 
Cherry-laurel water, 490. 
Cherry, 323, 490. 

-tree gum, 469. 

wild black, 490. 
Chestnut, 359. 

-brown, 541. 
Chian turpentine, 409. 
Chili saltpetre, 284. 

nitre, 284. 
ChimapJiila, 491. 

umbellata, 491. 
China clay, 354. 
Chinese red, 539. 

wax, 444. 

white, 541. 

yellow, 53S. 
Chinoidin, 514. 
Chinoidinum, 514. 

impurities in, 696. 
Chinoline, 503. 
Chirata, 351. 
Chiratin, 351. 
Chiratogenin, 351. 
Chloral, 398, 476. 

alcoholates of, 476, 478. 

butyl, 479. 

oroton, 479. 

estimation of. 478. 



730 



INDEX. 



Chloral hydras, 477. 

impurities in, 696. 
hydrate, 477. 
Chlorate of potassium, 292. 

preparation of oxygen from; 
16. 
Chlorates, 291. 

analytical reactions of, 294. 
Chloric acid, 291. 
Chloride of ammonium, 89. 
antimony, 177. 
arsenicum. 164. 
barium, 102. 
boron, 333. 
calcium, 104. . 

removal of iron from, 105. 
chromium, 235. 
ethylene, 407. 
ethylidene, 407. 
gold, 244. 
iridium, 555. 
iron, 145. 
lead, 210. 
lime, 112. 
magnesium, 116. 
manganese, 228. 
mercuric ammonium, 204. 
mercurous ammonium, 204. 
mercury, 198. 
methyl, 526. 
palladium, 555. 
platinum, 245. 

and ammonium, 97, 246, 644. 
and lithium, 246. 
and potassium, 79, 246. 
and sodium, 190. 
silicon, 355. 
silver, 214. 
sulphur, 304. 
tin, 240. 

solution of, 240. 
zinc, 131. 
Chlorides, 263. 

estimation of, 657. 

separation of, from bromides and 

iodides, 274. 
tests for, 266. 
Chlorinated butyric alcohol, 479. 
lime, 112. 

volumetric estimation of, 638. 
soda, solution of, 86. 

volumetric estimation of, 
638. 
Chlorine, 27, 265, 657. 
acids, 294. 
as a disinfectant, 29. 
bleaching by, 28. 
collection of, 27. 
derivation of word, 31. 



Chlorine, its analogy to bromine and 
iodine, 270, 274. 

liquid, 265. 

preparation of, 27. 

properties of, 28. 

relative weight of, 29. 

solubility in water, 28. 

the active agent in bleaching- 
powder, 112. 

volumetric estimation of, 637. 

-water, 28, 265. 
Chlorochromic anhydride, 237. 
Chloroform, 401, 582. 

-water, 399. 
Chloroformum purificatum, 399. 
impurities in, 696. 

venale, 399. 

impurities in, 696. 
Chloronitric gas, 287. 
Chloronitrous gas, 287. 
Chlorophyll, 540, 575. 
Chlorous acid, 294. 
Chocolate, 454. 
Cholalic acid, 536. 
Cholate of sodium, 536. 
Cholesterin, 452, 573. 
Choline, 502, 536. 
Chondodendron tomentosum, 520. 
Chondrin, 534. 
Chondrus crispus, 470. 
Christmas rose, 495. 
Chromate of ammonium, 235. 

barium, 103. 

calcium, 114. 

lead, 212. 

mercury, 237. 

potassium and ammonium, 103. 

potassium, standard solution of 
red, 632. 

silver, 217. 
Chromates, 236. 

analytical reactions of, 237. 

of potassium, 103, 123, 237. 
Chrome alum, 236. 

ironstone, 235. 

-red, 212. 

-yellow, 212. 
Chromic acid, 236. 

anhydride, 236. 

hvdrate. 237. 

salts, 236. 
Chromium, 235. 

analytical reactions of, 238. 

chloride, 236. 

derivation of word, 33. 

separation of, from aluminium 
and iron, 238. 

sulphate, 236. 
Chromous salts, 23S. 



INDEX. 



731 



Chromule, 540. 
Chrysarumic acid, 430. 
Chrysarobine, 337. 
Chrysarobinum, 337. 

impurities in, 696. 
Chrysophanic acid, 337. 
Chyme, 535. 
Cicuta virosa, 414. 
Cider, 436. 

Cimicifuga racemosa, 500. 
Cimicifugin, 500. 
Cinchamidine, 515. 
Cinchona assay, 674. 
Cinchona calisaya, 510. 

fiava, 510. 

officinalis, 510. 

pallidse cortex, 510. 

rubra, 510. 

8iiccir ubra, 515. 
Cinchonicine, 515. 
Ginchonidinse sulphas, 514. 

impurities in, 696. 
Cinchonidine, 514. 
Cinchonina, 514. 

impurities in, 696. 
Cinchoninse sulphas, 514. 
Cinchonine, 514. 
Cinnabar, 192. 
Cinnamein, 485. 
Cinnamene, 485. 
Cinnamic acid, 337, 485. 

alcohol, 485. 

aldehyde, 413. 

series ^of acids, 485. 
Cinnamol, 485. 
Cinnamomum, 413. 
Cinnamon oil, 413. 
Cinnamyl, cinnamate of, 485. 
Citrate of ammonium, 93. 

calcium, 321. 

iron, 152. 

and ammonium, 252. 
and strychnine, 152. 
and quinine, 152, 678. 

lithium, 224. 

magnesium, 119. 

nicotia, 526. 

potassium, 72. 

volumetric estimation of, 617. 

quinine, 511. 

silver, 325. 
Citrates, 72, 323. 

analytical reactions of, 325. 

volumetric estimation of, 617, 618. 
Citrenes, 409. 
Citric acid, 323. 

action of heat on, 324. 

saturating power of, 324. 
Citrine ointment, 197. 



Citronella oil, 414. 

Citronellol, 414. 

Citro-tartrate of sodium, 86. 

Citrus, 409. 

Citrus bergamia, 323. 

Classification of elements, 100, 122, 

122, 256. 
Clausius's theory, 24. 
Claviceps purpurea, 420. 
Clay, 136. 

ironstone, 140. 
Cloves, oil of, 413. 
Club-moss, 456. 
Coal, 239. 

products of, 447, 541. 
Coal-gas, 448. 

for balloons, 23. 

-tar colors, 541. 
Cobalt, 232. 

analytical reactions of, 232. 

arsenide, 232. 

blue, 540. 

derivation of word, 33. 

-glance, 232. 

hydrate, 232. 

separation of, from nickel, 234. 

sulphate, 232. 

sulphide, 232. 
Cobaltic ultramarine, 540. 
Cobalticyanide of potassium, 233. 

of nickel, 233. 
Cobalticyanides, 238. 
Coca, 522. 
Cocaidine, 522. 
Cocaina, 522. 
Cocaine, 522. 
Cocamine, 522. 
Coccerin, 337. 
Cocculus indicxis, 496. 
Coccus, 337. 

ilicis, 180. 

impurities in, 696. 
Cochineal, 337. 
Cocoa, 454. 

-butter, 454. 

-nibs, 454. 

-nut, 454. 

-nut oil, 454. 
Cocoatina, 454. 
Cocos nuci/era, 454. 
Codamine, 507. 
Codeia or codeine, 507. 
Codeina, 507. 

impurities in, 696. 
Cod-liver oil, 455. 
Cohesion, 56. 
Coinage, copper, 188. 

gold. 243. 

silver, 214. 



732 



Coke, 30. 
Colchicein, 522. 
Colchicia, 522. 
Colchici cornus, 522. 

radix, 522. 

8emina, 522. 
Colchicin, 522. 
Colchicine, 522. 
Colcothar, 539. 
Collection of gases, 16, 17. 
Collidine, 503, 520. 
Collin, 685. 
Collodion, 471. 
Collodiiim, 471. 

flexile, 471. 

stypticum, 471. 

vesicans, 471. 
Cologne-water, 412. 
Colloid bodies, 685. 
Colocynthin, 492. 
Colocyntliis, 492. 
Colophene, 410. 
Colopholic acid, 419. 
Colophonic acid, 419. 

hydrate, 419. 
Colophonine, 419. 
Colophony, 419. 
Coloring-matters, 538. 
Combination, chemical, 44, 46. 

by volume, 52. 
Combining proportions, 48, 195, 285, 

577, 639. 
Combustible, 22. 
Combustion, 22. 

analysis for carbon and hydro- 
gen, 669 et seq. 
for nitrogen, 672. 

definition of, 57. 

spontaneous, 155. 

supporters of, 22. 
Composition of atmosphere, 26. 

bismuth salts, 251. 

centesimal, 386. 

empirical, 386. 

molecular, 386. 

oils and fats, 451. 

organic compounds, 384. 
Compound, chemical, 37. 

different from mechanical, 36. 
definition of, 57. 
Compounds, 13, 36. 

of the elements, 60. 
Conchinine, 513. 
Condensation, 126. 
Condenser, 126. 
Condensing-tub, 126. 

-worm, 126. 
Condy's disinfecting fluid, 76, 229. 
Confections, 574. 



Conhydrine, 523. 

Conia, conine, or conicine, 522, 523. 
Conium maeidatum, 522. 
Conquinine, 513. 
Constant proportions, law of, 47. 
Constant white, 541. 
Constitution of alkaloids, 503, 509, 
514. 

benzene series, 428. 
matter, 41. 

of organic compounds, 387. 

salts, 52, 121, 261, 284, 298, 379, 
390, 394. 

visible matter, 30, 42. 
Constitutional formulas, 386. 
Construction of formulas, 42, 45, 62, 

63. 
Convolvulin, 495. 
Convolvulinol, 495. 
Convohndus scammonia, 498. 
Conylia, 522. 
Copaiba, 422. 

impurities in, 422, 696. 
Copaiva, 422. 

oil, 414. 
Copaivic acid, 422. 
Copaivaol, 422. 
Copal, 420. 
Copper, 188. 

acetate, 190. 

ammonio-sulphate, 175, 191, 204. 

analytical reactions of, 190. 

antidotes to, 191. 

arseniate, 174. 

arsenical, 170. 

arsenite, 174. 

black oxide, 189. 

blue, 540. 

coinage, 188. 

derivation of word, 32. 

detection of arsenicum in, 174. 

foil, 189. 

hydrate, 191. 

iodide, 273. 

in organic mixtures, detection of 
547. 

melting-point of, 584. 

metallic, 189. 

oxide, 189. 

oxyacetate, 190. 

pyrites, 188. 

quantitative estimation of, 652. 

quantivalence of, 188. 

subacetate, 190. 

sulphate, 189. 

anhydrous, 190. 

sulphide, 190. 
Copperas, blue, 142. 

green, 142. 



INDEX. 



733 



Coptis trifolia, 520. 
Coriander oil, 414. 
Coriandrum, 414. 
Cork, sp. gr. of, 604. 

-borers, 16. 
Cornic acid, 338. 
Cornin, 338. 
Corn-smut, 420. 
Comas, 338. 

florida, 338. 
Cornutene, 420. 
Corpse-fat, 534. 

Correction of the volume of a gai 
pressure, 604. 

for temperature, 604. 
Corrosive sublimate, 199, 203. 

test for, in calomel, 200. 
Cortex pruni serotinse, 490. 
Corydalia, 523. 
Corydalina, 523. 
Cotarnine, 507. 
Coto-bark, 492. 
Cotoin, 492. 
Cotton-root bark, 420. 

-seed oil, 455. 

-wool, 470. 
Couch-grass, 500. 
Coumarin, 484. 
Cowbane, 414. 
Cowhage, 239. 
Cow's milk, 532. 
Cranesbill, spotted, 359. 
Cream, 532. 

of tartar, 318. 
Creasol, 447. 
Creasote, 447. 
Creasotum, 447. 

impurities in, 696. 
Creatine, 504. 
Creatinine, 504. 
Cremnitz white, 541. 
Cresol, 447, 449. 
Crcsotic acid, 483. 
Cresylic acid, 447. 
Creta ^>r#yH< >•«£«, 109. 

impurities in, 696. 
Crinum asiuticum, 498. 
Crocetin, 538. 
Crocus (mineral), 150. 

(vegetable), 538. 
Crocus sutivus, 538. 
Croton chloral, 479. 

hydrate, 479. 

oil, 455. 
Crotonylene, 409. 
Crucibles, 68. 
Crude antimony, 177. 

potashes, 61. 
Cruui's test for manganese, 231. 



Cruso-creatinine, 505. 
Cryohydrates, 85. 
Cryolite, 377. 
Cryptopia, 507. 
Crystallization, water of, 84. 
Crystalloid bodies, 685. 
Cubeb pepper, 527. 
Cubeba, 527. 
Cubebene, 414. 
Cubebin, 527. 
Cubebs, oil of, 414. 

oleoresin, 422. 
Cubic inches in one gallon, 605. 
Cubic nitre, 284. 
Cuca (see Coca). 
Cucurbita pepo, 500. 
Culver's root, 500. 
Cumin, 414. 
Cuminic acid, 414. 
Cuminol, 414. 
Cuminum, 414. 

cy minimi, 414. 
Cummin, 414. 
Cupel, 657. 
Cupellation, estimation of silver by, 

657. 
Cupreine, 515. 
Cupri acetas, 190. 

impurities in, 696. 

sulphas, 189. 

impurities in, 697. 
Cupric arsenite, 174, 191. 

compounds, 190. 

ferrocyanide, 191. 

hydrate, 191. 

oxide, 189. 

sulphate, 189. 

sulphide, 189. 
Cuprous iodide, 189, 274. 

oxide, 189. 
Cuprum ammoniatum, 191. 
Curacoa, 436. 
Curari, 517. 
Curarine, 517. 
Curcuma longa, 538. 
Curcumin, 538. 
Curds, 462, 531. 

and whey, 462, 531. 
Curd-soap. 453. 
Currant, 323. 348. 
Curry-powder, odor and flavor of. 416. 

Cuxjmri.T carter, 523. 
Cusparine, 523. 
Cutch, 358. 
Cyanates, 338. 
Cyanic acid, 338. 
Cyanide of allyl, I 15. 

mercury, 278. 

nickel, '23 I. 



734 



Cyanide of potassium, 278. 

silver, 217. 
Cyanides, 277. 

analytical reactions of metallic, 
281. 

antidote to, 282. 

double, 278. 

quantitative estimation of. 625. 
Cyanog-en, 278, 2S2. 
Cyanurets (vide Cyanides). 
Cydonium, 470. 
Cymene, 410, 414, 425, 42S. 
Cymol, 414. 

Cypripedium pubescens, 500. 
Cystin, 565. 

Dahlia, 467. 

Dalton's atomic theory, 51. 

law, 48, 49. 
Dandelion, 467. 
Daphne la areola, 421. 

mezereum, 421, 492. 
Daphnetin, 492. 
Daphnin, 492. 
Datura alba, 525. 

stramonium, 525. 
Daturia or daturine, 525. 
Dauglish's bread, 461. 
Davy's safety-lamp, 23. 
Deadly nightshade, 519. 
Decantation, 108. 
Decimal coinage, 587. 

weights, 587, 590. 
Decoctions, 574. 

Decolorizing power of animal char- 
coal, 111. 
Decrepitation, 372. 
Deevlene alcohol, 445. 
Deflagrating flux, 377. 
Deflagration, 74. 
Deliquescence, 87. 
Delphine alcohol, 524. 
Denarcotized opium, 506. 
Density, 599. 

of vapors, 605. 
Deodorizers, 29. 
Deodorizing liquid, 131. 
Deposits, urinary, 564, 565. 
Derivation of names of elements, 31 

et seq. 
Derivatives of ammonium, 204. 
Desiccation, 641, 664. 
Destructive distillation, 127. 
Detonation, 74. 
De Valangin's solution, 166. 
Dextrin, 467. 

maltose, 469. 
Dextrogyrate, 460. 
Dextro-racemic acid, 319. 



Dextrose, 458. 

Dextro-tartaric acid, 319. 

Dhak tree, 358. 

Dhatura, 525. 

Diabetic urine, 559. 

Diagram, chemical, definition of, 57. 

Diagrams, chemical, 46, 47, 63, 64, 65, 

69. 
Dialvsate, 6S5. 
Dialysis. 685. 
Dialytic iron, 686. 
Dialyzed iron, 685. 
Diamines, 502. 
Diamond, 29. 
Diastase, 468. 
Dibasic acids, 261. 
Dibasylous radicals, 261. 
Diazobenzene, 503. 
Dibrom-ethane, 406. 
Dicentra formosa, 524. 
Dichloromethane, 39S. 
Dichloromethylbenzene, 428. 
Dichopsis gutta, 417. 
Didymium, 712. 
Dietetics, 14. 
Diethylia, 493. 
Diethylamine, 501. 
Diffusate, 6S5. 
Diffusion, 24. 

law of, definition of, 57. 
Digitalein, 493. 
Digitalin, 492. 
Digitalinum. 492. 
Digitaliretin, 492. 
Digitalis, 492. 
Digitin, 493. 
Digitonin, 493. 
Digitoxin, 493. 
Dihydric alcohols, 406, 449. 
Dihydroxyl derivatives of the hydro- 
carbons, 449. 
Dihydroxylbenzenes, 449. 
Dihvdroxvsuccinic acid, 486. 
Dill' oil, 422. 

Dimethyl-ethyl-carbinol, 443. 
Dinitrobenzene, 427. 
Dinitrobenzol, 426. 
Dinitrocellulin, 470. 
Diosphenol, 413. 
Dinspyros embryopteris, 359. 
Dipterocarpi balsamum, 422. 
Dipteroca/pus Isevis, 422. 

turbinatis, 422. 
Disinfectant, chlorine as a, 29. 
Disinfectants, 29. 
Disinfecting fluid, Burnett's, 131. 

carbolic acid, 44S. 
Condy's, 76, 227. 

powder, 112. 



735 



Dissociation, 607. 
Distillation, 125. 

destructive, 127. 

dry, 127. 
Distilled vinegar, 297. 
Disulphide of carbon, 313. 
Dita, 521. 
Ditain, 524. 
Ditamine, 524. 
Dithionic acid, 346. 
Dock, 337. 
Dolomite, 116. 
Donovan's solution, 164. 
Dorema ammoniacum, 423. 
Double chloride of aluminium and 
sodium, 136. 

cyanides, 278. 

salts, 78. 
Doundake, 420. 
Dover's powder, 524. 
Drachm, 595. 
Draconyl, 485. 
Dragon's blood, 420. 
Dried alum, 138. 
Drops, 595. 
Dry distillation, 127. 
Drying apparatus, 641, 644. 

oils, 455. 

precipitates, 639, 641, 646, 664. 
Dryobalanops aromatica, 418. 
Duboisia, 525. 

myroporoides, 525. 
Dulcamara, 527. 
Dulcamariri, 527. 
Dulcite, 456. 

Dulong and Petit's law, 607. 
Dyads, 122. 
Dyer's saffron, 539. 
Dyeing, 138, 289. 

by mordants, 138. 
Dynamic electricity, production of, 

130. 
Dynamicity, 56. 
Dynamite, 451. 

Earth, alkaline, 125. 

bone-, 110. 

-nut oil, 456. 
Earthenware, 351. 
Eau-de-Cologne, 412. 
Ebonite, 417. 
Ebullition, 279. 
Ecballinm elat&'hm, 493. 
Ecboline, 420. 
Eehites scholar is, 521. 
Elllorcscence, 87. 
Egg, oil of, 530. 

white of, 530. 

yolk of, 530. 



Elseometer, 601. 
Elaaoptens, 411. 
Elaidic acid, 480. 
Elaterinum, 493. 

impurities in, 697. 
Elaterium, 493. 
Elder-flower oil, 416. 
Elecampane, 414. 

Electricity, production of dynamic, 
130. 

related to chemical action, 608. 
Elementary particles, 37. 
Element, definition of, 57. 
Elements, 13, 14, 30. 

and their compounds, 60. 

classification of, 100, 122, 125, 256. 
according to analogy, 100. 
according to quantivalence, 
121. 

etymology of names of, 31. 

of medical or pharmaceutical in- 
terest, 14. 

metallic, 15. 

non-metallic, 15. 

of pharmaceutical interest, 14. 

symbols of, 31, 46. 

atomic values and weights of 

the, 712. 
and derivation of names of 
the, 31 et seq. 
Elemi, 422. 
Elixirs, 574. 
Elm, common, 407. 

mucilage, 470. 

slippery, 470. 
Elutriation* 132. 
Emetia, 524. 
Emetine, 524. 
Empirical formulas, 386. 
Emplastra, 574. 
Emplastrum plumbi, 211. 
Emulsin, 489. 
Emulsion, 424, 452. 
Enemas, 574. 
English red, 539. 

blue, 540. 
Epsom salt, 116. 

Equation, chemical, definition of, 58. 
Equations, 58. 
Equisetic acid, 324. 
Equivalence, 56. 
Equivalents, 712. 
Erbium, 712. 
Ergosterin, 420. 
Ergot, 420, 
Err/ola, 121. 
Ergotin, 420. 
Ergotine, 120. 
Ergotiuino, 120. 



736 



INDEX. 



Ergotinic acid, 420. 
Ericolin, 491. 
Erigeron canadense, 414. 
Erlangen blue, 540. 
Erucic acid, 456. 
Erythrite, 486. 
Erythroretine, 337. 
Erythroxylon, 522. 

<-oca, 522. 
Esculin (see JEsculin). 
Eseridine, 526. 
Eserine, 526. 
Essence of aniseed, 412. 

apple, 404. 

greengage, 404. 

melon, 404. 

mirbane, 426. 

mulberry, 404. 

peppermint, 412. 

pineapple, 404. 

quince, 404. 
Essences, 412. 
Essentia anisi, 412. 

menthse piperita, 412. 
Essential oils (vide Oils). 
Ester, 474. 

Estimation of weight, 585. 
Etching, 342. 
Ethal, 444. 
Ethane, 395. 

substitution-products of, 400. 
Ether, 440. 

acetic, 488. 

hydrobromic, 400. 

nitrous, 400. 

petroleum, 396. 
Etbereal salts, 404, 474. 
Etherol, 406. 
Ethers, 439, 474. 
Ethiops mineral, 205. 
Ethyl, acetate, 488. 

bromide, 400. 

butyrate, 404. 

carbamate, 480. 

group, 428. 

hydrate, 431. 

hydride, 395. 

hydrogen sulphate, 434, 441. 

iodide, 400. 

nitrite, 351, 400. 

cenanthylate, 404. 

oxide, 404. 

pelargonate, 404. 

sebacetate, 404. 

suberate, 404. 

sulphuric acid, 441. 

zinc, 395. 
Ethylate of sodium, 438. 
Ethylene, 406. 



Ethylic alcohol, 434. 

bromide, 400. 

iodide, 401. 

series of alcohols, 431. 
Ethylphenuene, 425. 
Ethylsulphonic acid, 439. 
Ethylsulphuric acid, 441. 
Etymology of names of elements, 31. 
Eucalyptol, 414. 
Eucalyptus, 414. 

globulus, 414. 
Euchlerine, 294. 
Eudiometry, 544. 
Eugenic acid, 413. 
Eugenin, 413. 
Euodic aldehyde, 415. 
Euonymin, 500. 
Euonymus atropurpureus, 500. 
Eupatorium., 500. 
Euphorbium, 423. 
Euphorbon, 423. 
Euxanthate of magnesium, 538. 
Evaporation, 70, 100, 641. 

in vacuo, 641. 
Everitt's yellow salt, 280. 
Examinations of the Pharmaceutical 
Society of Great Britain, 14 
(vide prefatory matter). 
Expansion on diluting solution of am- 
monia, 91. 
Explosion of gases, 22. 
Extract of malt, 469. 
Extracts, 574. 

Extraction glycyrrhizpc, 494. 
fiuidum, 494. 
purum, 494. 

Satitrni, 309. 

Face-rouge, 337. 
Fahrenheit's thermometer, 580. 
Farina tritici, 463. 
Fat-acids, 452. 

Fats and oils, composition of, 451. 
Fats, etc., to determine the melting- 
point of, 583. 
Fatty acids, 452. 
'bodies, 451. 
Feces, 557. 

Fehling's solution, 681. 
Eel bovis, 536. 

inspissatum, 536. 

purification, 536. 

impurities in, 697. 
Felspar, 377. 
Fennel oil, 414. 
Fenugreek, 529. 
Fermentation, 435. 

alcoholic, 436. 

ammoniacal, 435. 



INDEX. 



737 



Fermentation, butyric, 435. 
lactic, 435. 
mannitic, 435. 
putrefactive, 435. 
viscous, 435. 
Fer reduit, 156. 
Ferrate of potassium, 141. 
Ferri acetatis, liquor, 148. 
tinctura, 148. 
arsenias, 143. 
bromidi, syrupus, 145. 
carbonas, 142. 

saccharatus, 143. 

impurities in, 697. 
chloridi, liquor, 147. 
chloridum, 147. 

impurities in, 697. 
citras, 152. 
citratis, liquor, 152, 
et ammonii citras, 152. 

impurities in, 697. 
quantitative estimation 

iron in, 649. 
sulphas, 137. 

impurities in, 697. 
tartras, 153. 

impurities in, 697. 
et potassii tartras, 152, 322. 
impurities in, 697. 
et quininse citras, 152. 

impurities in, 697. 
liquor, 153. 
et strychuinse citras, 152. 

impurities in, 697. 
hypophosphis, 344. 

impurities in, 697. 
iodidum saccharatum, 145. 

impurities in, 697. 
lactas, 348. 

impurities in, 697. 
nitratis, liquor, 155. 
ox alas, 315. 
oxidum hydratum, 148. 
cum magnesia, 149. 
perchloridi, liquor, 146. 
jjeroxidum hydration, 149. 
phosphas, 144, 153. 
potassio-tartras, 152. 
pulvis, 156. 
pi/rophosphas, 157. 
submlphatis, liquor, 148. 
sulphas, 141, 635. 

impurities in, 697. 
exsiccatus, 242. 
prsecipitatis, 142. 

impurities in, 697. 
tersu/phatus, liquor, 14S. 
valarianas, 363. 
Ferric acetate, 148. 



Ferric chloride, 145. 

citrate, 152. 

hydrate, 149. 

hypophosphite, 344. 

iodate, 295. 

nitrate, 154. 

oxide, 150. 

from phosphates and ox- 
alates, separation of, 375. 

oxyiodate, 295. 

oxysulphate, 142. 

peroxyhydrate, 149. 

phosphate, 153, 331. 

pyrophosphate, 157. 

salts, 145. 

analytical reactions of, 157. 

sulphate, 148. 

sulphocyanate, 159. 

tartrate, 153. 

valerianate, 363, 
Ferricyanide of potassium, 159, 278, 

341. 
Ferricyanides, 341. 
Ferricyanogen, 159, 341. 
Ferrocyanide of potassium, 159, 278, 
341. 

of zinc, 135. 
Ferrocyanides, 340. 
Ferrocyanogen, 159, 341. 
Ferroso-ferric hj'drate, 153. 

oxide, 154. 
Ferrous arseniate, 143, 634. 

bromide, 145. 

carbonate, 143, 634. 

chloride, 147. 

hydrate, 158. 

iodide, 145. 

phosphate, 144. 

salts, 141. 

analytical reactions of, 157. 

sulphate, 141, 635. 

sulphide, 144, 157. 
Ferrum, 32, 140. 

redaction, 156, 650. 

impurities in, 697. 

tartaration, 322. 

estimation of iron in, 649. 
Ferulaic acid, 423. 
Fibrin. 531. 

vegetable, 533. 
Ficus, 45S. 

elastica, 417. 
Fig, 458. 
Filicic acid, 456. 
Filter, to dry, 640. 
Filtering paper, 107, 639. 
Filters, 107. 640. 
Filtrate. L23. 
Fine gold, 2 13. 



738 



Fireclay, 199. 
Fire-damp, 394. 
Fir wool, 410. 

oil, 410. 
Fixed and volatile oils, difference be- 
tween, 455. 
Fixed oils, 455. 
Flag, blue, 500. 
Flame, structure of, 23. 
Flashing-point, 410. 
Flaxseed, 470. 
Fleabane, 414. 

Fleitmann's test for arsenicum, 172. 
Flexible collodion, 471. 
Flint, 354. 
Flores zinci, 133. 
Flour, 463. 

Flowers of sulphur, 300. 
Fluid magnesia, 118. 
Fluoride of boron, 332. 

calcium, 104. 

in bones, 110. 

silicon, 343. 
Fluorides, 342. 
Fluorine, 343. 

derivation of word, 33. 
Fluor-spar, 343. 
Fceniculum, 414. 
Foenugreek, 529. 
Foil, copper, 189. 
Food, analysis of, 686. 

elements of, 533. 

how disposed of in the bodies of 
animals, 533. 
Force, chemical, 37. 
Forge-scales, 1 54. 
Formates, 339. 
Formic acid, 338. 
Formica rufa, 338. 
Formula, chemical, definition of, 57. 

official, 28. 

officinal, 28. 
Formulae, 42, 45, 673. 

constitutional, 386. 

construction of. bo, 63. 

empirical, 386, 673. 

graphic, 136. 

rational, 386, 673. 
Fousel oil, 443. 
Fowler's solution, 165. 
Foxglove, 492. 
Fractional distillation, 435. 
Frangula, 492. 
Frankincense, Arabian, 424. 

common, 424. 
Fraxinus ornus, 457. 
Free acids, : J .69. 

estimated, 620. 
Freezing-mixture, 304. 



French chalk, 541. 

turpentine, 409. 
Fruit-essences, 404. 
Fuchsine, 541. 
Fulminating mercury, 216. 

silver, 216. 
Fume-cupboard, 100. 
Fuming sulphuric acid, 309. 
Funnel-tubes, 23, 96. 
"Fur" in water-vessels, 314. 
Furniture of a laboratory, xiii. 
Fusel oil, 443. 

Fusibility of metals, Table of the, 584. 
Fusible white precipitate, 203. 
Fusing-points of fats, 583. 
Fustic, 538. 

Gab tree, 359. 
Gadinine, 502. 
Galactometer, 601. 
Galactose. 460, 462. 
Galbanum, 423. 
Galena, 207. 

argentiferous, 213. 
Galenical preparations of the British 

Pharmacopoeia, 574. 
Galipot, 419. 
Gall, of the ox, 536. 
Galla, 357. 
Gallic acid, 359. 
Gallium. 712. 
Gallon, 5S7 
Gallotannic acid, 4S4. 
Galls, Aleppo, 357. 

English, 357. 
Gall-stones. 573. 
Galvanic test for mercury, 206. 
Galvanized iron, 129. 
Gambier, 35S. 
Gamboge, 423. 
Gambogic acid, 423. 
Garancin. 539. 
Garcinin Havburii, 423. 

iudica, 454. 
oil, 454. 

morella, 423. 

pictoria, 423. 

purpurea, 454. 
Garden thyme, 414. 
Garlic, essential oil of. 445. 
Gas, a, definition of, 58. 

analysis, 360, 544. 

-burners, 16, 23. 

for balloons, coal-, 23. 

-lamp, 18, 23. 
Gases and vapors, density of, 579, 605. 

collection of, 16, 19. 

correction of the volume of, 605. 
for pressure, 605. 



739 



Gases, correction of the volume of, 
for temperature, 605. 

diffusion of, 24. 

law of solubility of, in liquids, 85. 

relation of, to liquids and solids, 
43, 44. 

specific gravity of, 605. 
Gastric juice, 535. 

artificial, 535. 
Gaulthen'a procumbeiis, 404. 
Gaultheric acid, 404. 
Gay-Lussac's law, 52. 
Gelatigenous substances, 534. 
Gelatin, 534. 

sugar, 536. 

vegetable, 470. 
Gelatinized starch, 463. 
Gelseminia, 524. 
Gelseminic acid, 524. 
Gelsemium, 524. 
Gentian-bitter, 494. 
Gentiana lutea, 494. 
Gentianse radix, 494. 
Gentianic acid, 494. 
Gentiogenin, 494. 
Gentiopicrin, 494. 
Gentisic acid, 494. 
Gentisin, 494. 
Geraniol, 414. 
Geranium maculatum, 359. 
German silver, 233. 
Gin, 437. 
Gingelly oil, 456. 
Ginger oil, 417. 

-grass oil, 414. 
Girdwood and Rogers's method for 

detecting strychnine, 552. 
Glacial acetic acid, 298, 583. 

phosphoric acid, 330. 
Glass, 354. 

liquor, 355. 

rods, 108. 

soluble, 355. 

tubes, to bend, 17. 
to cut, 17. 
to draw out, 108. 
Glauber's salt, 265. 
Globulin, 531. 
Glucinum, 712. 
Glucose, 458. 
Glucosides, 489. 
Glue, 531. 

Gluten and glut in, 463. 
Glyceric alcohol, 431. 
Glycerin, 209, 211, 431, 449. 
Glycerins, 451. 
Glycerinnm, 151. 

impurities in, 697. 
Glyceritnm, 451. 



Ghjceritum amyli, 451. 

vitelli, 451. 
Glycerol, 450. 
Glyceryl, 451. 

caproate, 454. 

caprylate, 454. 

hydrato-oxalate, 339. 

laurate, 454. 

myristate, 454. 

oleate, 451. 

palmitate, 454. 

ricinoleate, 556. 

rutate, 454. 

tristearate, 452. 
Glycocholates, 536. 
Glycocine, 536. 
Glycocoll, 536. 
Glycogen, 467. 
Glycol, 407, 449. 

trichlorethylidene, 477. 
Glycollic acid, 407. 

aldehyde, 407. 
Glycols, 406, 449. 

aromatic, 449. 
Glycyl, 449. 
Glycyrretin, 494. 
Glycyrrhiza, 494. 
Glycyrrhizate of ammonium, 494. 

lime, 494. 
Glycyrrhizic acid, 494. 
Glycyrrhizin, 494. 
Glycyrrhizinum ammoniatum, 494. 
Glyoxal, 407. 
Gnoscopine, 507. 
Goa powder, 337. 
Gold, 242. 

and sodium chloride, 244. 

analytical reactions of, 244. 

coin, 242. 

derivation of word, 34. 

earth, 242. 

fine, 243. 

jewellers', 243. 

leaf, 243. 

mosaic, 242. 

ochre, 53S. 

perchloride, 243. 

sulphide, 243. 

yellow, 538. 
Golden seal, 521. 

syrup. -lt;2. 
Goldthread, 521. 
Gooseberry. 323, 318. 
Gossypiiim, 170. 

impurities in, 698. 

radicis cortex, 120. 
(iothite, 150. 
Goulard's cerate, 209. 

extract. 209. 



740 



Goulard's water, 209. 

Gracillaria, 470. 

Graham's dialytie process, 685. 

law of diffusion, 24. 
Grains, 586. 

of paradise, 414. 
Gramme, 589. 

relation of, to grains, 591, 592. 
Grauati cortex, 359. 
Granatin)), 359. 
Granulated phosphorus, 328. 

citrate of magnesium, 119. 

tin, 239. 

zinc, 20. 
Granulose, 464. 
Grape, 458. 
Grapes, dried, 458. 
Grape-sugar, 458. 
Graphic formula, 136. 
Graphite, 29. 
Grass oil, 414, 416. 
Gravel, 564. 

Gravimetric analysis, 577, 639. 
Gravitation, 585. 
Gravity, 585. 
Gray powder, 200. 
Greengage essence, 404. 
Griffith's mixture, 143. 
Grvuhlia, 524. 
Grindeline, 524. 
Groundnut oil, 456. 
Group tests, 222. 
Guaiaci lignum, 494. 

resinse, 494. 
Guaiacin, 494. 
Guaiacol, 447. 
Guaiaconic acid, 494. 
Guaiacum, resin of, 494. 
Guaiaretic acid, 494. 
Guaiaretin, 494. 
Guaiaretinic acid, 494. 
Guanine, 504. 
Guano, 361. 
Guarana, 528. 
Guilandina honducella, 500. 
Guinea grains, 414. 
Gulancha, 500. 
Gum, 469. 

-acacia, 113. 

-ai'abic, 113. 

British, 467. 

cherry-tree, 469. 

-resins, 419, 423. 

-tragacanth, 112, 464. 
Gummate of calcium, 113, 469. 

lead, 113. 
Gummic acid, 469. 
Gun-cotton, 470. 

-metal, 239. 



Gun-powder, 289. 

Gunj, 494. 

Gurjun balsam, 422. 

Gutta-percha, 417. 

Guttse, 595. 

Gynocardia odorata, 500. 

Gypsum, 104. 

HvEMATEIN, 540. 
Heematin, 531. 
Haematite, brown, 139. 

red, 139. 
Hasmatoxjdin, 540. 
Heematoxylon, 359, 540. 
Half-sovereign, weight of the, 243. 
Haloid salts, 285. 
Hamamelis, 500. 
Hambro blue, 540. 
Hard soap, 453. 
Hardness of water, 314. 
Heat, latent, 85. 

related to chemical action, 607. 

source of, 21. 

specific, 128. 
Hectare, 589. 
Hedeomol, 414. 
Helenin, 414. 
Heliotrope. 497. 
Hellebore, black, 495. 

green, 495. 

white, 525. 

American, 525. 
Helleborein, 495. 
Helleborin, 495. 
Eelleborufi niger, 495. 

viridis, 495. 
Hemialbumose, 536. 
Hemideumi radix, 339. 
Hemidesmic acid, 339. 
Hemlock, 522. 

pitch, 423. 
Hemp, Canadian, 499. 

Indian, 420. 
Hempseed calculi, 573. 
Henbane. 524. 

Henry and Dalton's law, S5. 
Heptane, 396. 
Heptoic aldehyde, 414. 
Herapathite, 512. 
Hesperidene, 413. 
Hevea Brasiliensis, 417. 
Hexabasic acids, 488. 
Hexabromobenzene, 426. 
Hexachlorobenzene, 426. 
Hexylene, 406. 
Hibiscus csculentus, 470. 
High blackberry, 359. 
Hippuric acid, 339, 564, 567. 
Hips, 460. 



741 









Hoffmann's anodyne, 442. 
Hoffner's blue, 540. 
Homatropine, 519. 
Homologous series, 392. 
Homoquinine, 515. 
Honey, 460. 

dew, 462. 
Hop, 423, 526. 

essential oil of, 423. 
Hard cum decortication, 463. 

starch of (fig.), 465. 
Horehound, 500. 
Horsemint, 416. 
Horseradish oil, 412. 
Humulus lupulus, 423. 
Hydrargyri chloridum corrosivum 
impurities in, 698. 
mite, 200. 

impurities in, 
cyanidum, 278. 

impurities in, 
iodidum rubrum, 196. 
impurities in, 
viride, 194. 

impurities in, 698. 
nitrati acidus, liquor, 197. 
nitratis, liquor, 197. 
oxidum fiavum, 201. 
rubrum, 201. 

impurities in, 698. 
perchloridum, 199. 
persnlphas, 197. 
subcJiloridum, 200. 
subsutyhas jlavus, 198. 

impurities in, 698. 
sulphuretum cum sulphure, 205. 
sulphidum rubrum, 205. 
impurities in, 698. 
unguentum, 193. 
Hydrargyrum, 33, 193. 
impurities in, 698. 
ammoniatum, 203. 

impurities in, 694. 
cum creta, 193. 
Hydrastia, 520. 
Hydrastis canadensis, 520. 
Hydrated oxide of iron, 148. 

substances, 84. 
Hydrate of aluminium, 138. 
ammonium, 90. 
cadmium, 247. 
calcium, 106. 
cetyl, 444. 
chromium, 237. 
cobalt, 232. 
glyceryl, 452. 
manganese, 231. 
nickel, 2:; I. 
potassium, 62. 



Hydrate of sodium, 81. 

zinc, 135. 
Hydrates, composition of, 65, 81. 

identified, 379. 
Hydraulic cement, 354. 
Hydrazobenzene, 427. 
Hydric acetate, chloride, nitrate, sul- 
phate, etc. (vide the respective 
acids — Acetic, Hydrochloric, 
etc.). 
Hydride of antimony, 182. 

arsenicum, 170. 

benzoyl, 482. 

copper, 345. 

ethyl, 395. 

methyl, 394. 

phosphorus, 344. 

silicon, 355. 
Hydrides, 121. 
Hydriodic acid, 270. 
Hydrium, 20. 
Hydrobromic acid, 267_, 622. 

volumetric estimation of, 622. 

ether, 400. 
Hydrocarbons, 390. 

acetylene series, 408. 

anthracene series, 429. 

basylous, 391. 

benzene series, 425. 

dihydroxyl derivatives, 449. 

monohydroxyl derivatives, 431. 

naphthalene series, 429. 

neutral, 390. 

normal, 390. 

olefine series, 406. 

paraffin series, 394. 

polyhydroxyl derivatives, 456. 

saturated, 391. 

series of, 392. 

terpene series, 409. 

trihydroxyl derivatives, 450. 

unsaturated, 391. 
Hydrochlorate of morphine, 506. 
Hydrochloric acid, 29, 263. 

analytical reactions of, 266. 

antidote to, 266. 

common, 263. 

dilute. 263. 

in organic mixtures, detection of, 
54 9. 

volumetric estimation o{\ 622. 
Ilvdrocotarnine, 507. 
Hydrocotyle asiatica, 500. 
Hydrocyanic acid. 277. 

analytical reactions of, 281, 549. 

antidotes to. 282. 

dilute. 279. 

from bitter almond ami eherrv- 
laurel. 490. 



742 



Hydrocyanic acid in organic mixtures, 
detection of, 549. 

in the blood,J!S2. 

Schbnbein's test for, 282. 

volumetric estimation of, 624. 
Hydroferricyanic acid, 341. 
Hydroferrocyanic acid, 340. 
Hydrofluoric acid, 342. 
Hydrogen, 20. 

antimoniuretted, 182. 

arseniuretted, 171. 

benzoate, borate, etc. (vide the 
respective acids — Benzoic, Bo- 
racie, etc.). 

combustion of. 21. 

derivation of word, 31. 

explosion of, 22. 

functions of, 122. 

heavy carburetted. 406. 

in artificial light-producers, 22. 

light carburetted, 394. 

lightness of. 23. 

peroxide, 102. 

persulpbide. 301. 

phosphoretted, 343. 

preparation of, 20. 

properties of, 21. 

quantitative estimation of, in or- 
ganic compounds, 669 et seq. 

salts of, 262. 

siliciuretted, 355. 

sulphuretted, 95, 302. 

used for balloons, 23. 

weight compared with air, 24. 
"of 1 litre. 605. 
of 100 cubic inches, 605. 
Hydrogenium, 20. 
Hvdrokinone, 491. 
Hydrolysis, 452. 
Hydrometers, 601. 
Hvdroquinine. 514. 
Hvdrosulphuric acid, 300. 
Hydrosulphyl, 301. 
Hydrous butyl chloral, 479. 

chloral, 477. 

compounds, 84, 121. 
Hydroxyacetic acid, 407. 
Hydroxvbenzoic acid, 483. 

aldehyde. 484. 
Hydroxybenzylic alcohol, 450. 
Hvdroxvformic acid, 4S0. 
Hydroxy 1. 301. 
Hydroxylamine, 504. 
Hydroxv-propane-tricarboxylic acid, 

488. 
Hydroxypropionic acid, 4S0. 
Hydroxysuccinic acid. 4S6. 
Ilydroxytoluic acid, 4S3. 
Hyoscyamia, 524. 



Hyoscyaminte sulpJias, 525. 
impurities in, 69S. 
Hyoscyamine. 524. 
Hyoseyamus, 524. 
Hyoscine, 525. 
Hyper-, meaning of, 146. 
Hypo-, meaning of, 344. 
Hypobromites, 269. 
Hypochloride of sulphur, 304. 
Hypochlorite of calcium, 112. 

sodium, S6. 
Hypochlorites, 291. 
Hypochlorous acid, 291. 
Hypophosphite of calcium, 343. 

iron, 344. 

magnesium. 344. 

potassium, 344. 

sodium, 344. 
Hypophosphites. 344. 

syrup of, 344. 
Hypophosphoric acid, 352. 
Hypophosphorous acid, 343. 
Hyposulphite of calcium, 303. 

sodium, 345. 

standard solution of, 636. 
Hyposulphites, 345. 
Hyposulphurous acid, 345. 

-ic, meaning of, 75, 141. 
Icacin, 4 23. 
Iceland moss, 337. 
Ichthyocolla, 534. 

impurities in, 698. 
-ide. meaning of, 75. 
Iyasuriue, 517. 
Ignatia, 515. 
Ignition, 100. 
Illicium auisatuw, 412. 
Imidogen bases, 427. 
Incense. 424. 
Inch, 595. 
Incineration, 100. 

of filters in quantitative analysis, 
640. 645. 
Indelible ink, 216. 
India-rubber. 417. 

vulcanized, 417. 
Indian barberry, 521. 

cannabis, 420. 

corn-smut, 420. 

gamboge, 423. 

hemp. 420. 

ink, 541. 

ipecacuanha, 524. 

mustard. 445. 

liquorice, 494. 

melissa oil, 416. 

pennywort, 500. 

red, 539. 



743 



Indian yellow, 538. 
Indican, 289. 
Indiglucin, 289. 
Indigo, 289. 

sulphate of, 289. 

-blue, 289. 

-white, 289. 

Indigogen, 2S9. 

Indigotin, 290. 

Indium, 712. 

Infusible white precipitate, 204. 
Infusions, 574. 

Inject io morphine hypodermica, 506. 
Ink, black, 159, 358. 

indelible, 216. 

Indian, 541. 

invisible, 233. 

marking, 216. 

printer's, 541. 

sympathetic, 233. 
Inorganic chemistry, 379. 

compounds, 379. 
Insecticide, 421. 
Introduction, 13. 
Inula helenium, 414, 467. 
Inulic anhydride, 414. 
Inulin, 467. 
Inulol, 414. 
Inverted sugar, 459. 
Iodal, 479. 

Iodate of potassium, 74, 295. 
Iodates, 295. 
Iodic acid, 295. 
Iodide of "ammonium, 271. 

arsenicum, 164. 

cadmium, 247. 

ethyl, 400. 

hydrogen, 271. 

iron, 31, 145, 628. 

lead, 210. 

mercury and potassium, 196. 

potassium, 73, 628. 

silver, 217. 

detection of chloride in, 272. 

starch, 464. 

sulphur, 273. 
Iodides, 270. 

analytical reactions of, 272. 

of mercury, 19-1, 205. 

quantitative estimation of. 65S. 

separation of, from bromides and 
chlorides, 271. 
Iodine, 30, 270. 

chloride, 271. 

derivation of word, 31. 

its analogy to chlorine and bro- 
mine, 270. 

solution of, '272, 637. 

standard solution of, 037. 



Iodine, test of purity, 270. 

tincture of, 638. 

volumetric estimation of, 637. 

-water, 271. 
Iodoform, 399, 439. 
Iodo/ormum, 399, 439. 

impurities in, 698. 
Iodosalicylic acid, 483. 
Iodum, 270. 

impurities in, 698. 
loclinium, 270. 
Ipecacuanha, 524. 
Ipomsea orizabensis, 495. 

purqa, 495. 

simulans, 495, 

turpethum, 198. 
Iridin, 500. 
Iridium, 246. 
Iris florentina, 415. 

versicolor, 500. 
Irish moss, 470. 
Irisin, 500. 
Iron, 139. 

acetate, 148. 

acetonitrate, 155. 

alum, 137. 

ammonio-citrate, 152. 
-tartrate, 153. 

analytical reactions, 158. 

arseniate, 143, 167. 

volumetric estimation of, 633. 

black hydrate, 153. 
oxide, 154. 

bromide, 145. 

carbonate, 142, 634. 

cast, 140. 

chlorides, 145. 

citrates, 152. 

compounds, nomenclature of, 141. 

derivation of word, 32. 

detection of, in presence of alu- 
minium and zinc, 159, 160. 

galvanized. 129. 

hydrated peroxide of, 149. 

hypophosphite, 344. 

in official compounds, estimation 
of, 634, 619. 

iodate, 295. 

iodide, 30. 145, 616. 

lactate, 348. 

magnetic oxide, 15 (. 

estimation of iron in, 633. 

nitrate. 15 1. 

ore, magnetic, L39. 
needle, 150. 
spathic, I 10. 
specular, 139. 

oxide of, 15 1. 

oxyhydrates, 1 IS. 



744 



Iron, oxysulphate, 142. 

perchloride, 145. 

pernitvate, 154. 

peroxide, 150. 

persulphate, 148. 

phosphate, 144, 153, 330. 

volumetric estimation of, 634. 

phosphates and oxalates, separa- 
tion of peroxide of iron from, 
375. 

potassio-citrate, 152. 
-tartrate, 153. 

protected from rust, 140. 

pyrites, 140. 

pyrophosphate, 157. 

quantitative estimation of, 634, 
649. 

and quinine, citrate of, 152, 334. 

red oxide, 150. 

reduced, 156. 

rust, 140. 

saccharated carbonate, 143. 

volumetric estimation of, 634. 

salts, nomenclature of, 141. 

scale, compounds of, 151. 

separation of, from aluminium 
and chromium, 274. 

sodio-citrate, 152. 
-tartrate, 152. 

-stone, clay. 140. 

subcarbonate, 142. 

subsulphate, 1 18. 

sulphate, 142. 

volumetric estimation of, 635. 

sulphide, 144. 

sulphocyanate, 282. 

sulphocyanide, 159, 2S2 

tartrate, 153. 

tersulphate, 148. 

wrought, 140. 
Isatropyl-cocanine, 522. 
Isinglass, 534. 
iso-, meaning of, 471. 
Isoamylic hydride, 396. 
Isobutane, 395. 
Isoheptoic acid, 414. 
Tsomei-ides, 471. 
Isomerism, 471. 
Isomers, physical, 471. 
Isomorphism, the doctrine of, 54. 
Isomorphous bodies, 54, 332. 
Isonandra gntta, 417. 
Ispaghul, 470. 
-ite, meaning of, 75. 
Ivory-black, 541. 

Jaborandt, 526. 
Jaboridine, 527. 
Jaborine, 526. 



Jalap, Mexican male, 495. 

resin, 495. 

Tampico, 495. 

true, 495. 
Jalapa, 495. 
Jalajise resina, 495. 
Jalapic acid, 495. 
Jalapin, 495. 
Jalapinol, 495. 
James's powder, 181. 
Japaconitine, 519. 
Jaune brilliant, 247. 
Jelly, 470, 534. 

vegetable, 470. 
Jequeritin, 494. 
Jequirity, 494. 
Jequirity-zymose, 494= 
Jervia, 525. 
Jervine, 525. 
Juglandine, 525. 
Juylans regia, 525. 

einerea, 525. 
Juices, 574. 
Juniper oil, 414. 
Juniperus, 416. 

sabina, 416. 

Kainit, 61. 
Kairine, 504, 514. 
Kairoline, 514. 
Kaladana resin, 496. 
Kali, 32. 
Kalium, 32. 
Kamala, 421. 
Kaolin, 354. 
Kariyat, 499. 
Kelp, 270. 

Kermes mineral, 180. 
Ketones, 488. 
Kieserit, 116. 
Kilbride mineral, 150. 
Kiln, 106. 

Kilogramme, 589, 590. 
Kilolitre, 597. 
Kilometre, 589. 
Kinate of quinia, 510. 
Kinetic theory, 24. 
King's blue, 540. 
Kino, 358. 
Kinone, 491. 
Kiwach, 239. 
Kokum butter, 454. 
Kola-nut, 528. 
Kooso, 421. 
Kosin, 421. 
Koussin, 421. 
Kousso, 421. 
Krameria, 359. 
Kunch, 494. 



745 



Labarbaque's solution, 86. 
Laboratoiy furniture, xiii. 
Lac-dye, 540. 

-seed, 540 

-shell, 540. 

-stick, 540. 
Lactates, 348. 
Lactic acid, 349, 622. 

volumetric estimation of, 522. 

series of acids, 479. 
Lactoglucose, 462. 
Lactometer, 532. 
Laetophosphate of calcium, 111. 
Lactose, 462. 
Lactuaa, 500. 
Lactucarium, 500. 
Lactucin, 500. 
Ladies' slipper, 500. 
Lgevogyrate, 458. 
LiBvoracemic acid, 319. 
Laevorotation, 458. 
Lasvotartaric acid, 319. 
Laevulose, 458. 
Lakes, 138. 
Lampblack, 541. 
Lamps, gas-, 17, 23. 
Lana 2>hilosophica, 133. 
Lanolin, 452. 
Lanthanum, 712. 
Lanthropine, 507. 
Lapis lazuli, 540. 
Lappa, 500. 
Larch-bark, 359. 
Lard, 45 fr 

benzoated, 457. 

oil, 457. 

prepared, 457. 
Laricis cortex, 359. 
Larix europa, 4.09. 
Larixin, 359. 
Larixinic acid, 359. 
Latent heat, 84. 
Laudanine, 507. 
Laudanosine, 507. 
Laughing-gas, 93. 
Laurate of glyceryl, 454. 
Laurel-camphor, 417. 
Laurie acid, 454. 

aldehyde, 415. 
Lauroccrasi folia, 490. 
Lavandula, 415. 
Lavender oil, 415. 
Laws of chemical combination, 47, 52, 

53. 
Lead, 207. 

acetate, 208. 

analytical reactions of, 210, 547. 
antidotes to, 212. 

carbonate, 208. 
(53 



Lead chloride, 211. 

chromate, 212. 

derivation of word, 32. 

gum mate, 113. 

hydrato-carbonate, 208. 

in organic mixtures, detection of, 
547. 

iodide, 210. 

nitrate, 210. 

oleate, 210. 

oxide, 209. 

oxyacetate, 209. 

oxychromate, 212. 

plaster, 210. 

puce-colored oxide or peroxide 
of, 210. 

pyrophorus, 156. 

quantitative estimation of, 616, 
655. 

red, 210, 539. 

shot, 207. 

subacetate, 209. 

sugar of, 209. 

sulphate, 212. 

sulphide, 212. 
native, 207. 

test for, in water, 211. 

-tree, 213. 

volumetric estimation of solutions 
of acetate of, 616. 

-water, 209. 

white, 208. 
Leadstone, 139. 
Leaf-green, 540. 
Lecanora, 540. 
Lees, 317. 
Legumin, 531. 
Lemon-chrome, 212. 

-juice, 323. 

estimation of mineral acid in, 
663. 

oil, 413. 
Length, unit, of, 5S8. 
Lentisk tree, 421. 
Lepidolite, 225. 
Leptandra vivginica, 500. 
Leptandrin, 500. 
Leucine, 502. 
Leucomaines, 502. 
Levant wormseed, 497. 
Levisticum, 424. 
Lichen blue, 540. 

sugar, 466. 
Lichenin, 467. 

Light carbonate of magnesium, 117. 
carburetted hydrogen, 394. 
magnesia, 1 L9. 
Lignin, 470. 
Lime, caustic, 105. 



746 



Lime, bisulphite, 305. 

chloride of, 112. 

-kiln, 106. 

quick-, 105. 

slaked, 106. 

superphosphate of, 327. 

volumetric estimations, 616. 

-water, 106. 
Lime-juice, 323. 

estimation of mineral acid in, 
663. 

oil, 413. 
Limestone, 104. 

magnesium, 116. 

mountain, 116. 
Limonenes, 409. 
Limonis cortex, 413. 

succus, 324. 

impurities in, 698. 
Limonite, 150. 
Line, 595. 

Liniment of mercury, 193. 
Liniments, 574.. 
Linimentum ammonise, 453. 

calcis, 453. 
Linoxyn, 455. 
Linolein, 455. 
Linseed, 455. 

cake, 455. 

oil, 455. 

tea, 470. 
Linum, 455, 470. 

usitatissimum, 470. 

impurities in, 698. 
Liqueurs, 436. 
Liquidambar orientate, 485. 
Liquid camphor, 417. 

definition of, 58. 
Liquids, specific gravity of, 599. 

official, specific gravity of, 600. 
Liquorice, 462. 

sugar, 462, 494. 
List of apparatus, xii. 

chemicals, xiv. 

reagents, xiii. 
Litharge, 208. 
Lithates, 361. 
Lithic acid, 361. 
Lithii benzoa8, 225. 

impurities in, 700. 

bromidum, 225. 

impurities in, 700. 

carbonas, 225. 

impurities in, 700. 

citras, 224. 

impurities in, 700. 

salicylas, 225. 

impurities in, 700. 
Lithium, 224. 



Lithium, analytical reaction of, 225. 

benzoate, 225. 

bromide, 225. 

carbonate, 225. 

citrate, 224. 

derivation of word, 33. 

flame, 226. 

fluoride, 225. 

salicylate, 225. 

silicate, 225. 

sulphate, 225. 

urate, 225. 
Litmus, 94, 540. 

-paper, 94, 95. 

solution of, 95. 
Litre, relation of, to pints, 589. 
Liver of sulphur, 67. 
Lixiviation, 87. 
Loadstone or lodestone, 139. 
Loaf-sugar, 460. 
Lobelia, 525. 

vinegar, 297. 
Lobelina, 525. 
Lobeline, 525. 
Logwood, 29, 540. 

solution of, bleached by chlorine, 
29. 
Loganetin, 496. 
Loganin, 496. 
Long pepper, 527. 
Looking-glasses, 239. 
Lotio liydrargyri nigra, 202. 
Louisa-blue, 540. 
Lozenges, 574. 
Lucifers, 24. 
Lugol's solution, 272. 
Lunar caustic, 215. 
Lupulin, 423. 

oleo-resin of, 423. 
Lupuline, 526. 
Lupulinic acid, 423. 
Lupulinum, 423. 

impurities in, 700. 
Lupidus, 423, 526. 
Luteolin, 538. 
Lutidine, 503. 
Luting, 97. 

fireclay, 199. 

linseed-meal, 97. 
Lyco'podium, 455. 

impurities in, 700. 

Mace, 454. 

fixed oil of, 454. 

volatile oil of, 415. 
Macis, 415. 
Madder, 429, 539. 
Magenta, 541. 
Magnesia, 119. 



747 



Magnesia, effervescing citrate, 119. 
impurities in, 700. 

calcined. 119. 

fluid, 118. 

hydrous carbonate, 117. 

levis, 117. 

ponder -osa, 119. 
Magnesian limestone, 116. 
Magnesii carbonas, 117. 

impurities in, 700. 
levis, 117. 

carbonatis, liquor, 118. 

citrus granulatus, 119. 
impurities in, 700. 

sutyhas, 116. 

impurities in, 700. 

sulphis, 305. 

impurities in, 700. 
Magnesite, 116. 
Magnesium, 116. 

analytical reactions of, 120. 

and ammonium arseniate, 120. 
ammonium phosphate, 120. 

carbonate, 120. 

chloride, 116. 

citrate, 119. 

derivation of word, 32. 

detection of, in presence of ba- 
rium and calcium, 123. 

euxanthate, 538. 

for analytical purposes, 171. 

limestone, 116. 

oxide, 119. 

phosphate in bones, 110. 

purrate, 538. 

quantitative estimation cf, 647. 

separation from barium and cal- 
cium, 120, 123. 

silicate, 354. 

sulphate, 116, 647. 

sulphite, 305. 
Magnetic iron ore, 139. 

oxide of iron, 154. 
Magnolia, 500. 

Magpie test for mercury, 206. 
Maize-smut, 420. 

-starch (fig.), 465. 
Malachite, 188. 
Malaguti's law, 379. 
Malatc of atropine, 519. 

nicotine, 526. 
Malatcs, 348. 
Male fern oil, 456. 
Malic acid, 348. 

series of acids, 486. 
Mallotoxin, 421. 
Mallow tea, 470. 
Malonic acid, 4S7. 
Malt, 468. 



Malt, extract of, 469. 

substitute, 460. 
Maltose, 459, 462, 681. 
Manganate of potassium, 76, 229. 
Manganese, 228. 

analytical reactions of, 230. 

black oxide of, 230. 

Crum's test for, 231. 

derivation of the word, 33. 

quantitative analysis of black ox- 
ide of, 648. 

sulphate, 231. 

impurities in, 700. 
Mangani oxidum nigrum, 228. 

sulphas, 231. 
Manganous chloride, 228. 

hydrate, 231. 

sulphide, 230. 
Mangosteen oil, 454. 
Manihot starch (fig.), 465. 
Manna, 457. 

impurities in, 700. 
Mannite, 456, 457. 
Manufacturing chemjsts, 14. 
Manures, anatysis of, 686. 
Maranta starch (fig.), 465. 
Maraschino, 436. 
Marble, 104. 
Margarine, 454. 
Margosa-bark, 500. 
Mangold, 500. 
Marine soap, 454. 
Mariotte's law, 53. 
Marjoram, 415. 
Marking-ink, 216. 
Marl, 136. 
Marrubein, 500. 
Marrubium, 500. 
Marseilles soap, 453. 
Marsh -gas, 394. 
Marshmallow, 470. 
Marsh's test for arsenicum, 170. 
Massa ferri carbonatis, 143. 

copaiba', 422. 

hi/drargi/ri, 193. 
Massicot, 208. 
Mastic, 421. 
Mastiohe, 421. 
Mastichic acid, 421. 
Masticin, 421. 
Mate, 528. 
MatictB folia, 500. 
Matico, 500. 

Matricaria ehainomilla, 412. 
Mauve, 491. 
May-apple, 421. 
Meadow-sweet, oil of. 484, 197. 
Measurement ol' temperature, 579. 
Measures, 586 et aeq. 



<A 



INDEX. 



Mechanical and chemical combination, 
difference between, 30, 36. 

medicines, 239. 
Meconate of morphine, 506. 
Meconic acid, 349, 552. 
Meconidine, 507. 
Meconine, 507. 
Meconoisine, 507. 
Meerschaum, 354. 
Mel, 460. 

impurities in, 700. 

despumatum, 460. 
Melam, 356. 
Melasses, 462. 
Melegueta pepper, 414. 
Melia azedarach, 500. 
Melissa, 416. 

Melissyl, palmitate of, 444. 
Melitose, 461. 
Mellitic, 4SS. 
Melon essence, 404. 
.Melting-points, Table of, 583. 

of fats, etc., to determine, 583. 

of metals, 584. 
Memoranda, analytical, 257, 364. 
Menispermum canadense, 520. 
Mentha, 415. 
Menthse. piperita, 415. 

viridis, 415. 
Menthene, 415. 
Menthol, 415. 
Mercaptans, 439. 
Mercuric ammonium, chloride of, 203. 

chloride, 199, 203. 

cyanide, 278. 

hexiodide, 271. 

iodide, 194, 204. 

nitrate, 197. 

oxide, 201. 

oxynitrates, 197. 

oxysulphate, 198. 

phenylate, 447. 

salts, 193. 

analytical reactions of, 205. 

sulphate, 197. 

sulphide, 204. 
Mercurius vitse, 178. 
Mercurous ammonium, chloride of, 
204. 

chloride, 200, 202. 

chromate, 206. 

iodide, 194. 

nitrate, 196. 

oxide, 202. 

salts, 193. 

analytical reactions of, 204. 

sulphate, 198. 

sulphide, 205. 
Mercury, 192. 



Mercury, amido-chloride, 203. 

ammoniated, 203. 

arnmomo-chloride, 203. 

analytical reactions of, 202. 

antidotes to, 206. 

basic sulphate, 198. 

black oxide, 202. 

carbonates, 206. 

chlorides, 198. 

cyanide, 278. 

derivation of word, 33. 

fulminate, 216. 

galvanic test for, 205. 

hexiodide, 271. 

iodides, 194, 203. 

magpie test for, 206. 

native sulphide, 192. 

nitrates, 197. 

nomenclature of salts of, 193. 

of life, 178. 

in organic mixtures, detection of, 
547. 

oxides, 201. 

oxynitrates, 197. 

oxysulphate, 198. 

oxysulphide, 205. 

quantitative estimation of, 653. 

subchloride, 200. 

sulphates, 197. 

sulphide, 192, 205. 

yellow oxide, 201. 
Mesitylene, 425. 
Mesoxalic acid, 487. 
meta-, meaning of, etc., 240, 472. 
Metaboric acid, 332. 
Metaehloral, 477. 
Metacinnamein, -185. 
Metadihydroxylbenzol, 448. 
Metaldehyde, 475. 
Metallic elements, 15. 
Metalloids, 15. 
Metals, 15. 

of minor pharmaceutical import- 
ance, 224. 

quantitative estimation of, 639. 

Table of the fusibility of, 584. 
Metamerides, 472. 
Metamerism, 472. 
Metantimonic acid, 179. 
Metaphosphates, 349. 
Metaphosphoric acid, 349. 
Metastannates, 241. 
Metastannic acid, 240. 
Metastyrol, 485. 
Metathesis, 77, 291. 
Metavanadates, 332. 
Methacrylic acid, 4S0. 
Methane, 394. 

substitution-products of, 401. 



749 



Methoxycatechol, 333. 
Methylal, 476. 
Methylamine, 502. 
Methylated spirit, 432. 

sweet spirit of nitre, 433. 
Methylic alcohol, 432. 

detected in presence of ethylic 
alcohol, 432. 
Methyl-benzene, 427. 

chloride of, 401. 

coniine, 523. 

carbinol, 434. 

dichlorobenzene, 428. 

ethyl, 395. 

group, 428. 

hydride of, 394. 

monochlorobenzene, 428. 

morphine, 509. 

-orange, 623. 

-phenb'ene, 425, 427. 

-propylphenoene, 425. 

-protocatechuic aldehyde, 363. 

-theobromine, 529. 

salicylate of, 404, 482. 

trichlorobenzene, 428. 
Metre, 588. 

relation of, to inches, 588, 590. 
Metric system, 587 et seq. 

of weights and measures, its 
relation to the English or 
United States, 588 et seq. 
weights and measures of, 587 
et seq. 
Me am, 424: 
Mezereon, 421, 492. 
Mezereum, 421. 
Mica, 136. 

pants, 461. 
Microcosmic salt, 373. 
Microscopic examinations of urinary 

sediments, 565. 
Microscopy of starches, 466. 
Microspectroscope, 545. 
Mindererus, spirit of, 91. 
Milk, 531. 

-curdling ferment, 532. 

-poison, 502, 556. 

-sugar, 462. 

-sulphur, 300. 
Miinotannic acid, 359. 
Mineral acids, detection of, in organic 
mixtures, 5 19. 

chameleon, 230. 

kermes, ISO. 

Kilbride, 150. 

purple, 539. 

rouge, 540. 
Minerals, general analysis of, 370 et 
seq. 

63* 



Minerals, special analysis of, 371. 

Minim, 595. 

Minium, 208. 

Mint, 415. 

Mistura ferri composita, 143. 

potassii citratis, 324. 
Mixture, definition of, 57. 

diiferent from chemical combina- 
tion, 30. 
Mixtures, 574. 
Mohr's burette, 612. 
Moist sugar, 460. 
Molasses, 462. 
Molecular volume, 55. 

weight, 55, 262, 606. 

weights, definition of, 58. 
Molecule, definition of, 57. 
Molecules, 42, 58. 
Molybdate of ammonium, 331. 

sodium, 331. 
Molybdenum, 712. 

sulphide, 331. 
Molybdic acid, 555. 
Monads, 122. 
Monamines, 502. 
Monarda, 416. 

Monhydroxyl derivatives of the par- 
affins, 431. 
Moniodoethane, 400. 
Monobasic acids, 261. 
Monobasylous radicals, 261. 
Monobrom-camphor, 417. 
Monobromethane, 400. 
Monobromobenzene, 426. 
Monochlorobenzene, 426. 
Monochloromethane, 397. 
Monochloromethylbenzene, 428. 
Monoformin, 445. 
Mononitrocellulin, 470. 
Monsel's solution, 148. 
Morbid urine, 557. 
Mordants, 138. 
Mori sticcus, 539. 
Morphina, 506. 

impurities in, 700. 
Morphinsc acctas, 506. 

hydrochloras, 506. 

sulphas, 506. 
Morphine or morphia, 506. 

acetate, 506. 

analytical reactions of, 507. 

hydrochloric, 506. 

in organic mixtures, detection of, 
550. 

quantitative estimation of, 679. 
Morrhuine, 455. 
Mosaic gold. 242. 
Mosclnis, 534. 

moschtferiWt 53 1 



750 



Mother-liquor, 107. 
Motion from heat, 85. 
Mottled soap, 453. 
Mountain blue, 540. 

-limestone, 116. 
Mucic acid, 462. 
Mucilage of bael, 470. 

gum-acacia, 113. 

linseed, 470. 

mar shin allow, 470. 

quince, 470. 

slippery elm, 470. 

starch, 464. 

squill, 470. 

tragacanth, 114. 
Mucilago acacise, 113. 

amy!>, 464. 

tragaeanthse, 114. 
Mucunu pntriens, 239. 
Mulberry calculus, 573. 

-essence, 404. 

-juice, 539. 

-sugar, 458. 
Mulder's process for estimating alco- 
hol, 684. 
Multiple proportions, law of, 48, 195, 

289. 
Murexid, 361. 
Muscarine, 502. 
Musk, 534. 

deer, 534. 
Mustard, 445. 

artificial oil of, 445. 

essential oil of, 445. 

fixed oil of, 456. 

"poultice," 445. 
Mylatris cichorii, 418. 
Myrcia acris, 436. 
Myristate of glyceryl, 454. 
Myristic acid, 454. 
Myristica, 415. 
Myristicene, 415. 
Myristicol, 415. 
Myristin, 454. 

Myronate of potassium, 445. 
Myrosin, 445. 
Myrrh, 424. 
Myrrh a, 424. 
Myrrhic acid, 424. 
Myrtus communis, 415. 
Mystery gold, 243. 
Mytiloxine, 502. 

Naphthalene, series of hydrocar- 
bons, 429, 504. 
Naphthalic acid, 429. 
Narceine, 507. 
Narcotine, 507. 
Natal aloes, 430. 



Nataloin, 430. 
Natrium, 32. 
Natural philosophy, 43. 
Nectandra Eodisei, 520. 
Nectandrae cortex, 520. 
Nectandrine, 520. 
Needle iron ore, 150. 
Neroli oil, 413. 
Nessler test, 615. 
Neuridine, 502. 
Neurine, 502. 
Neutral chromate, 103. 
Neutralization, 94. 
Nickel, 233. 

analytical reactions of, 234. 

arsenio- sulphide, 233. 

cobalticyanide, 234. 

cyanide, 234. 

derivation of word, 34. 

hydrate, 234. 

separation of, from cobalt, 234. 

sulphide. 234. 
Nickar nuts, 500. 
Nicotia, nicotine, nicotina, or nicoty- 

lia, 526. 
Nicotimxa tabacum, 526. 
Nieschnic bitters, 521. 
Nihilum album, 133. 
Nim, 500. 
Niobium, 713. 
Nitrate of ammonium, 93. 

ar^ent-ammon-ammonium, 204. 

barium, 102. 

bismuth, 248. 

cadmium, 247. 

iron, 154. 

lead, 210. 

mercury, 196. 

potassium, 61, 286. 

silver, 215. 

standard solution of, 624. 

sodium, SI, 284. 

strontium, 226. 
Nitrates, 2S3. 

analytical reactions of, 2S7. 

quantitative estimation of, 659. 
Nitre, 284. 

cubic, 284. 
• sweet spirit of, 351, 402, 433. 
Nitric acid, 286. 

antidotes to, 290. 
in organic mixtures, detec- 
tion of, 549. 
volumetric estimation of, 622. 

anhydride, 288. 

oxiile, preparation of, 2S7, 

peroxide, 2S7. 
Nitrification, 284. 
Nitrile bases. 427. 



751 



Nitriles, 486. 
Nitrite of amy], 351. 

ethyl, 351. 

potassium, 350. 

and cobalt, 351. 
Nitrites, 350. 

analytical reactions of, 350. 
Nitrobenzene, 426. 
Nitrobenzol, 426. 

in oil of bitter almonds, test for, 
490. 
Nitrocellulins, 470. 
Nitro-ethane, 403. 
Nitrogen, 25. 

derivation of word, 31. 

in the atmosphere, 26. 

oxides, 288. 

peroxide, 288. 

preparation of, 25, 235, 351. 

properties of, 26. 

quantitative estimation of, in' or- 
ganic compounds, 672 et seq. 

relative weight of, 26. 
Nitrohydrochloric acid, 184, 287. 
Nitropentane, 405. 
Nitrous acid, 287. 

anhydride, 287. 

ether, 351. 

oxide, 288. 
Nonane, 396. 
• Non-drying oils, 455. 
Non -metallic elements, 15. 
Non-metals, 15. 

Nordhausen sulphuric acid, 309. 
Normal hydrocarbons, 390. 
Notation, 41 et seq. 
Notes, analytical, 257, 364. 
Nutmeg, expressed oil, 454. 

oil of, 415. 
Nutrition, plastic elements of, 533. 
Nux vomica, 515. 

Oak-bark, 357. 
Oatmeal, 463. 
Occlusion, 246. 
Ochre, 538. 
Octohedron, 169. 
(Enanthylic acid, 481. 
Official liquids, specific gravity of, 
600. 

substances, volumetric estimation 
of, 611, 613, 620, 62:5, 629, (>;'>2. 

formula, 28. 
Officinal formula, 28. 
Oils and fats, composition of, 451. 
Oils, analysis of, 686. 

drying, 155. 

essential, 110. 

teste! for alcohol, 111. 



Oils, fixed, 455. 

non-drying, 455. 

volatile, 410. 

process for, 411. 
Ointments, 574. 
Okra, 470. 

-ol, the termination, 450. 
Olea destillata, impurities in, 701. 
Oleate of glyceryl, 451. 

of lead, 210. 
Oleates, 452. 
Oleatum hydrargyri, 452. 

veratrinse, 452. 
Olefiant gas, 406. 

Olefine series of hydrocarbons, 406. 
Olefines, relation to paraffins and ace- 
tylenes, 407. 
Oleic acid, 452. 
Oleine, 451. 
Oleo-resins, 419. 
Oleoresina asjndii, 456. 

capsici, 423. 

cubebse, 422. 

lupulini, 423. 

piperis, 423. 

zingiberis, 423. 
Oleum adijris, 454. 

sethereum, impurities in, 701. 

amygdalse amarse, 455. 
didcis, 455. 
expressum, 455. 

andropogi ciirati, 417. 
impurities in, 701. 

anethi, 412. 

anisi, 412. 

anthemidis, 412. 

arachis, 456. 

aurantii corticis, 412. 
Jlonim, 413. 

bergamii, 413. 

cajuputi, 413. 

carui, 413. 

caryophylli, 413. 

chenopodi 7, 417. 

cinnamon, i, 414. 

copaibse, 414. 

eoriandri, 414. 

crotonis, 455. 

cubebse, 414. 

erigerontis, 414. 

eucalypti, 111. 

funiculi, III. 

gaultheriee, 104. 

impurities in, 701. 

gossypii seminis, 1 15. 

hedeomte, 111. 

>„,>,•/. III. 

lavandnlse, 415. 
flomm, 415. 



752 



Oleum lavandulse florum, impurities 
in, 701. 

limonis, 413. 

lini, Abb. 

maris, 414, 454. 

menthse piperita, 415. 
viridis, 415. 

morrhuse, 455. 

myrrise, 4l5. 

myristicse, 415. 

expressum, 454. 

olivss, 456. 

impurities in, 701. 

phosphoratum, 327. 

pic«'« liquids, 423. 

pimentse, 413. 

pndegii, 415. 

ririni, 456. 

rosa?, 415. 

rosmarini, 415. 

rHfce, 415. 

8abinse, 416. 

santali, 416. 

sassafras, 416. 

sesami, 457. 

sinapis volatile, 445. 

impurities in, 701. 

terebinth inse, 409. 

theobromse, 454. 

impurities in, 701. 

thy mi, 41 6. 

tiyJtt, 455. 

Valerianae, 416. 
Olibanum, 424. 
Olive-oil, 451, 456. 
Omentum, 454. 
Omum oil, 412. 
Opal, 354. 

Ophelia chirata, 351. 
Ophelic acid, 351. 
Opianic acid, 507. 
Opianine, 507. 
0/> it pulvis, 506. 
Opium, 506. 

detection of, in organic mixtures, 
552. 

denarcotisatum, 506. 

estimation of morphine in, 679. 

impurities in, 701. 

vinegar, 297. 
Orange-chrome, 212. 

-flower, 413. 
oil, 413. 

-rind oil, 412. 
Orchil, 540. 
Orchis tuber, 470. 
Orcin, 449, 540. 
Ordeal-poison, 526. 
Orellin, 539. 



Organic analysis, 669. 

chemistry, 383. 

advice to students on, 381. 

compounds, 383. 

composition of, 384. 
notation of, 388. 

radicals, 391. 
Origan tint, 415. 
Orpiment, 538. 
Orris, butter of, 415. 

oil of, 415. 
ortho-, meaning of, 350. 
Orthodihydroxylbenzol, 449. 
Orthophenolsulphonic acid, 439. 
Orthophosphates, 350. 
Orthophosphoric acid, 350. 
Orthovanadates, 332. 
Oryza, starch of (fig.), 465. 

sativa, 464. 
Os ustum, 109. 
Osmium, 246, 713. 
Otto of rose, 415. 
Ounce, 586. 
Ourari, 517. 

-ous, meaning of, 75, 141. 
Ovum, 530. 
Oxalate of ammonium, 94. 

barium, 316. 

calcium, 315. 

cerium, 227. 

iron, 315. 

potassium, 316. 

silver, 316. 

sodium, 315. 

strontium, 227. 
Oxalates, 315. 

analytical reactions of, 316, 549. 

from phosphates and ferric oxide, 
separation of, 375. 

quantitative estimation of, 665. 
Oxalic acid, 315. 

antidotes, 316. 

in organic mixtures, detec- 
tion of, 549. 
purified, 316. 
standard solution of, 613. 
Ox-bile, 536. 

-gall, 536. 
Oxides identified, 376. 
Oxides of nitrogen, 288. 
Oxidizing flame, 373. 
Oxyacanthine, 520. 
Oxyacetate of copper, 190. 

of lead, 209. 
Oxyacid salts, 285. 
Oxyacids of sulphur, 346. 
Oxycarbonate of bismuth, 250. 
Oxychloride of antimony, 178. 
Oxychromate of lead, 212. 



753 



Oxygen, 16. 

derivation of word, 31. 

from ozone, 273. 

in the air, 16, 26. 

its relation to animal and veg 
etable life, 19. 

preparation of, 16, 112. 

properties of, 19. 

quantitative estimation of, in or- 
ganic compounds, 640 et seq. 

solubility in water, 19. 

specific gravity of, 24. 

weight of 100 cubic inches, 607. 
Oxygenated water, 102. 
Oxyhydrates of iron, 148. 
Oxyiodate of iron, 295. 
Oxymalonic acid, 482. 
Oxymel, 461. 

of squill, 461. 
Oxynitrates of mercury, 197. 

bismuth, 249, 250. 
Oxysalts, 285. 
Oxysuccinic acid, 482. 
Oxysulphate of iron, 142. 

mercury, 198. 
Oxysulphide of antimony, 179. 

mercury, 205. 
Ozokerite, 444. 
Ozone, 372, 569. 

Palas tree, 358. 
Palladium, 246. 
Palm oil, 454. 
Palmitate of cetyl, 444. 

glyceryl, 454. 

melissyl, 444. 
Palmitic acid, 494. 
Palmitine, 454. 
Pancreatin, 536. 
Papaine, 536. 
Pupavev rhceas, 539. 

somniferum, 505. 
Papaverine, 507. 
Papnveris, capsule, 505. 
Paper, bibulous, 107. 

for filtering, 107, 639. 
Papers, test-, 94. 
para-, meaning of, 319. 
Paracyanogen, 280. 
Paraffin, 396. 

oil, 396. 

scries of hydrocarbons, 394. 

wax, 396. 
Paraffinic acid, 397. 
Paraffins, gaseous, 394. 

hard. 396. 

monhydroxyl derivatives of, 131. 

relations to defines and acety- 
lenes, 107, 



Paraffins, soft, 396. 

solid, 396. 
Paraffinum durum, 396. 
liquidum, 396. 
molle, 396. 
Paraguay tea, 528. 
Parahydroxybenzoic aldehyde, 484. 
Paraldehyde, 475. 
Parallin, 498. 
Parapeptone, 536. 
Paratartaric acid, 319. 
Pareira, 521. 
Paricine, 521. 
Parietinic acid, 337. 
Parigenin, 498. 
Parilla, 520. 
Paris blue, 540. 

red, 539. 
Particles, elementary, 46. 
Patent sugar, 460. 
Paullinia sorbilis, 528. 
Pavy's solution, 682. 
Pearlash, 61. 
Pearl barley, 463. 

-sago starch (fig.), 465. 
-white, 250, 541. 
Peas, 533. 
Pectin, 470. 
Pelargonic acid, 481. 
Pelletierine, 359. 
Pellitory-root, 421. 
Pelosine, 520. 

Pentachloride of antimony, 178. 
Pentane, 395. 
Pentathionic acid, 316. 
Pentylic acid, 479. 

alcohol, 443. 
Pepo, 500. 
Pepper, black, 526. 
cayenne, 522. 
cubeb, 526. 
long, 526. 
oil of, 522. 
white, 526. 
Peppermint oil, 415. 
Pepsin, 535. 

Pepsinum saccharatum, 536. 
impurities in, 701. 
Peptone, 535. 
per-, meaning of. 146. 
Perbromates, 269. 
Percha tree, 117. 
Perchlorate of potassium, 293. 
Perchloric acid, 293. 
Perchloride of gold, 243. 
iron, 1 IT.. 
platinum, 245. 



nes, 412. 



754 



Periodic law, the, 380. 
Periodide of ammonium, 271. 

potassium, 271. 
Permanganate of potassium, 76, 229. 
its use in volumetric analysis, 
629. 
Pernitrate of iron, 154. 
Peroxide of barium, 102. 

hydrogen, 102. 

iron, 150. 

lead, 210. 

nitrogen, 2S7. 
Persian berries, 538. 
Personne's solution, 628. 
Persulphate of iron, 148. 
Persulphide of hydrogen, 301. 
Peru, balsam of, 419, 485. 
Peruvine, 485. 
Petalite, 225. 
Petroleine, 396. 
Petroleum benzin, 396. 

ether, 396. 

spirit, 396. 

testing, 410. 
Pettenkofer's test for presence of bile, 

537. 
Peumus boldus, 413. 
Pewter, 177, 208, 239. 
PhEeoretine, 337. 
Pharaoh's serpents, 356. 
Pharbitisin, 496. 
Pharbitis nil, 496. 
Pharmaceutical chemists, 14. 

Society of Great Britain, exam- 
inations of, 14. 
Pharmacists, 14. 
Pharmacy, 14. 
Phenic acid, 446. 

alcohol, 446. 
Phenb'ene, 426. 
Phenol, 446. 

constitution of, 448. 

mercury, 447. 

salicylic, 483. 
Phenols, 446. 
Phenolthalein, 623. 
Phenylamine, 504. 
Phenylates, 447. 
Phenylcarbinol, 449. 
Phosphate of ammonium, 93. 

barium, 331. 

calcium, 104, 110, 331. 

iron, 144, 331. 

magnesium and ammonium, 120. 
and ammonium from oxa- 
lates and ferric oxide, sep- 
aration of, 375. 
in bones, 110. 

silver, 217. 



Phosphate of sodium, 111. 

how prepared from phosphate 
of calcium, 111. 
327. 

analytical reactions of, 330. 

quantitative estimation of, 665. 
Phosphide of zinc, 328. 
Phosphites, 351. 

test for, 342. 
Phosphorated oil, 327. 
Phosphoretted hydrogen, 343. 
Phosphoric acid, 25, 328, 348. 
diluted, 329. 

quantitative estimation of free, 
666. 

anhydride, 25, 351. 
Phosphorous acid, 351. 
Phosphorus, 24, 327. 

combustion of, 24. 

derivation of word, 31. 

detection of, in organic mixtures, 
550. 

granulated, 327. 

impurities in, 701. 

pills, 327. 

properties of, 24. 

red or amorphous, 328. 

trihydride, 343. 
Phthalic acid, 337. 

anhydride, 486. 

series of acids, 486. 
Phyllocyanin, 540. 
Phylloxanthin, 540. 
Phvsical isomerides, 471. 
Physics, 43. 
Phynostigma, 526. 
Phy^ostigmine, 526. 

salicylate, 526. 

impurities in, 701. 
Phytolacca, 500. 
Phytolaccin, 500. 
Picoline, 503. 
Picric acid, 448, 538. 
Picrotin, 496. 
Picrotoxinum, 496. 

impurities in, 701. 
Pigments, 538. 
Pigmentum nigrum, 541. 
Pills, 574. 
Pilocarpidine, 526. 
Pilocarpine hydrochloras, 526. 

impurities in, 701. 
Pilocarpine, 526. 
Pilocarpus, 526. 
Pilule aloes et ferri, 142. 

antimonii composite, 200. 

catliarticx composite, 201. 

ferri composite, 143. 
iodidi. 31. 



755 



Pilulse phosphori, 327. 

plumbi cum opio, 209. 
Pimaric acid, 419. 
Pimenta, 413. 
Pimento, 413. 

oil, 413. 
Pimpinella anisum, 412. 
Pineapple, essence of, 404. 
Pinic acid, 419. 
Pinipicrin, 416. 
Pink-root, 528. 
Pink saucers, 539. 

the common, 497. 
Pins, 239. 
Pint, 599. 
Pinus, 409, 419. 
Piper nigrum, 527. 
Piperia, 527. 
Piperic acid, 527. 
Piperidia, 527. 
Piperidine, 527. 
Piperina, 527. 

impurities in, 701. 
Piperine, 527. 
Pistachio, terebinth us, 409. 
Pitch, 423. 

Burgundy, 421. 
Pituri, 526. 
Pix burgundica, 421. 

canadensis, 423. 

liquida, 423. 
Plantago ispaghula, 470. 
Plants ancC animals, complementary- 
action on air, 19. 
Plaster of ammoniacum and mercury, 
193. 

of Paris, 104. 
Plasters, 210, 574. 
Plastic elements of nutrition, 533. 
Platinic salts, 245.. 
Platinous salts, 245. 
Platinum, 244. 

analytical reactions of, 245. 

and ammonium chloride, 98, 644. 

and potassium chloride, 77. 

black, 245. 

derivation of word, 34. 

-foil, 76, 244. 

perchloride, 245. 

residues, to recover, 246. 

spongy, 246. 

sulphide, 245. 
Pleurisy-root, 499. 
Plumbago, 30. 
Plumbi acetas, 209. 

impurities in, 701. 

carbonas, 208. 

impurities in, 701, 702. 

emplastrum, 211. 



Plumbi iodidum, 210. 

impurities in, 702. 
nitras, 210. 

impurities in, 702. 
oxidum, 208. 

impurities in, 702. 
subacetatis, liquor, 209. 
Plumbic peroxide, 210. 

acetate, sulphate, etc. (vide Salts 
of Lead). 
Plumbum, 33. 
" Plummer's pills," 200. 
Pocula emetica, 177. 
Podophyllum, 421. 
Poison ivy, 360. 

oak, 360. 
Poisonous alkaloids, 502. 
Poisons, antidotes to (vide Antidote's, 
detection of, in organic mix- 
tures, 545 et seq.) 
of cheese, fish, milk, etc., 502, 
557. 
Polybasic acids, 262. 
Polybasylous radicals, 262. 
Polychroite, 538. 
Poli/gala senega, 498. 
Polygalic acid, 498. 
Polymerism, 472. 
Polymorphism, 471. 
Polymorphous bodies, 473. 
Polysulphide of calcium, 302. 
Pomegranate-rind, 359. 

-root bark, 359. 
Porcelain, 351. 
Porter, 436. 
Portland cement, 354. 
Port wine, 436. 
Potash alum, 136. 

solution of caustic, 67. 

to prepare pure, 67. 
sulphurated, 67. 
volumetric estimation of solution 

of, 617. 
-water, 67. 
Potashes, 62. 
Potassa, 67. 

impurities in, 702. 
cum calce, 67. 

impurities in, 702. 
sidphurata, 67. 

impurities in, 702. 
Potassce (vide Potaesii). 
effervesccn8, liquor, 71. 
liquor, 62, 67. 

to prepare pure, 67. 
Potassic hydrate, etc. {vide Salts of 

Potassium). 
Potassii acetas, 69. 

impurities in, 702. 



756 



Potassii acetas, volumetric estimation 
of, 619. 
bicarbonas, 70. 

impurities in, 702. 
bichromas, 235. 

impurities in, 702. 
bitartras, 61, 79, 318. 

impurities in, 702. 
bromidum, 75, 626. 

impurities in, 702, 703. 
carbonas, 61. 
pur us, 61. 

impurities in, 703. 
chloras, 292. 

impurities in, 703. 
citras, 72. 

impurities in, 703. 
cyanidum, 278. 

impurities in. 703. 
et sodii tartras, 73, 86. 

impurities in, 703. 
ferrocyanidum, 278. 

impurities in, 703. 
hyjiophosphis, 341. 

impurities in, 703. 
iodidum, 74. 

impurities in, 703. 
nitras, 72, 661. 

impurities in, 703. 
permangcuias, 76, 229. 

impurities in, 703. 

volumetric estimation of, 619. 
sulphas, 72, 2S6. 

impurities in, 703. 
sushis, 305. 

impurities in, 703. 

volumetric estimation of, 631. 
tartras, 73. 

impurities in, 704. 
Potassio-citrate of iron, 151. 
-cupric tartrate, 6S1. 
-tartrate of antimony, 179, 318. 

of iron, 152. 
Potassium, 61. 
acetate, 68. 
acid carbonate (vide Carbonate). 

tartrate, 79. 
analytical reactions of, 77. 
bicarbonate, 70, 617. 

chemically pure, 61S. 
bichromate, 235. 
bitartrate, 79, 31 S. 
boro-tartrate, 333. 
bromate, 76. 
bromide, 75. 
carbonate, 61, 617. 

chemically pure, 61S. 
carbonates, volumetric analysis 
of, 617. 



Potassium chlorate, 16, 292. 

chloride, 77. 

chromate, 103. 

and platinum chloride, 77. 

citrate, 72. 

cobalticyanide, 233. 

cyanate, 338. 

cyanide, 278. 

derivation of word, 32. 

ferrate, 141. 

ferricvanide, 341. 

ferrocyanide, 27S, 342. 

flame test, 79. 

hydrate, 62. 

to prepare pure, solution, 67. 

hypophosphite, 344. 

iodate, 75, 295. 

iodide, 73, 628. 

manganate, 76, 229. 

mvronate, 445. 

nitrate, 61, 72, 286, 661. 

oleate, 451. 

perchlorate, 293. 

periodide, 271. 

permanganate, 76, 229, 619, 629. 

preparation of, 61. 

properties of, 61. 

quantitative estimation of, 617, 
619. 

quantivalence of, 62. 

red chromate, 103, 237. 

salts, analogy of, to sodium salts, 
87. 

sodium and ammonium, separa- 
tion of, 99, 100. 

sodium tartrate, S6. 

sources of, 61. 

sulphate, 72, 286. 

sulphides, 67. 

sulphite, 631. 

sulphocyanate. 356. 

sulphurated, 67. 

tartrate. 72. 

acid, 78, 318. 

tri-iodide, 271. 

yellow chromate, 103. 
prussiate, 278, 340. 
Potato, 463. 

starch (fig.), 465. 
Poultices, 574. 
Pound, 595. 

Powder, bleaching, 112. 
Powders, 574. 

soda, S7. 

specific gravity of, 602. 
Practical analysis, 99. 
Precipitant, 77. 
Precipitate, 77. 
Precipitated chalk, 107. 



757 



Precipitated sulphur, 302. 
Precipitates, soluble, in solutions of 
salts, 281. 

to wash, 107, 108, 640. 

to weigh, 639, 644. 
Precipitation, 77. 

Preparations of the Pharmacopoeia, 
chemical, 576. 

galenical, 574. 
Prepared carbonate of calcium, 109. 

chalk, 109. 

lard, 454. 

suet, 454. 
Pressure, correction of volume of gas 
for, 605. 

-gauges, 579. 
Prickly ash, 520. 
Primary alcohols, 432. 
Principles of Chemical Philosophy, 

36 (vide also Law*). 
Prinos, 359. 
Printer's ink, 541. 
Prismatic nitre, 284. 
Prollius's method for estimation of 

cinchona alkaloids, 675. 
Proof spirit, 436. 
Propane, 395. 

Propane-Mcarboxylic acid, 488. 
Propargyl alcohol, 409. 
Propenyl, 450. 

alcohol, 450. 

hydrate, 450. 
Propepsin,- 535. 
Propeptone, 536. 
Prophetin, 493. 
Propione, 488. 
Propionic acid, 479. 
Proportions, atomic, 47, 195. 

constant, 47, 58. 

multiple, 48, 58. 

reciprocal; 48, 58. 
Propyl-formic acid, 479. 
Propylic acid, 479. 

alcohol, 443. 
Propylmethylbenzene, 428. 
Protocatechuic aldehyde, 364. 
Protopine, 507. 
Proximate analysis, 669. 
Prune, 460. 
Prunum, 460. 
Primus serotina, 490. 

Virgiuianum, 490. 
Prussian blue, 340, 5-10. 
Prussiate of potash, red, 341. 

yellow, 278, 340. 
Prussic acid, 277. 
Pseudaconitine, 519. 
Pseudojervine, 525. 
Pseudomorphine, 507. 



Pseudoxanthine, 502. 
Pterocarpin, 539. 
Pterocarpus santalinus, 539. 
Ptomaines, 502, 556. 
Ptyalin, 570. 
Ptychotis ajowan, 412. 
Puce-colored peroxide of lead, 210. 
Puddling, iron, 140. 
Pulsatilla, 335. 
Pulvis Algarothi, 178. 

angelicus, 178. 

antimonialis, 181. 

effervescens compositus, 321. 

ipecacuanhse et opii, 524. 

morphinse compositus, 506. 
Pumice-stone, 354. 
Punica granatum, 359. 
Purified ox-bile, 536. 
Purple of Cassius, 244. 

foxglove, active principle in, 493. 
Purpurine, 563. 
Purrate of magnesium, 538. 
Purree, 538. 
Pus, in urine, 569. 
Putrescine, 502. 
Putty powder, 241. 
Pyrethrin, 421, 527. 
Pyrethrum, 421. 

cameum, 421. 

cineraria folium, 421. 

roseum, 421. 
Pyridine, 503. 
Pyrites, copper, 188. 

iron, 140. 
Pyroarseniate of sodium, 167. 
Pyroarseniates, 167. 
Pyrocatechin, 449. 
Pyrogallic acid, 360. 

use of, in gas-analysis, 360. 
Pyrogallol, 360. 
Pyroligneous acid, 296. 
Pyrolusite, 228. 
Pyromellitic acid, 488. 
Pyrometers, 583. 
Pyromorphite, 332. 
Pyrophorus, 156. 
Pyrophosphates, 332, 353. 
Pyrophosphoric acid, 350, 352. 
Pyrotartaric acid. 1ST. 
Pyro vanadates. :Y.\2. 
Pyroxylic spirit, 432. 
Pyroxylin, 470. 
Pyroxylinum, 170. 

QtJ ADM VALENCE, 56. 

Qualitative analysis. 99. 
Quantitative analysis. 576 el e«o. 
Quantivalenoe, 55, 121. 

of atoms, definition of, 58. 



758 



Quantivalence of acidulous radicals 

66. 
Quartz, 354. 
Qaassiee lignum, 496. 
Quassin, 496. 
Quebrachine, 519. 
Quebracho-bark, 519. 
Quercitrin, 538. 
Quercitron, 538. 
Quercus alba, 357. 

cortex, 358. 

tinctoria, 538. 
Quevenne's iron, 156. 
Quicklime, 105. 
Quillaia, 49S. 
Quillaic acid, 498. 
Quinamine, 515. 
Quinia (see Quinine), 510. 

analytical reactions of, 511. 

citrate, 511. 

of iron and, 152. 

disulphate, 511. 

iodo-sulphate, 512. 

kinate, 510. 

quantitative estimation of, 674. 

sulphate, 510. 
Quinicine, 515. 
Quinidinse sulphas, 513. 

impurities in. 704. 
Quinina, 510. 

impurities in, 704. 

bisulphas, 511. 

impurities in, 704. 

hydrobromas, 511. 

impurities in, 704. 

hydrochloras, 511. 

impurities in, 704. 

sulphas, 384, 510. 

impurities in, 704. 

valeriaaas, 511. 

impurities in, 704. 
Quinine. 510. 
Quiniretin, 515. 
Quinoidine, 514. 
Quinoline, 504. 
Quinquivalence, 56. 

Radicals, 67. 

acidulous, 60, 260. 
formulae of, 122. 

basylous, 60, 121. 

definition of, 60. 
Raceniic acid, 318. 
Rai, 445. 
Raisins, 460. 
Ranunculus, 335. 
Raspberry, sugar in, 45S. 
Ratafia, 436. 
Rational formula. 1 , 509. 



Ratti, 494. 

Reactions, analytical, 62. 

synthetical, 62. 
Reagents, list of, xiii. 
Real' alcohol, 437. 
Realgar, 164. 

Reaumur's thermometer, 580. 
Reciprocal proportions, law of, 50. 
Rectification, 127. 
Rectified oil of turpentine, 410. 

spirit, 127, 436. 
Reduced indigo, 289. 

iron, 155. 
Reinsch's test for arsenicum, 170. 
Relations of gases, liquids, and solids, 

42. 
Relative weight of hydrogen and oxy- 
gen, 24. 
Remijia-bark, 515. 
Rennet, 532. 
Reseda luteola, 538. 
Resin, 410, 419. 

arnica, 420. 

cannabis, 420. 

capsicum, 420. 

castor, 420. 

copaiba, 422. 

copal, 420. 

dragon's blood, 420. 

ergot, 420. 

guaiacum, 421, 494. 

Indian hemp, 420. 

jalap, 421, 495. 

kamala, 421. 

kousso, 421. 

mastic, 421. 

mezereon, 421. 

oils, 419. 

pepper, 421, 527. 

podophyllum, 421. 

pyrethrum, 421. 

rottlera, 421. 

scamicony, 498. 

soap. 453. 
Mesina, 419. 

copaiba, 422. 

jalapvp, 495. 

2)odoplnjlli, 421. 

scammonii, 497. 
Resins, 410, 419. 
Resorcin, 448. 

Respiratory materials of food, 534. 
Retort, 126. 
Rhaeadine, 507. 
Rkamni succus, 492, 540. 
Rhamnin, 538. 
Rhamnus catharticns, 540. 

frangula, 492. 
Rhapunticin, 337. 



759 



Rhatany-root, 359. 
Rheic acid, 337. 
Rhein, 337. 
Rheubarbic acid, 337. 
Rheubarbarin, 337. 
Rheum, 337. 
Rheumin, 337. 
Rhodium, 246, 713. 
Rhceados petala, 539. 
Rhubarb, oxalate of calcium from, 
567. 
acid, in, 348. 
Rhus coriaria, 359. 
cotinus, 538. 
glabra, 359. 
toxicodendron, 360. 
Rice, 464. 

Rice-starch (fig.), 465. 
Ricinine, 456. 

Ricinoleate of glyceryl, 456 
Ricinolein, 446. 
Ringworm-powder, 337. 
Roccella, 456. 
Rochelle salt, 86, 319. 
Rock-salt, 80. 
Roll sulphur, 300. 
Roman cement, 354. 
Rosse caninse fructus, 460. 
centifolise, 539. 
gallicse, 539. 
Roscoe's vanadium, 332. 
Roseaniline, 427, 541. 
Rosemary oil, 414. 
Rose oil, 414. 
-petals, 539. 
-water, 411, 414. 
Rosin, 410. 
Rosmarinus, 414. 
Rotten-stone, 136. 
Rottlera tinctoria, 421. 
Rottlerin, 421. 
Rouge, animal, 337, 540. 
mineral, 150, 540. 
vegetable, 540. 
Rubia tinctorum, 539. 
Rubidium, 713. 
Rubijervine, 525. 
Rabun. 323, 359. 
idssus, 458. 
Ruby, 136. 
Rue oil, 414. 
Rum, 436. 
Rumex, 338. 

crispus, 338. 
Rumicin, 337. 
Rust of iron, 140. 
Rutato of glyceryl, 454. 
Ruthenium, 246, 713. 
Rutic acid, 454. 



Rutic aldehyde, 415. 

Sabadillia or sabadilline, 529. 

Sabina, 416. 

Sabin&s, oleum, 416. 

Saccharated carbonate of iron, 143. 

volumetric estimation of, 634. 

pepsin, 536. 
Saccharic acid, 462. 
Saccharimetry, 682. 
Saccharin, 439. 

soluble, 440. 
Saccharine, 460. 

substances, 458, 460. 
Saccharometer, 683. 
Saccharomyces cerevisise, 435. 

impurities in, 704. 
Saccharons, 460. 
Saccharoses, 460. 
Saccharum, 460. 

impurities in, 704. 

lactis, 462. 

ustum, 462. 
Safety-lamp, 23. 

-tube, 264. 
Safflower, 539. 
Saffranin, 538. 
Saffron, 538. 

bastard, 539. 

dyer's, 539. 
Safrol, 416. 
Sage, 416. 
Sago, 464. 

starch (fig.), 465. 
Sal ammoniac, 89. 

prunella, 284. 

volatile, 92. 
Salep, 470. 
Salicinum, 496. 

impurities in, 704. 
Salicylate of lithium, 225. 

methyl, 404. 

phenyl, 483. 

sodium, 483. 
Salicylic acid, 404, 450, 483. 

aldehyde, 404. 
Salicylol, 404. 
Salicylous acid, 404. 
Saligenin, 496. 
Saligcnol, 450. 
Saliretin, 497. 
Saliva, 570. 
Salix alba, 496. 

helix, 496. 
Salol, is;;. 
Salseparin, 407. 
Salt, common, SO. 

definition of a, 01. 

of sorrel, 315. 



760 



Saltpetre, 284. 

Chili. 284. 
Salts, acid, 301. 

action of the blowpipe on, 373. 
of heat on, 372. 
of sulphuric acid on, 372. 

alky], 474. 

of ammonium, volatility of, 97. 

analogies of, 88. 

analysis of insoluble, 370. 

constitution of, 60, 125, 260, 284, 
29S, 379. 

formation of, 69. 

nomenclature of, 71, 75. 

of iron, nomenclature of, 141. 

physical properties of, 371. 

substitution of, for each other, 87. 

Table of the solubility or insolu- 
bility of, in water, 367. 
Salvia. 415. 
Salviol, 415. 
Sambucene, 416. 
Sambueus, 416. 
Sand, 354. 

-bath, 28. 

-tray, 28, 199. 
Sandal-wood, oil of, 416. 

red, 416. 

white, 416. 

yellow, 416. 
Sandstone, 354. 
Sanguinaria,. 527. 

vinegar, 297. 
Sanguinarina, 527. 
Santalin, 539. 
Santalum album, 416. 

rubrum, 416, 539.] 
Santonic acid, 497. 
Santonica, 497. 
Santonin, 497. 
Santoninate of sodium, 497. 
Santoninum, 497. 

impurities in, 704. 
Santoniretin, 497. 
Sapan-wood, 539. 
Sap-green, 540. 
Sapo, 453. 

animalis, 453. 

kalinus venalis, 453. 
impurities in, 704. 

mollis, 453. 

vi rid is, 453. 

impurities in, 704, 705. 
Saponification, 453. 
Saponin, 497. 
Sapotoxin, 514. 
Sapphire, 136. 
Saprine, 502. 
Sarcinse ventriculi in urine, 571. 



Sarcocephalus esculentus, 420. 
Sarcolactic acid, 348. 
Sarkine, 504. 
Sarkosine, 502. 
Sarracenia purpurea, 529. 
Sarsaparilla, 498. 
Sassafras, 416. 

medulla, 470. 

oil, 416. 

pith, 470. 
Sassafrol, 416. 
Saturated hydrocarbons, 391. 

solutions, boiling-points of, 582. 
Saturation, 69. 

tables, 320, 324, 710. 
Saturn, 208. 
Saturnine colic, 208. 
Savin oil, 416. 
Saxon blue, 540. 
Saxony blue, 540. 
Scale, compounds of iron, 151. 
Scammonii resina, 498. 

impurities in, 705. 
Scammonin, 498. 
Scammoniol, 498. 
Scammonium, 498. 

impurities in, 705. 
Scammony, resin of, 498. 
Scandium, 713. 
Scents, 412. 
Scheele's ^reen, 174. 
Schist, 136. 
Schonbein's test for hydrocyanic acid, 

282. 
Schweinfurth green, 174. 
Science of Chemistry, 14. 
Scilla, 461. 
Scillin, 498. 
Scillitin, 498. 
Sclerotic acid, 420. 
Sclerotinic acid, 420. 
Scoparin, 528. 
Scnparius, 528. 
Scopoleine, 520. 
Scopoletin, 520. 
Scoj)olia japonica, 520. 
Scutellaria, 516. 
Sea-salt, 80. 
Sebacate of ethyl, 404. 
Secondary alcohols, 432. 
Sediments, urinary. 564. 

microscopic examinations of, 
565. 
Seed-lac, 540. 
Seidlitz powder, 320. 
Selenic acid, 301. 
Selenion, 713. 
Selenious acid, 301. 
Selenium, 301, 713. 



761 



Senega, 498. 

Senna, 491. 

Sepia, 541. 

Serolin, 531. 

Serpentaria, 500. 

Serpent's excrement, 361. 

Sesame oil, 456. 

Sesamum indicum, 456. 

Sevum, 454. 

Sexivalence, 56. 

Shale, 136. 

Shark-liver oil, 456. 

Shell-fish poison, 502. 

Shell-lac, 540. 

Sherry wine, 436. 

Shumac, 359. 

Sienna, 541. 

Sifting, an aid to analysis, 371. 

Silica, 354. 

Silicate of aluminium, 137. 

calcium, 104, 354. 

magnesium, 354. 
Silicates, 354. 

quantitative estimation of, 667. 

tests for, 354. 
Silicic acid, 354. 

anhydride, 355. 
Siliciuretted hydrogen, 355. 
Silico-fluoride of barium, 103. 
Silicon chloride, 355. 

derivation of word, 33. 

fluoride, 355. 

hydride, 355. 

oxide, 355. 
Silver, 213. 

ammonio-nitrate, 175, 204. 

analytical reactions of, 216. 

antidotes to nitrates of, 217. 

arseniate, 175, 217. 

arsenite, 174. 

bromide, 217. 

by cupellation, estimation of, 657. 

chloride, 214. 

chromate, 217. 

citrate, 325. 

cyanide, 217, 281. 

derivation of word, 33. 

extraction of, 213. 

German, 233. 

iodide, 217. 

nitrate, 214, 215, 656. 
diluted, 215, 656. 
moulded, 215, 656. 

oxalate, 316. 

oxide, 216, 656. 

phosphate, 217. 

pure, 215. 

quantitative estimation of, 656, 
657. 



Silver, standard solution of nitrate of, 
624. 

sulphide, 217. 

sulphite, 306. 

tartrate, 321. 

tree, 217. 

volumetric estimation of, 656. 
Sinalbin, 445. 
Sinapis, 445. 
Sinigrin, 445. 
Sinistrin, 515. 
Siphon {vide Syphon). 
Size, 534. 
Skullcap, 500. 
Slaked lime, 106. 
Slate, 136. 
Smalt, 232, 540. 
Smilacin, 497. 
Smilax officinalis, 498. 
Snakeroot, black, 500. 

Virginia, 500. 
Soap, ammonium, calcium, Castile, 
green, hard, Marseilles, mot- 
tled, potassium, sodium, soft, 
453. 
Soap-bark, 498. 

curd, 453. 

-stone, 541. 

-wort, 497. 
Socaloin, 541. 
Socotrine aloes, 430. 
" Soda," 314, 618. 

-alum, 137. 

-ash, 87, 618. 

caustic, 81. 
Soda canstica, 81. 

impurities in, 705. 

tartarata, 86. 
Soda-lime, 672. 

-powders, 87. 

solution of chlorinated, 86, 637. 

standard solution of, 621. 

valerianate, 362. 

volumetric estimation of, 619. 

-water, S5. 
Sodse (vide Sodii). 

fulminate, 216. 
Sodii acetas, 82. 

impurities in, 705. 

arsenias, 167. 

impurities in, 705. 

benzoas, 336. 

impurities in, 705. 



5tci 



. 83. 



n. 70."). 



impurities 
venalis, 82, 
bisidpliis, 305. 

impurities in. 705. 
Volumetric estimation of. 631. 



762 



Sodii boras, 333. 

impurities in, 705. 
bromidum, 268, 627. 

impurities in, 705. 

volumetric estimation of, 627. 
carbonas, 83, 312. 

impurities in, 705, 706. 

exsiccatus, 83. 
cMoras, 87, 293. 

impurities in, 706. 
chlorata, liquor, 86, 637. 
chloridum, 80. 

impurities in, 706. 
citro-tartras effervescens, 86. 
hypophosphis, 314. 

impurities in, 706. 
hyposulphis, 345. 

impurities in, 706. 

volumetric estimation of, 631. 
liquor, SI. 
nitras, 284. 

impurities in, 706. 
phosphas, 111. 

impurities in, 706. 
pyrophosphas, 353. 

impurities in, 706. 
salicylas, 483. 

impurities in, 706. 
santoninas, 497. 

impurities in, 706. 
silicatis, liquor, 355. 
sulphas, 265. 

impurities in, 707. 
sutyhis, 305. 

impurities in, 7"07. 

volumetric estimation of, 
631. 
sulphocarbolas, 448. 

impurities in, 707. 
valerianas, 362. 
Sodic carbonate, etc. {vide Salts of 

Sodium). 
Sodio-citrate of iron, 153. 
-tartrate of iron, 153. 
Sodium, 80. 
acetate, 82. 
acid carbonate, 82, 617. 

sulphate, 265. 

tartrate, 79. 
analytical reactions of, S8. 
and aluminium, double chloride, 

136. 
arseniate, 167. 
arsenite, 166. 
benzoate, 336. 
benzoldisulphonate, 448. 
bicarbonate, 82. 

chemically pure, 618. 
bisulphite, 305, 631. 



Sodium bromate, S7. 

bromide, 267. 

carbonate, 86, 617. 

chemically pure, 618. 

dried, 84. 

manufacture of, 87, 311. 

carbonates, 617. 

volumetric analysis of, 617. 

chlorate, 87, 293. 

chloride, 80. 

cholate, 536. 

citrate, 87. 

derivation of word, 32. 

ethylate, 438. 

flame, 88. 

glycocholate, 536. 

hydrate, 81. 

hypochlorite, 86. 

hypophosphite, 344. 

hyposulphite, 345. 

iodate, 87. 

manganate, 87. 

molybdate, 331. 

nitrate, 81, 2S4. 

other compounds of, 87. 

oxalate, 315. 

permanganate, 87. 

phosphate, 111. 

how prepared from phos- 
phate of calcium, 111. 

potassium and ammonium, sepa- 
ration of, 99. 

pyroarseniate, 167. 

pyrophosphate, 353. 

quantitative estimation of, 617, 
643. 

salicylate, 483. 

salts, analogy of, to potassium 
salts, 87. 

sources of, 80. 

santoninate, 497. 

sulphate, 265. 

sulphite, 305, 631. 

sulphocarbolate, 44S. 

taurocholate, 536. 

valerianate, 362. 
Soft soap, 453. 
Soils, analysis of, 686. 
Solania, 527. 
Solanidine, 527. 
Solanine, 527. 
Solanum dulcamara, 527. 

tuberosum, 527. 

starch of (fig.), 465. 
Solazzi-juice, 494. 
Solder, 207, 239. 
Solid, definition of, 58. 

fats, 454. 

potash, 67. 



763 



Solids, lighter than water, to take the 
specific gravity of, 603. 
to take the specific gravity of, 601 
et seq. 
Solubility of carbonic acid gas in 
water, 85. 
of gases in liquids, 85. 
of precipitates in strong solutions 

of salts, 281. 
or insolubility of salts in water, 
Table of, 367. 
Soluble cream of tartar, 333. 
glass, 355. 
saccharin, 439. 
substances, to take the specific 

gravity of, 603. 
tartar, 73. 
Sonnenschein's process for poisonous 

alkaloids, 554. 
Soot, 30. 
Soubresauts, 279. 
Source of heat, 17. 
Sovereign, weight of the, 243. 
Soymida febrifuga, 500. 
Sozolic acid, 439. 
Spanish liquorice, 494. 
Spar, fluor-, 342. 
heavy, 102. 
Sparteia or sparteine, 528. 
Spathic iron ore, 140. 
Spearmint oil, 414. 
Specific gravity, 598. 
of gases, 604. 
of liquids, 599. 
of official liquids, 600. 
of oxygen, 24. 
of powders, 602. 
of solids, 601. 

lighter than water, 603. 
of soluble substances, 603. 
Specific heat, 128. 

weight, 598. 
Spectroscope, 545. 
Spectrum analysis, 545. 
Specular iron ore, 139. 
Speculum metal, 239. 
Speiss, 233. 
Spermaceti, 444, 583. 
Spermatozoa in urine, 571. 
Sperm oil, 444. 
Spigclia, 528. 

Spi'rcea ulmaria, 404, 484, 496. 
Spirit of French wine, 438. 
methylated, 432. 
mindererus, 91. 
myrcia, 436. 

of nitrous ether, 351, 400. 
adulterated, 433. 
of turpentine, 410. 



Spirit of wine, 436. 

petroleum, 496. 

proof, 436. 

pyroxylic, 432. 

rectified, 436. 

wood-, 433. 
Spirits, 574. 

analysis of, 684. 
Spodumene, 223. 
Spogel-seeds, 470. 
Sponge, 533. 
Spongy platinum, 245. 
Spontaneous combustion, 155. 
Spotted cranesbill, 356. 
Spruce fir, 421. 
Spurge laurel, 421. 
Squalus carcharis, 456. 
Squill, 461, 470, 498. 
Stannate of sodium, 241. 
Stannates, 240. 
Stannic acid, 240. 

anhydride, 240. 

chloride, 240. 

oxide, 240. 

sulphide, 241. 

anhydrous, 242. 
Stannous chloride, solid, 240. 

hydrate, 241. 

oxide, 241. 

sulphide, 241. 
Stannum, 34. 
Staphisagria, 524. 
Star-anise oil, 412. 
Starch, 463. 

blue, 463. 

cellulose, 464. 

gelatinized, 464. 

iodized, 464. 

quantitative estimation of, 682. 

soluble, 468. 

-sugar, 459, 468. 
Starches, microscopy of, 466. 
Stas's process for poisonous alkaloids, 

553. 
Stavesacre, 524. 
Steam-bath, 641. 
Stearic acid, 452, 479, 4S1. 
Stearine, 452. 
Steatite, 541. 
Steel, 140. 

wine, 153. 
Stick-lac, 540. 
Stibium, 32. 
Still, 126. 

Stillingia sylvatica, 52S. 
Stillingine, 52S. 
Stone-coal. 239. 

red. 539. 
Storax, 119. 



764 



Stout, 436. 

Strain onii folia et semen, 525. 
Strasburg turpentine, 409. 
Strawberry, 323, 348, 458. 
Stream tin, 239. 
Strophanthidin, 498. 
Strophanthin, 498. 
Strontianite, 226. 
Strontium, 226. 

analytical reactions of, 226. 
carbonate, 226. 
derivation of word, 33. 
flame, 227. 
nitrate, 226. 
sulphate, 226. 
Structure of flame, 23. 
Strychnia or strychnine, 515. 
citrate, 516. 
impurities in, 707. 
analytical reactions of, 516, 550. 
in organic mixtures, detection of, 

550. 
sulphate, 516. 
Strychnin, 515. 

impurities in, 707. 
Strychninse sulphas, 516. 
Strychnos Ignatia, 515. 

nux vomica, 515. 
Styracin, 485. 
Styrax, 485. 

pr&paratus, 485. 
Styrol, 485. 
Styrone, 485. 
Subacetate of copper, 190. 

of lead, 209. 
Subchloride of mercury, 200. 
Suberate of ethyl, 404. 
Sublimation, 92, 202. 
Sublimed sulphur, 300. 
Subnitrate of bismuth, 249. 
Substances readily deoxidized, quan- 
titative estimation of, 636. 
oxidized, quantitative estimation 
of, 629. 
Substitution-products, 398. 
Succinate of potassium, 356. 
Succinic acid, 355. 
Succinum, 355. 
Succus limonis, 324. 
Sucrose, 460. 
Suet, 454. 
Sugar, 458. 

amount in various fruits, 458. 

brown, 460. 

candy, 460. 

cane-, 460. 

detection of, in urine, 558. 

from caoutchouc, 460. 

from fish, 460. 



Sugar from gum arabic, 460. 
from meletizose, 462. 
from melitose, 460. 
from mountain-ash, 460. 
from muscles, 460. 
from maltose, 462. 
from lard, 462. 
from eucalyptus, 462. 
from Turkish manna, 462. 
grape-, 458. 
inverted, 458. 
loaf-, 460. 
maple-, 460. 
milk-, 462. 
moist, 460. 
of gelatin, 536. 

lead, 209. 
quantitative estimation of. 681. 
test for, 459, 461. 
Suint, 452. 

Sulphamidobenzoates, 440. 
Sulphate of aluminium, 137. 

and potassium, 136. 
ammonium, 90. 

and iron, 136. 
barium, 102. 
bismuth, 250. 
cadmium, 247. 
calcium, 104, 113. 
chromium, 236. 
cinchonine, 514. 
cobalt, 232. 
copper, 18.9. 

anhydrous, 190. 
indigo, 289. 
iron, 141, 635. 

precipitated, 142. 

solution of, 148. 
lead, 212. 

magnesium, 116, 647. 
manganese, 231. 
mercury, 197. 
potassium, 72, 286. 
quinine, 511. 
sodium, 86, 265. 
strontium, 226. 
zinc, 130. 
Sulphates, 307. 

analytical reactions of, 309. 
quantitative estimation of, 662. 
Sulphethylic acid, 441. 
Sulphide of ally], 445. 
ammonium, 95. 
antimony, 177, 182. 
arsenicum, 164, 173. 

native, 164. 
barium, 102. 
bismuth, 251. 
cadmium, 247. 



765 



Sulphide of calcium, 302. 

cobalt, 232. 

copper, 189. 

iron, 144. 

lead, 211. 

native, 207. 

manganese, 230. 

mercury, 205. 
native, 192. 

nickel, 234. 

potassium, 67. 

silver, 217. 

native, 215. 

tin, 241. 

zinc, 134. 
Sulphides, 300. 

analytical reactions of, 303. 

native, 164. 

quantitative estimation of, 661. 
Sulphindigotic acid, 289. 
Sulphindylic acid, 289. 
Sulphite of barium, 306. 

calcium, 305. 

magnesium, 305. 

potassium, 305, 631. 

silver, 306. 

sodium, 305. 
Sulphites, 304. 

analytical reactions of, 305. 

quantitative estimation of, 631, 
644. 
Sulphocarbolates, 448. 
Sulphocarbolic acid, 448. 
Sulphocarbonates, 313. 
Sulphocarbonic anhydride, 313. 
Sulphocyanate of acrinyl, 445. 

allyl, 445. 

butyl, 412. 

iron, 356. 
Sulphocyanates, 356. 
Sulphocyanic acid, 356. 
Sulphocyanides, 357. 
Sulphocyanogen, 357. 
Sulphonal, 440. 
Sulphonic acids, 439. 

alcohols, 439. 

ethers, 439. 
Sulphophenates, 448. 
Sulphophenic acid, 448. 
Sulphosalicylic acid, 483. 
Sulphostannatcs, 242. 
Sulphovinic acid, 441. 
Sulphur, 30. 

adultoration of, 303. 

allotropy of, 298. 

analytical reactions of, 303. 

arsenic in, 172. 

bromide. 304. 

chloride, 304. 



Sulphur, derivation of word, 31. 
estimation of, 644. 
flowers of, 298. 
hypochloride, 304. 
iodide, 271, 303. 
liver of. 67. 
milk of, 302. 
oxyacids, 343. 
plastic, 298. 
precipitated, 302. 
roll, 300. 
sublimed, 300. 
Sulphur lotum, 300. 

impurities in, 707. 
prxcipitatum, 302. 

impurities in, 707. 
sublimatum, 300. 

impurities in, 708. 
Sulphurated antimony, 180. 
lime, 113. 
potassa, 67. 
Sulphurets (vide Sulphides), 
Sulphuretted hydrogen, 300. 
Sulphuric acid, 306. 

antidotes to, 310. 
aromatic, 309. 
dilute, 309. 
fuming, 309. 
Nordhausen, 309. 
in organic mixtures, detec- 
tion of, 549. 
purification of, 309. 
standard solution of, 620. 
volumetric estimation of, 623. 
anhydride, 309. 
Sulphuris iodidum, 272. 

impurities in, 707. 
Sulphurous acid, 304. 

volumetric estimation of, 629. 
anhydride, 304. 
Sulphydrate of ammonium, solution 

of, 95. 
Sulphydric acid, 300. 
Sumach, 359. 
Sumatra camphor, 418. 
Sumbul, 423. 

Superphosphate of lime, 327. 
Supporters of combustion, 22. 
Suppositories, 574. 
Surface, unit, 58S. 
Surgery, 14. 
Swoetbread, 536. 
Sweet spirit of nitre, 351, 400. 

adulterated, 433. 
Sylvic acid, 419. 
Symbol, function of, 41, 52. 
Symbols of elements, 31, 41. 

illustration of ehomu-al action 
by, 47. 



766 



Sympathetic inks, 233. 
Synaptase, 490. 
Synthesis, 60. 
Syphon, 108. 
Syrup, 460. 

of iodide of iron, 30, 145. 
Syrups, 574. 

specific gravities of, 601. 
Syrupi, impurities in, 708. 
Syrupus, 460. 

acidi hydriodici, 272. 

impurities in, 708. 
aurantii, 413. 

flurum, 413. 
calcii lactopho8pliati8, 111. 
calcis, 106. 
ferri bromidi, 145. 

impurities in, 708. 
iodidum, 30, 145. 

impurities in, 708. 
phosphatis, 144. 
quininse et strychninse phos- 

phatum, 517. 
hypophosphitum, 344. 
cumferro, 344. 

Tabacum, 526. 

Tables, various {vide Appendix). 

Tamarindus, 323. 

impurities in, 708. 
Tanacetic acid, 497. 
Tanacetum, 497. 
Tannic acid, 357. 
Tanning, 357. 
Tansy, 497. 
Tantalum, 713. 
Tapioca, 464. 

starch (fig.), 465. 
Taraxaci radix, 500. 
Taraxacin, 500. 
Tartar, meaning of, 318. 

cream of, 73, 79, 318. 

emetic, 179, 318. 

estimation of antimony in, 
651. 
Tartarated antimony, 179. 
Tartaric acid, 317, 318. 

saturating power of, 318. 

series of acids, 486. 

solution of, 321. 
Tartarus boraxatus, 333. 
Tartrate of ammonium, 98. 

antimony and potassium, 179, 
318. 

calcium, 321. 

potassium, acid, 72, 79. 
neutral, 72, 318. 
and sodium, 86, 319. 

silver, 321. 



Tartrate of sodium, 79. 
Tartrates, 73, 317. 

analytical reactions of, 321. 

volumetric estimations of, 618. 
Tartronic acid, 487. 
Taurine, 502, 536. 
Taurocholates, 536. 
Teal oil, 456. 
Telini fly, 418. 
Tellurium,. 301, 713. 
Temperature, correction of volume of 
gas for, 604. 

measurement of, 579. 
Terebene, 410. 
Terebenthene, 409. 
Terebinthina canadensis, 409, 423. 
Terpene series of hydrocarbons, 409. 
Terpenes, 409. 
Terra di sienna, 539. 

japonica, 358. 
Tertiary alcohols, 432. 

amylic alcohol, 443. 
Testa prseparata, 109. 
Test-papers, 94. 

-tube, 16. 
Tetanine, 502. 
Tetrabasic acids, 488. 
Tetrahydric alcobol, 456. 
Tetrane, 395. 
Tetrathionic acid, 346. 
Tetryl sulphocyanate, 413. 
Tetrylic acid, 479. 
Thalleiochin, 511. 
Thalline, 514. 
Thallium, 713. 
Thebaine, 507. 
Theia, 528. 
Theine, 528. 
Thenard's blue, 540. 
Theobroma cacao, 454. 

oil, 454. 
Therapeutics, definition and deriva- 
tion of, 14. 
Theriaca, 462. 
Thermolysis, 607. 
Thermometer, 580. 

Celsius's, 580. 

Centigrade, 580. 

Fahrenheit's, 5S0. 

Reaumur's, 580. 
Thermometric scales, conversion of 

degrees of, 581. 
Thionic acids, 346. 
Thiosulphates, 345. 
Thorinum, 713. 
Thorium, 713. 
Thorn-apple, 525. 
Thoroughwort, 500. 
Thuja occidentali8, 416. 



INDEX. 



767 



Thus americanum, 423. 
Thyme, oil of, 416. 
Thyruene, 416. 
Thymol, 416. 

impurities in, 708. 
Thymus vulgaris, 414, 416, 417. 
Tiglic acid, 456. 
Tin, 238. 

amalgam, 238. 

analytical reactions of, 239. 

antidotes to, 241. 

block, 239. 

chloride of, 239. 

derivation of word, 34. 

dropped or grain, 239. 

foil, 239. 

granulated, 239. 

oxide, 240. 

perchloride, 240. 

plate, 239. 

prepare-liquor, 241. 

stone, 239. 

tacks, 239. 

-white cobalt, 232. 
Tincal, 333. 

Tinctura ferri acelatis, 148. 
impurities in, 708. 

chloridi, 147. 

impurities in, 70S. 

iodi, 272, 638. 
Tincturse, 147. 
Tinctures, 147, 574. 
Titanium, 713. 
Tobacco, 526. 
Tvddalise radix, 500. 
Tolene, 485. 

Tolu, balsam of, 419, 427, 485. 
Toluene, 425. 

dihydric alcohols, 449. 

-sulphonic acid, 439. 
amide, 440. 
chloride, 440. 
Toluol, 427. 
Tolyl alcohol, 449. 

derivative?, 428. 
Toxicodendric acid, 360. 
Toxicology, 545. 
Tragacanth, 114, 
Tragacantha, 114. 
Treacle, 462. 
Triads, 122. 
Triangle wire, 98. 
Tribasic acids, 262. 
Tribasylous radicals, 262. 
Tribromophenol, 417. 
Tricarballvlic acid, 488. 
Trichloracetal, 47C>. 
Trichloraldehyde, 476. 
Trichlorbutylidene glycol, 479. 



Trichlorethylidene glycol, 477. 
Trichloromethane, 398. 
Trichloromethylbenzene, 428. 
Triethylamine, 501. 
Triethylia, 501. 
Trihydric alcohols, 456. 
Trihydroxy benzene, 456. 
Trihydroxyl derivatives of the hy- 
drocarbons, 449. 
Trimethylamine, 502. 
Trimethylmethane, 395. 
Trimethylphenb'ene, 425. 
Trinitrocellulin, 471. 
Triphane, 225. 
Tripoli, 354. 
Trithionic acid, 346. 
Triticum repens, 500. 

starch of (fig.), 465. 
Trituratio elaterini, 493. 
Tritylia, 502. 
Trivalence, 56. 
Trivalent radicals, 56, 122. 
Troches, 574. 

Trochisci sodii santoninatis, 497. 
Tropate of tropine, 520. 
Tropic acid, 520. 
Tropine, 520. 
Tube-funnels, 96. 
Tubes for collecting gases, 18. 

glass {vide Glass Tubes). 
Tungsten, 713. 
Tunicin, 471. 
Turgite, 50. 
Turkey corn, 523. 
Turmeric, 416. 

oil, 416. 

-paper, 95, 334. 
Tunnerol, 416. 
Turnbull's blue, 342, 540 
Turpentine, 409, 423. 

American, 409. 

Bordeaux, 410. 

Canadian, 409. 

Chian, 409. 

French, 409. 

rectified oil of, 410. 

spirit of, 4 10. 

Strasburg. 409. 

Venice, 409. 
Turpeth mineral, 198. 
Turps, 410. 

Tylophora asthmatica, 524. 
Type-metal, 177, 208. 
Types, chemical, .'IT'.'. 
Typical formulae, 379. 
Tyrotoxioon, 502, 556. 

I Ul.Ml FULV.fi, 470. 
I Ulmw, 470. 



768 



Ultimate analysis, 669. 
Ultramarine blue, 5-40. 

green, 540. 
Ultraquinine, 515. 
Urubelliferoue, 424. 
Umber, 541. 

burnt, 541. 
Uncaria gambler, 358. 
Unguentum ceruasse, 208. 

hydrargyria 193. 

avimoniati, 204. 
iodidi rtibri, 196. 
nitratis, 197. 
subchloridi, 200. 

iodi, 272. 

plumbi carbonatis, 208. 

veratriiise, 529. 
Units of capacity, 5S8. 

surface, 588. 

vreigbt, 588. 
Univalence, 56. 
Univalent radicals, 56, 122. 
Unsaturated hydrocarbons, 391. 
Uranium, 713. 
Urari, 517. 

Urate of litbium, 225. 
Urates, 361. 
Urceola elastica, 417. 
Urea, 338, 480. 

artificial, 338, 562. 
Urethane, 480. 
Uric acid, 361, 565. 
Urinary calculi, 571. 

examination of, 571. 

deposits or sediments, plates of 
(vide 566 et seq.). 

sediments, 564. 

microscopic examination of, 
565. 
Urine, 557. 

diabetic, 558, 683. 

estimation of urea in, 560. 

morbid examination of, 557. 
Urinometer, 601. 
Ustilago maydis, 420. 
Uvss, 460. 
Uva ursi, 359. 

Valerexe, 416. 

Valerian oil, 416. 

Valeriana, 416. 

Valerianate of ammonium, 363. 

amy], 404. 

iron, 363. 

quinia, 511. 

sodium, 362. 

zinc, 134, 363. 
Valerianates. 362. 
Valerianic acid, 362, 416, 443, 479. 



Valerol, 416. 
Valerone, 488. 
Vanadates, 332. 
Vanadinite, 332. 
Vanadium, 332, 713. 

relationship to nitrogen, phos- 
phorus, and arsenicum, 332. 
Vanilla, 363. 
Vanillic acid, 363. 
Vanillin, 363. 
Vapor acidi hydrocyanici, 2S0. 

chlori, 29. 

conite, 523. 

iodi, 271. 
Vapor-density, 605. 
Variolaria, 540. 
Vegetable albumen, 533. 

alkaloids, 502. 

and animal life, relation of, 19. 

casein, 533. 

crocus, 538. 

fibrin, 533. 

gelatin, 470. 

-green. 540. 

jelly, 470. 

rouge, 540. 
Venetian red, 151. 
Venice turpentine, 409. 
Veratralbine, 525. 
Veratri viridi radix, 525. 
Veratria or veratrine, 529. 
Veratrina, 529. 

impurities in, 708. 
Veratrum album, 525. 

viride, 525. 
Verdigris, 190. 
Vermilion, 205. 
Veronica virginica, 500. 
Viburnin, 500. 
Viburnum, 500. 
Vinegar, 297. 

estimation of mineral acids in, 
663. 
• impurities in, 708. 

of cantharides, 297. 
squill, 297. 
Vinum album, 436, 6S5. 

impurities in, 708. 

alburn fortius, 436. 

impurities in, 708. 

antimonii, 179. 

ferri amarum, 153. 
citratis, 153. 

rubrum, 436, 632. 

impurities in, 708. 

xericum, 436. 
Virginia snakeroot, 500. 
Vitellus, 530. 
Vitriol, blue, 142. 



769 



Vitriol, green, 142. 

oil of, 309. 

white, 142. 
Volatile oils (vide Oils). 
Volatility of salts of ammonium, 98. 
Volatilization, 98. 
Volcanic ammonia, 90. 
Volume, combination by, 52. 

of gas, corrections of, 605. 

molecular, 55. 
Volumetric analysis, 611. 

of antimony, 630. 
Vulcanite, 417. 
Vulcanized India-rubber, 417. 

Wahoo-bark, 500. 

Warmth of animals, how kept up, 19. 

Washing-bottles, 107, 640. 

precipitates, 107, 641. 
Water, 127. 

aerated, 85. 

ammonia in potable, 615. 

aspirator, 308. 

-bath, 641. 

boiling-point of, 582. 

chalybeate, 140. 

Cologne, 412. 

composition of, 22. 

crystallization, 84. 

quantitative estimation of, 
668. 

cubic inches of, in a gallon, 605. 

distilled, 127. 

evaporation of, 69. 

formation of, expressed by sym- 
bols, 43. 

hardness of, 314. 

hemlock, 414. 

lime-, 105. 

nitrites in, 350. 

of crystallization, 84. 

-oven, 641. 

oxygenated, 102. 

purification of, 125, 314. 

type, 379. 

weight of 1 cubic inch of, 605. 
of minim, drachm, ounce, 
pint, and gallon, 595. 
Wax, 444. 

paraffin, 396. 
Weighing- tubes, 640. 
Weight, 5S5. 

estimation of, 585. 

molecular, 55. 

of air, 605. 

hydrogen, 607 
water, 598. 

specific, 598. 
Weights, atomic, 51. 



Weights and measures of the British 
Pharmacopoeia of 1867, 595. 
of the metric decimal system, 

590 et seq. 
U. S. Pharmacopoeia of 1870, 
586. 

balance, 585. 

of litres at different temperatures, 
589. 

relation of metrical, to the weights 
of the U. S. Pharmacopoeia, 592. 

relative, 53. 
Weld, 538. 
Welding, 246. 
Wheaten flour, 463. 
Wheat-starch (fig.), 465. 
Whey, 462, 531. 
Whiskey, 436. 
White arsenic, 164. 

indigo, 288. 

lead, 208, 541. 

oak, 357. 

pepper, 527. 

pigments, 541. 

precipitate, fusible, 204. 
infusible, 204. 

rosin, 419. 

vitriol, 142. 

wax, 583. 
Whiting, 109, 541. 
Whortleberry, sugar in, 458. 
Wild black cherry, 490. 

marjoram, 414. 
Willow-bark, 347. 
Wine, 436, 684. 

antimonial, 179. 

iron, 153. 

orange, 436. 

sherry, 436. 

steel, 153. 

white, 436. 
Winterberry, 359. 
Wintergreen, oil of, 404. 
Wire-gauze tray, 28. 

triangle, 98. 
Witch-hazel, 500. 
Witherite, 102. 
Wood-charcoal, 111. 

creasote, 447. 

naphtha, 432. 

oil, 422. 

specific gravity of, 604. 

spirit, 432. 

tar, 410. 423. 
Woody nightshade, 527. 
Woorara, .">! 7. 
Wormsced, American, 117. 

Levant. 497. 

Wormwood, ill. 



770 



INDEX. 



Wourali, 517. 
Wrought iron, 140. 

Xanthine, 529, 573. 
Xanthocreatinine, 502. 
Xanthorrhiza apitfolia, 520. 
Xanthoxylum, 520. 

fraxineum, 520. 
Xylene, 425. 
Xyloidin, 464. 

Yard, 595. 
Yeast, 435. 
Yellow chromate of potassium, 235. 

coloring-matters, 538. 

dock, 337. 

ochre, 538. 

oxide of mercury, 201. 

parilla, 520. 

prussiate of potassium, 278. 

-root, 520. 

sienna, 538. 

wax, 444, 583. 

wood, 538. 
Yolk or yelk of egg, 530. 
Ytterbium, 713. 
Yttrium, 713. 

Zaffre, 232. 

Zanaloin, 430. 

Zanzibar aloes, 430. 

Zea mays, starch of (fig.), 465. 

smut, 420. 
Zinc, 129. 

acetate, 133. 

analytical reactions of, 134. 

antidotes to, 135. 

bromide, 132. 

carbonate, 129, 132. 

chloride, 130. 

derivation of word, 32. 



Zinc, detection of, in presence of alu- 
minium and iron, 159, 160. 
-ethyl, 395. 
ferrocyanide, 135. 
granulated, 20. 
hydrate, 135. 
in organic mixtures, detection of, 

547. 
iodide, 132. 
oxide, 133. 

quantitative estimation of, 647. 
sulphate, 130. 
sulphide, 134. 

native, 129. 
valerianate, 134, 363. 
white, 132. 
Zinci acetas, 133. 

impurities in, 708. 
bromiditm, 132. 

impurities in, 708, 709. 
carbonas prsecij)itatus, 132. 

impurities in, 709. 
chloridi, liquor, 131. 
chloridum, 131. 

impurities in, 709. 
iodidum, 132. 

impurities in, 709. 
oxidum, 133. 

impurities in, 709. 
phosphidum, 328. 

impurities in, 709. 
sidp>h.as, 130. 

impurities in, 709. 
valerianas, 134, 363. 
impurities in, 709. 
Zincum, 129. 

impurities in, 709. 
granulatum, 20. 
Zingiber, 417. 
Zirconium, 713. 
Zymotic alkaloids. 502. 



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